## 1. Outline of scientific debates over nativism



In human and animal psychology since Darwin there have been a number
of periods when the innate/acquired distinction was the subject of
heated scientific controversy. This section reviews some of these
debates. It provides a sense of how different scientists have
conceptualized instinct or innateness, the kinds of evidence
marshalled to support nativist hypotheses, and some of the recurring
objections that nativist proposals have encountered. In scientific
psychology the words "innate" and
"instinctive" have been used to refer to the same cluster
of properties, "instinct" being a now somewhat antiquated
term for an innate psychological trait. Hence, in this section we take
older debates over instinct to be about the same set of issues as more
recent debates over innateness.


### 1.1 Darwin versus Wallace



Charles Darwin pioneered an approach to the study of instinct that
aimed to show, above all, that instincts evolve gradually as
adaptations to a species' environment. Darwin's theory of
instinct was developed in opposition to William Paley, William Kirby,
and other influential Natural Theologians (Grinnell 1985; Richards
1981; 1987; Rochowiak 1988). Paley defined an instinct as "a
[behavioral] propensity prior to experience and independent of
instruction" (Richards 1981). Examples such as bird migration,
nest building, and mating preference seemed, to Paley, not possibly
acquired by experience. The best explanation for these instincts was
that they are Divinely implanted. Likewise, Kirby viewed animal
instincts as a means by which God animates the material world:
"if animals lost their instincts, birds would no longer build
their nests, or migrate, or learn to fly. Bears would not know when to
hibernate, nor salmon when to be driven upstream to spawn; the entire
animal kingdom would be thrown into disarray" (Grinnell 1985,
57). Like many theologically inspired naturalists at the time, Paley
and Kirby drew a sharp distinction between instinctive vs acquired
behavior. Since instincts were thought to be designed by God, and thus
perfect, there would be no need to supplement or modify them through
individual learning.



Darwin offered a naturalistic alternative to the theological account.
Marshalling anecdotes from zookeepers, breeders, and his own
observations, Darwin presented evidence that instincts adapt to a
changing environment. One process by which they evolve is unguided
variation and natural selection. However, like many of his
contemporaries, Darwin also accepted an alternative "inherited
habits" model of instinct evolution. Habits are behaviors that
originate as intelligent acts and become increasingly automatic over
repeated performances. Although historians disagree about which
mechanism Darwin took to be the more significant, it appears that he
took both natural selection and inherited habits to be involved in the
evolution of instinct. As he explained in *The Origin*,
"If we suppose any habitual action to become inherited -
and I think that this does sometimes happen - then the
resemblance between what originally was a habit and an instinct
becomes so close as not to be distinguished" (1859, 187).
Darwin's dual-mechanism view inspired other researchers to
explore the relationship between intelligence, habit, and instinct. Of
particular note is George Romanes, a protege of Darwin who sought to
clarify and elaborate his mentor's theory of instinct. In his
books on animal intelligence, Romanes (1882; 1883) distinguished two
types of instinct: *primary instincts* that evolve by a process
of natural selection, and *secondary instincts* that evolve by
the inheritance of acquired habits.



A noteworthy critic of Darwin's account of instinct was none
other than Alfred Russel Wallace, co-founder of the principle of
natural selection. Wallace was notoriously hostile to Darwin's
view of the human mind as the product of selection (Gould 1980). As he
asserted in a letter to Charles Lyell,



> 
> Unless Darwin can show me how this rudimentary or latent musical
> ability in the lowest races can have been developed by survival of the
> fittest - can have been of use to the individual or race so as
> to cause those who possessed it in a fractional greater degree than
> others to win the *struggle for life*, I must believe that some
> other power caused that development - and so on with every other
> especially human characteristic. (1869, quoted in (Richards 1987, 183)
> italics in original)
> 



Wallace was critical of Darwin's claim, defended extensively in
*The Descent of Man* (1871) that many human behaviors are
grounded in instincts that are shared with other species. In his
essay, "On instinct in man and animals," (1891) Wallace
presented alternative explanations for how allegedly instinctive human
behaviors might be acquired by learning (Gross 2010). In a paper
entitled "The philosophy of birds' nests", Wallace
argued that Darwin was wrong even about the instinctive basis of
animal behavior:



> 
> If instinct means anything, it means the capacity to perform some
> complex act without teaching or experience. It implies not only innate
> ideas but innate knowledge of a very definite kind... but in the
> particular instance of birds' nests which is usually considered
> its stronghold, I cannot find a particle of evidence of anything
> beyond those lower reason and imitative powers which animals are
> universally permitted to possess. (1891, quoted in Gross 2010, 503)
> 



Notice that Wallace understood instincts to involve knowledge
"of a very definite kind" that arises without teaching or
experience. By contrast, he allowed that animals inherit certain
general (i.e. non-specific) cognitive capacities, such as "lower
reason" and learning by imitation, but these were not classified
as instincts. Instead, Wallace described such general capacities as
emanating from the "organization of the nervous system"
(Gross 2010). He thought that these mechanisms provide a more
plausible explanation for the acquisition of most animal and human
behavior than Darwin's appeal to instinct.


### 1.2 The rise of instinct psychology at the turn of the 20th century



Wallace's criticisms were overshadowed by Darwin's
popularity and influence. The final decade of the 19th
century saw growing scientific interest in the study of instincts,
much of it in a Darwinian vein. This was also a period of intense
dispute about the nature of instincts. A key point of disagreement
concerned the relationship between instinct and habit during
development. William James outlined a list of roughly forty human
instincts in his *Principles of Psychology*, and famously
proclaimed that humans possess more (not fewer) instincts compared to
other animals. His list included such eyebrow-raising candidates as
"a native impulse in everyone to conceal love affairs", a
"genuine instinct of cleanliness", and an "instinct
of personal isolation, which in women is called coyness" (1890,
393). It is important to understand what James meant when classifying
such behaviors as instinctive. For James, the influence of instinct on
behavior takes place during early stages of development. As he
explained in *Principles of Psychology*, "Most instincts
are implanted for the sake of giving rise to habits and... this
purpose, once accomplished, the instincts themselves, as such, have no
raison d'etre in the psychical economy, and consequently
fade away" (1890, 398). Thus, to call a behavior
"instinctive" meant, for James, that it has a
developmental origin in some more basic behavior which itself required
no prior experience. After first performance, however, the original
behavior is modified by reason, learning, and habit. This
developmental model stood in contrast to the more static view of
instinct defended by Romanes and others, wherein instincts often
remain unmodified by experience into maturity.



A second point of scientific disagreement concerned the evolutionary
origin of instincts. The prevailing view, held by Romanes and others,
involved the inheritance of acquired habits.
"Late-19th century psychologists and intellectuals in
general assumed that heredity and environment could not be separated
functionally or treated as independent factors, because change induced
by the environment would sooner or later (depending on the author)
become a part of the organism's racial heritage" (Cravens
and Burnham 1971, 637-38). This model was fiercely criticized by
August Weismann (1891 (1888)), who drew a sharp distinction between
germ plasm and soma. On Weismann's model, the germ plasm (i.e.
hereditary material) is sequestered early in development placing it
beyond the influence of somatic modifications, including habits or
other traits acquired over the life of an organism. In addition,
Weismann maintained that selection acts only on traits that emanate
directly from the germline (Johnston 1987). He allowed that some
traits are the product of environmental modifications during
development. But these, Weismann held, could never become adaptations.
Thus, Weismann distinguished hereditary traits, which were under
direct control of the germline and could become adapted to the
environment, from acquired traits, which were due to arbitrary
environmental influences on the soma.



It is noteworthy that Weismann's views became popular at a time
when many behavioral scientists rejected the distinction between
innate vs acquired characteristics. Not only James, but also Conwy
Lloyd Morgan (1896), Henry Fairfield Osborn (Kemp 1896) and James Mark
Baldwin (1896) were developing models of behavioral evolution and
development that emphasized an interaction between learned and
hereditary factors (Boakes 1984). These authors followed Weismann in
accepting that habits did not become incorporated into heredity as
instincts, but sought to explain how it could *appear* that
acquired behavior became hereditary through mechanisms later, and
dismissively, labelled 'Baldwin effects'. According to
historian Timothy Johnston, Weismann's popularity explains,
"why the dichotomy [between innate vs acquired traits] has been
so influential and so long-lived in the twentieth century, despite
repeated and quite cogent arguments against it" (1995, 115).



We have just considered two points of disagreement over the nature of
instinct that arose in the late 19th century as this concept was
gaining in scientific currency. In fact, Morgan (1895) identified a
total of seven "definitional" issues surrounding the
instinct concept in his day. It is noteworthy, given how fecund the
concept of instinct was in motivating scientific research between
1880-1900, that instinct was already being criticised for its
ambiguity. Morgan expressed his frustration with this situation in the
following, frequently cited passage:



> 
> Instinctive activities are unconscious (Claus), non-mental
> (Calderwood), incipiently conscious (Spencer), distinguished by the
> presence of consciousness (Romanes), accompanied by emotions in the
> mind (Wundt), involve connate ideas and inherited knowledge
> (Spalding); synonymous with impulsive activities (James), to be
> distinguished from those involving impulse proper (Hoffding,
> Marshall); not yet voluntary (Spencer), no longer voluntary (Lewes),
> never involuntary (Wundt); due to natural selection only (Weismann),
> to lapsed intelligence (Lewes, Schneider, Wundt), to both (Darwin,
> Romanes); to be distinguished from individually-acquired habits
> (Darwin, Romanes, Sully, and others), inclusive thereof (Wundt); at a
> minimum in man (Darwin, Romanes), at a maximum in man (James);
> essentially congenital (Romanes), inclusive of individually-acquired
> modifications through intelligence (Darwin, Romanes, Wallace). (Lloyd
> Morgan 1895, quoted in Herrnstein 1972, 26)
> 



The next two decades saw no decline in psychologists' interest
in instincts. Between 1900 and 1920 over 600 articles and books were
published on this topic in the USA and England alone (Cravens 1978).
Many of these publications emulated William James' work,
presenting lists of candidate human and animal instincts. However,
these authors often departed from James' developmental account,
viewing instincts instead as emerging fully formed and insensitive to
experience. Lists of candidate instincts also varied dramatically,
with some authors positing as few as two human instincts and others
identifying as many as 110 (L. L. Bernard 1921). William
McDougall's *Introduction to Social Psychology* (1908)
was an attempt to impose rigor to this branch of psychology. McDougall
was critical of his fellow instinct theorists, complaining that
"[h]undreds of passages might be quoted from contemporary
authors, even some of considerable philosophical culture, to
illustrate how these two words ['instinct' and
'instinctive'] are used with a minimum of meaning,
generally with the effect of disguising from the writer the obscurity
and incoherence of his thought" (1908, cited in Herrnstein
1972). McDougall's solution was to define instincts more
precisely as motivational or 'hormic' internal states.
Specifically, he proposed that instincts are:



> 
> an inherited or innate psycho-physical disposition which determines
> its possessor to perceive, and to pay attention to, objects of a
> certain class, to experience an emotional excitement of a particular
> quality upon perceiving such an object, and to act in regard to it in
> a particular manner, or, at least, to experience an impulse to such
> action. (1908, 25)
> 



McDougall went on to posit various learning rules describing how both
the perceptual inputs and the behavioral outputs associated with an
instinct are modified by experience (Herrnstein 1972). Thus, much like
James, McDougall downplayed the distinction between instinctive vs
acquired behavior, focusing instead on the developmental interaction
between instincts (viewed as motivational states) and other factors
such as perception and action. Dewsbury (1993) further notes that, for
McDougall, instincts were psychological processes that interacted with
perceptions, emotions, and behavioral impulses.



McDougall's effort to reform the scientific concept of instinct
was perhaps too little too late, as his work primarily served as
fodder for a group of anti-hereditarian psychologists who emerged in
the early 1920s. Three of the most outspoken critics of instinct were
Knight Dunlap, Luther Lee Bernard, and Zing-Yang Kuo (Guo
Renyuan). Their arguments are worth considering,
especially since many of the same objections would be revived two
decades later in opposition to the ethological concept of
innateness.


### 1.3 Critiques of instinct psychology in the 1920s



One of the first frontal attacks on the concept of instinct was that
of social psychologist Knight Dunlap (1919). He contrasted two general
approaches to the study of instinct. The "physiological"
approach identified each instinct with a distinct neuro-physiological
mechanism. Dunlap was in principle supportive of this approach,
claiming that it could potentially generate useful definitions of
particular instincts. However, Dunlap lamented that, "I am very
strongly convinced that it is not at present possible to secure
agreement to confine the term to this meaning" (1919, 308). The
problem, he thought, stemmed from the prevalence of
"teleological" approaches to instinct, of which McDougall
was a prime example. On the teleological approach, components of
behavior are grouped together as members of a class according to their
tendency to generate some functional outcome. Dunlap cited the
"moral instinct" and "the instinct for
pugnacity" as examples. Dunlap was willing to tolerate this
approach provided that "[t]he grouping of activities into
'instincts' [is] ... clearly understood to be a
device of convenience only, similar to the arrangement of documents in
a well ordered filing system" (1919, 309). Problems emerge, he
thought, when psychologists reified those groupings, regarding them as
natural (as opposed to instrumental) categories. Dunlap argued that
this tendency encouraged psychologists to draw faulty inferences. For
example, "Having posited a 'pugnacious instinct,'
... one writer proceeds gravely to infer that war is forever a
necessity, as the expression of this instinct." (Dunlap 1919,
309). From identifying pugnacity as a natural teleological category,
psychologists inferred that it is developmentally fixed. Dunlap
recognized that this inference was empirically unwarranted.



Social psychologist Luther Lee Bernard (1921; 1924) also thought that
ambiguity in psychologists' use of "instinct"
promoted faulty inferences. As he explained, the typical instinct
theorist, "often confuses both himself and the reader by such
vagueness of speaking, for he may at one time mean only to emphasize
the automatic character of the act and at another he may fall back
upon the recognized or approved meaning of the term, implying that
automatism is an inherited phenomenon" (1921, 101). In other
places, Bernard observed, instinct theorists would take developmental
fixity as a sufficient condition for instinct, with "any
relatively fixed or definite action pattern being pronounced an
instinct whether it is acquired or inherited" (1921, 101). In
addition to such inconsistencies, Bernard accused instinct theorists
of remaining "untouched by the biological foundations of these
sciences... [since] they have failed to grasp the true
significance of Mendelian theory for the social and mental
sciences" (1921, 103). To illustrate, Bernard cited examples in
which instinct theorists would posit the evolution of a
species-typical instinct in just a few generations. Such rapid
fixation violated basic principles of Mendelian inheritance as Bernard
understood them. Bernard envisioned a future for social psychology
"the practitioners of which fully recognized that nature and
culture could not be separated" (Cravens and Burnham 1971,
654-55).



Perhaps the fiercest critic of the concept of instinct was the
Berkeley-educated Chinese psychologist Zing-Yang Kuo (Guo
Renyuan) who was dedicated to a Watsonian vision of
psychology as an experimental science grounded on behaviorist
principles (Honeycutt 2011). Kuo pejoratively referred to instinct
theory as "finished psychology" because it discouraged
researchers from exploring the potential influences of learning early
in an organism's life. As he explained, "[t]he
preconception of instinct has often betrayed the psychologist into
overlooking the new environmental factors which are chiefly
responsible for the supposedly unlearned acts" (Kuo 1921, 653).
In his earlier writings, Kuo (1921) admitted that certain
"hereditary action units" appear early in development and
could be classified as instincts, provided that they are viewed merely
as developmental resources and not as functional behaviors (Honeycutt
2011). However, this admission inspired critics, such as Geiger
(1922), to object that Kuo was implicitly relying on the very concept
of instinct which he purported to reject. This prompted Kuo (1924;
1929) to revise his position, ultimately questioning the very
distinction between heredity vs acquired traits (Honeycutt 2011). His
main argument assumed that in order to identify some behavior as
hereditary (as opposed to acquired), it would be necessary to identify
three things: (1) some fixed behavioral pattern, (2) the
neuro-physiological mechanisms generating that pattern, and (3) a link
to specific germ cells responsible for producing that mechanism. Kuo
maintained that there simply were no fixed behaviors, let alone ones
that could be associated with definite neuromuscular patterns
(Honeycutt 2011). At the same time, available embryological evidence
(e.g. Carmichael 1925) revealed that germ cells do not act
independently of environmental influences during development. Thus,
Kuo concluded that the very idea of a hereditary trait is,
''beyond any experimental approach, and will always remain
as an unverifiable abstraction which serves no scientific purpose
whatever'' (Kuo 1929, 195). A true scientist, Kuo argued,
would not be satisfied with *labelling* behavior
'instinctive' but would demand a causal analysis of its
origin in the embryo, asking 'How are our Instincts
Acquired?' (Kuo 1922, 344)



Few psychologists went as far as Kuo in rejecting the concept of
heredity in psychology (e.g. Tolman 1922). However, the criticisms of
Dunlap, Bernard, Kuo and others led to a rejection of instinct as a
legitimate topic of investigation, at least in North America. This
occurred in conjunction with the rise of behaviorism and its focus on
learning theory as a framework for explaining animal and human
behavior.


### 1.4 Ethology and the revival of instinct psychology



Despite its eclipse by behaviorism in North America, the study of
instinct was rehabilitated in Europe on either side of World War Two
by the founders of ethology, Konrad Lorenz and Niko Tinbergen
(Tinbergen 1942; 1951; Lorenz 1957 (1937); Lorenz and Tinbergen 1957
(1938)). Ethology was a Darwinian approach to behavior and the direct
ancestor of today's behavioral ecology and sociobiology. It
treated an organism's behavior as simply one more evolved
characteristic alongside its skeleton and its digestive system. Innate
behavior was thought to be composed of identifiable units -
'fixed action patterns' - whose evolution could be
studied like that of a bone by comparing the different form taken by
the same (homologous) behavior in different species. The evolutionary
relationships of birds, for example, were thought by the early
ethologists to be reflected in similarities and differences in their
courtship rituals as reliably as in similarities and differences in
their bones.



In their early work, Lorenz and Tinbergen drew a sharp distinction
between innate vs acquired behavior. An innate behavior was thought to
be, (1) stereotyped or constant in form, (2) species-typical, (3)
capable of developing in socially isolated animals, and (4) capable of
developing "fully formed" in animals which had been
deprived of opportunities to practice it (Lehrman 1953). Early
ethologists placed considerable emphasis on the 'deprivation
experiment' as a method for distinguishing innate from acquired
behaviors. These experiments involved raising an animal without the
opportunity to learn a behavior and then testing to see if it can
perform the behavior when provided with an appropriate stimulus. A
songbird, for example, can be raised from egg to adult without hearing
a member of its own species sing, and tested to see which song it
produces the following spring. If it produces the typical song of its
own species, then the song was deemed innate. For more on Lorenz and
Tinbergen's ideas about instinct, see (Richards 1974; Griffiths
2004; Brigandt 2005; Browne 2005; Burkhardt 2005).



The idea of instinct in classical ethology was strongly criticized by
several North American psychologists including Theodore C. Schneirla
(1952; 1963; 1966), Howard Moltz (1960; 1965), and most famously by
Schneirla's student Daniel S. Lehrman in 'A critique of
Konrad Lorenz's theory of instinctive behavior' (1953).
Lehrman objected to ethologists' resurrection of the innateness
concept on both empirical and theoretical grounds. Empirically,
Lehrman documented the role of environmental factors in the
development of species-typical behavior patterns, drawing on many
existing studies, including some by Kuo. These experiments revealed
that certain prototypical fixed action patterns depend on
environmental feedback for their development. This is true despite the
fact that such behaviors are species-typical and present in animals
that were raised in isolation. For Lehrman, such evidence undermined
the attempt to distinguish innate from acquired behavior:



> 
> in each case, analysis of the developmental process involved shows
> that the behavior patterns concerned are not unitary, autonomously
> developing things, but rather that they emerge ontogenetically in
> complex ways from the previously developed organization of the
> organism in a given setting. (Lehrman 1953, 343)
> 



Lehrman was particularly critical of the use of the deprivation
experiment to infer that a certain trait is innate
*simpliciter*, rather than merely that the factors controlled
for in the experiment are not needed for the development of that
trait.



Many of Lehrman's ideas were incorporated into mainstream
ethological theory. By the 1960s Tinbergen regarded the use of the
term 'innate' to characterize behaviors as
"heuristically harmful" (Tinbergen 1963, 425) and endorsed
Lehrman's critique of the deprivation experiment: "The
conclusion can only be formulated correctly in negative terms, in
describing which environmental aspect was shown *not* to be
influential" (Tinbergen 1963, 424). In the same period Tinbergen
and his students shifted the focus of their research from behaviors as
stable taxonomic characters to behaviors as adaptations shaped by the
ecological demands of the environment (Burkhardt 2005). Determining
the extent to which behavior develops independently of the environment
ceased to be important to the Tinbergen school, or to the new
discipline of behavioral ecology in which students of Tinbergen like
Richard Dawkins played such a prominent role. Interest turned instead
to testing population genetic and game theoretic models of behavioral
evolution.



Lorenz responded to his critics with a revised account of the
innate/acquired distinction (Lorenz 1965; see also Browne 2005). No
trait is innate in itself, but "certain parts of the information
which underly the adaptedness of the whole, and which can be
ascertained by the deprivation experiment, are indeed innate"
(Lorenz 1965, 40). A trait is innate insofar as its development is
guided by 'inherited information' rather than
'environmental information.' Lorenz defined
'information' in terms of adaptation. An adaptive trait
'fits' its environment and hence can be said to contain
information about that environment just as a key can be said to
contain information about the lock it will open. The question is where
that information comes from - how does the organism
'know' about its environment? If a woman has calluses on
her palms rather than on the backs of her hands, this represents
information about where her skin gets rubbed most. If she were
*born* with calluses on her palms, as ostriches are born with
calluses that match pressure points on their legs, this would imply
advance 'knowledge' of where her skin is going to be
rubbed most. Such anticipatory information, Lorenz argued, must be in
the genome. It is in the genome as a result of natural selection,
which can be seen as a form of trial-and-error learning.



Lorenz's analysis can readily be expressed in
information-theoretic terms, with the environment as the signal source
and the organism as the receiver. Organisms need to reduce their
uncertainty about what demands the environment will place on them and
to develop in a way that meets those demands. There are two ways to do
this. The first way is to gather information about the environment
during development. The water flea *Daphnia pulex* monitors
chemical traces of predators as it develops. If an individual flea
detects evidence that predators are present, then that flea grows
defensive armor. Thus, a flea's possession or lack of defensive
armour reflects environmental information. The alternative is to
inherit information from your ancestors. The human sickle cell allele
has harmful effects in homozygotes and survives in a population only
because it confers resistance to malaria in heterozygotes. Hence the
fact that an individual carries the allele provides information about
the prevalence of malaria in the ancestral environment and thus,
probably, in the environment of the organism which inherits the
allele. The sickle cell allele can thus be seen as passing on
information about the environment which was 'learnt' by
ancestors through natural selection. To the extent that the functional
adjustment of a trait to its environment is explained by
'inherited information' of this kind, Lorenz argued, the
trait is innate. Hence, albeit in a very different way from Tinbergen,
Lorenz also came to see whether a behavior is an adaptation as the key
issue.


### 1.5 Nativism and the study of language acquisition



Classical ethology flourished in the years immediately following World
War Two (Burkhardt 2005). At the same time others started to question
the emphasis on environmental factors in behavioral development which
had developed between the wars in the wake of the behaviorist
revolution in psychology. Numerous lines of evidence suggested that
psychology would have to take account of species-specific biological
endowments if it was to understand how different species interact with
their environment and the distinctive things each species is able to
learn from these interactions (e.g. Harlow 1953; Tomkins 1962;
Seligman 1970). By far the most influential criticism of behaviorism,
however, came from linguistics. The linguist Noam Chomsky argued that
existing behaviorist accounts of the development of language were
unworkable and offered a general argument for the conclusion that the
ability to acquire language is innate (Chomsky 1957; 1959; 1966).
According to this 'poverty of the stimulus' argument, the
examples of speech to which children are exposed do not contain enough
evidence to settle which utterances are grammatical in the language
they are trying to acquire. Nevertheless, children reliably acquire
the grammar of their native language. Therefore, Chomsky and his
followers concluded, children must have innate knowledge about grammar
which supplements the evidence to which they are exposed during
development. If this argument is sound, every normal childhood is a
deprivation experiment that confirms the innateness of grammar. The
details of the original poverty of the stimulus argument, its
elaboration by Chomsky's followers, and the current state of the
evidence for linguistic nativism are discussed in detail in the entry
 Innateness and Language.
 What matters for current purposes is that Chomsky's work
produced a very broad consensus in psychology that language
acquisition is explained by a complex, evolved mechanism that is
present at birth and which can produce normal linguistic development
in a wide range of environments, including those which are
'impoverished' with respect to language.



The 'language acquisition device' has served as an
exemplar for research on whether other psychological and behavioral
traits are innate. Like the language acquisition device these
putatively innate traits are supposed to explain patterns in the
development of the child's mind. These patterns can be seen as
representing innate 'knowledge' or innate
'theories' about various cognitive domains. For example,
the eminent cognitive developmental psychologists Susan Carey and
Elizabeth Spelke argue that children possess four domains of innate
'core knowledge' which underlie much of their later
cognitive development. These domains are 'objects, agents,
numbers and space' (Carey and Spelke 1996, 517). Children think
about each of these four domains in distinctive ways that do not seem
to depend on the details of the child's environment. The
distinctive way in which children think about living, as opposed to
inanimate, entities has also been proposed as a domain of innate
knowledge (e.g. Medin and Atran 2004). The recent philosophical
literature on the concept of innateness which is outlined in later
sections of this entry is mostly intended to analyse innateness as it
is understood in this extensive body of 'neo-nativist'
psychology. The topic of
 innateness in language
 is covered separately. For a thorough introduction to this field and
the controversies arising from it, also see (Carruthers, et al. 2005;
2007a; 2007b).


### 1.6 Historical patterns



This historical overview of scientific debates over nativism reveals a
few general patterns. One is that there has never been an agreed
scientific definition of an "instinctive" or
"innate" trait. During the late 19th century
C.L. Morgan noted the proliferation of different definitions of
instinct and criticized his contemporaries for their sloppy use of
language. The same criticisms are echoed in the work of Dunlap,
Bernard, and Kuo, who all complained that imprecision in the
definition of "instinct" led researchers to draw faulty
inferences. Lehrman and other critics of the ethological revival of
instinct likewise complained that this concept lacked scientific
precision.



A second general pattern is that such ambiguity was no barrier to the
sheer volume of studies claiming to identify instincts. Indeed, it
might even be the case that lack of precision in the meaning of this
term fostered the growth of the instinct industry in late
19th and early 20th century. A third general
pattern is the persistent complaint that instinct theorists ignore
early or subtle opportunities for learning. Wallace criticized Darwin
for failing to consider the influence of experience in early
development. The same objection can be found in Kuo's criticism
of instinct theory. Lehrman and his fellow critics likewise noted the
failure of ethologists to consider possible influences of experience
on development.



Despite this troubled scientific history, versions of nativism
continue to appear in psychology. In this century, Evolutionary
Psychology has resuscitated a brand of nativism that is strikingly
reminiscent of the instinct psychology that prevailed in the wake of
Darwin and James (Hampton 2004). Part of what makes the recurrence of
nativism philosophically interesting is that many scientists have
noted that the innate/acquired distinction is ultimately a false
dichotomy (Kitcher 2001). All traits are influenced in their
development by both environmental and genetic factors.
Weismann's insistence on the distinction aside, it is a mistake
to classify traits as emanating either from the germ line or the
environment. Moreover, ever since Baldwin (1896) it has been thought
that complex behavioral adaptations can conceivably become fixed in a
population by a process that relies heavily on experience. What then
explains the persistence of the innate/acquired distinction in
psychology? The following section reviews recent attempts by
philosophers to identify what is at issue in disagreements over the
meaning and utility of nativism in psychology and biology.


## 2. Philosophical diagnoses of the scientific debates



The previous section reviewed some of the arguments raised by
scientists about the nature of instinct or innateness and the
questionable scientific utility of this concept. In this section, we
consider some recent proposals by philosophers to capture what is at
issue in these debates. These philosophical diagnoses vary
considerably, not only in their understanding of what is at issue, but
also in their methods. As we will see, this is one of the topics on
which an 'experimental philosophy' (X-phi) approach has
been put to productive use (see
 SEP entry
 on this topic). What follows is a review of five different
philosophical hypotheses about what is at issue in scientific debates
over nativism.


### 2.1 A matter of explanatory emphasis



One possible reason for the persistence of scientific debates over
nativism is that researchers approach psychological development with
different explanatory interests. This idea was defended by Peter
Godfrey-Smith (1996), who distinguished between
"externalist" and "internalist" modes of
explanation in biology generally. Externalists "explain
properties of organic systems in terms of properties of their
environments"; whereas internalists explain, "one set of
organic properties in terms of the other internal or intrinsic
properties of the organic system" (1996, 30 quoted in Cowie
1998, 16). Nativism can be viewed as an internalist mode of
explanation in that it focuses on internal (e.g. genetic)
contributions to development while setting aside environmental
influences. Conversely, anti-nativists like Kuo or Lehrman focus on
certain "external" (e.g. environmental) factors. On this
view, the two approaches are not in conflict. Ultimately, it comes
down to the interests of an investigator where to place explanatory
emphasis.



If this analysis is correct, then the resolution of debates over
nativism should be straightforward. It should be sufficient to point
out that the two perspectives are complementary: that both
"internal" and "external" factors contribute
to development. The problem with this analysis, however, is that it
threatens to trivialize the debate. Could it really be the case that
such intellectual heavyweights as Lorenz and Lehrman were engaged in
nothing more than a verbal dispute? Fiona Cowie (1998), for one, sees
this as a red flag. Although verbal disputes are not unheard of in
science and philosophy it is uncharitable to assume that all
historical debates over nativism can be understood so simplistically.
As Cowie puts it, "[v]iewing nativists and empiricists as
quarreling merely over how 'important' the various factors
in belief and concept acquisition are can incline us to see their
dispute as insubstantial" (1998, 22). We are well advised, she
argues, to search for more substantial stakes in these debates.



More recently, James Tabery (2014) has developed an account of the
"interaction debates" (as he calls them) which also places
explanatory interests at the center of the disagreement. Tabery
identifies two general scientific approaches to the interaction
between nature and nurture. So called "variation
partitioners" understand interaction in statistical terms. Their
explanatory aim is to identify the amount of actual variation
exhibited by some phenotype that can be attributed to additive genetic
variance and environmental factors, respectively. A sharp distinction
between innate versus acquired traits is central to this approach. By
contrast, Tabery's "mechanism elucidators" are
primarily interested in describing the developmental mechanisms
generating particular phenotypes. These researchers understand
"interaction" in causal terms and tend to see little value
in a sharp innate/acquired distinction.



Philosophers Slobodan Perovic and Ljiljana Radenovic (2011) have also
suggested that nativism/empiricism controversies might be dissolved by
identifying the different explanatory interests of the disputants.
They focus on the dispute between neo-nativist psychologists who see
themselves as heirs to Chomsky's linguistic nativism (Section
1.5) and the intellectual descendants of anti-nativist developmental
psychologists (Section 2.4) who believe that the distinction between
innate and acquired behavior is meaningless and that explaining
outcomes of development by calling them 'innate' is
scientifically vacuous (e.g. Oyama 1985; Ford and Lerner 1992; Michel
and Moore 1995). According to Perovic & Radenovic these
anti-nativists or 'developmental systems theorists' target
neo-nativist claims about the pattern of gene-environment interaction
in the development of cognition and behavior. Neo-nativists claim that
the pattern is maturational, with genes as specific causes and
environmental factors as merely "permissive" causes
(Holtzer 1968). This is a fundamentally internalist form of
explanation, with external, environmental factors as mere background
conditions and internal, genetic factors doing the real explanatory
work. However, while neo-nativist psychologists do make such claims,
they do not typically examine the developmental genetics of the traits
which they claim are 'innate' (Gary Marcus (2004) is one
important exception). Instead, their research examines specific stages
in psychological development, often well into the life of the
individual, and specific environmental factors which might be thought
to influence development at those stages. Their experiments aim to
show that the developmental outcome at such a stage is not
specifically influenced by the details of the environment, but instead
follows a pathway determined by internal cognitive structures. In one
famous body of research, children make an 'intellectual
breakthrough' at around age four when they come to properly
understand the whole body of kinship terms in their local language,
rather than treating categories like 'uncle' as defined by
the pattern of resemblance between uncles (Keil 1989). The fact that
this happens all at once, at around the same age, and despite a great
deal of variation in the specific kinship systems that children are
learning, supports the view that this transition is the result of an
internal, maturational change. While an environment of kinship
structures and kinship terms is needed, it functions as a merely
permissive or background condition. The explanatory work is done by
the internal factors.



Perovic & Radenovic (2011) point out that this claim about the
causal structure of development in a particular, late developmental
stage is entirely compatible with the strongly interactionist view of
how genes and environment build the brain favoured by developmental
systems theorists. They suggest that neo-nativism is primarily
concerned to show that how organisms respond to their environments
depends strongly on cognitive structure that is in place before the
organism encounters that environment. Conversely, anti-nativists are
primarily concerned to show that environments often play a specific,
instructive role in the development of cognitive structures. Since the
two schools do such different research, the latter primarily focused
on human development post-partum and well into childhood, and the
former on early development, often in animal models for reasons of
ethical and experimental tractability, there is considerable scope for
accounts of psychological development that draw on both perspectives
at different stages of development. So, once again, on this account
disputes about nativism are fundamentally a reflection of scientists
different explanatory interests.


### 2.2 Special-purpose faculties and the limits of empiricist science



The question, "what are nativism debates about?" has been
carefully analyzed by Fiona Cowie (1998), who distinguishes two
arguments historically deployed in defense of nativism. *Poverty of
the stimulus arguments* claim that the environment lacks
sufficient information for an organism to learn some belief, cognitive
disposition, or behavior. If an individual nonetheless acquires that
cognitive trait, then the process must have involved some amount of
"innate" information. A second type of argument, which
Cowie (1998) calls *impossibility arguments*, claim that
certain traits must be innate not because the environment is
impoverished, but rather because scientific accounts of the
acquisition process are doomed to failure. This distinction leads
Cowie (1998) to propose two fundamental disagreements underlying
debates over nativism. The "special faculties" debate
concerns the basic architecture of the mind. Nativists posit
special-purpose learning faculties to explain acquisition, whereas
anti-nativists explain acquisition in terms of domain general
learning. The "mystery" debate, however, turns on a
skeptical claim about the limits of scientific explanation. As Cowie
explains:



> 
> Impossibility arguments... work to undermine the empiricist
> assumption that the processes underpinning our acquisition of ideas
> and beliefs are simply a species of natural phenomena, amenable at
> least in principle to natural scientific explanation. (1998, 50)
> 



Cowie is describing an extremely strong form of anti-empiricist
skepticism. When directed at the explanatory prospects of science in
general it is unlikely that this brand of nativism will be appealing
to naturalistic philosophers or scientists. However, skepticism of
this kind may be directed at specific scientific theories or
explanatory frameworks. Cowie (1998) discusses Jerry Fodor's
(1975; 1981) peculiar-sounding hypothesis that most concepts -
e.g. our concept of a doorknob - are innate. On Cowie's
reading, Fodor is offering an impossibility argument: concept
acquisition cannot *in principle* be explained by an empiricist
model of associative learning. The following section (2.3) looks more
closely at psychological primitivism, a more developed version of
Cowie's mystery hypothesis. The remainder of this section
focuses on the special-faculties hypothesis.



Cowie (1998; 2009) acknowledges a limitation of the special-faculties
hypothesis. It applies only to debates in *psychology* over the
kinds of learning process underlying the acquisition of beliefs or
behaviors. This is a problem because disputes about nativism are not
confined to psychology. For instance, we saw in the previous section
that Weismann (1891 (1888)) drew a sharp distinction between
hereditary versus acquired traits generally. The special faculties
hypothesis apparently cannot explain such non-psychological
disputes.



One potential way of rescuing the special-faculties hypothesis is to
underscore the difference between nativism in psychology compared to
innateness hypotheses in other disciplines, such as biology. Richard
Samuels (2002), who does not defend the special-faculties hypothesis,
nonetheless maintains that innateness is a distinctively psychological
concept. According to Samuels, to identify some trait as innate means
above all that it is unlearned, and to identify some trait as learned
implies that it is not innate. Samuels (2002) calls this the
*fundamental conceptual constraint* on any analysis of
innateness. If Samuels is correct on this point, such that questions
about nativism are ultimately about the presence/absence of learning,
then it is no shortcoming of the special-faculties hypothesis that it
focuses on psychological traits. One noteworthy difference between
Cowie's special-faculties hypothesis and Samuels'
fundamental constraint is that the former distinguishes among learning
"mechanisms" (general vs special purpose), whereas the
latter distinguishes more broadly between learned versus unlearned
traits.


### 2.3 Innateness as a psychological primitive



Richard Samuels (1998; 2002; 2004; 2007) has developed a version of
Cowie's mystery hypothesis called psychological primitivism. On
this view, that a belief or behavior is 'innate' means
that it serves as an explanatory primitive for psychological science.
An explanatory primitive is a concept that is deployed by a discipline
to explain certain phenomena, but which cannot in principle be
explained by that discipline. Samuels maintains that there is a sharp
explanatory boundary between psychology and other fields. A necessary
condition for any psychological explanation, he claims, is that it
apply to the whole organism and not to a specific (sub-personal)
component (Samuels 1998). This condition excludes many explanations
couched in neurobiological terms, because they apply to sub-personal
components and not to the organism as a whole. However, there are
other predicates that apply to the whole organism and yet do not
qualify as psychological (e.g being a carnivore). So, the
personal/sub-personal distinction is not sufficient for marking the
boundary that Samuels wants to draw. As a result it is not entirely
clear how to draw the line between psychological and non-psychological
phenomena. Samuels examples of psychological explanations feature
processes such as conditioning, perception, and inference; whereas
neurological and hormonal explanations purportedly fall outside
psychology (Samuels 1998; 2002; 2004). Some authors criticize
Samuels' primitivism on the grounds that this sharp distinction
between psychology and other sciences does not exist (Gross and Rey
2012; Linquist 2018). For example, psychological explanations of
depression and anxiety cite both intentional states and sub-personal
processes as components of the same mechanism. The issue of how
psychological explanations are related to biological explanations is
one of the most pressing questions in the philosophy of cognitive
science and has recently been explored in the context of debates over
mechanistic explanation (see Gaj 2016; Milkowski, et al. 2019 for
reviews).



A further problem with Samuels's primitivism is that some
"biological" (i.e. not psychologically explainable) events
can have pronounced psychological effects over an individual's
lifetime. For example, someone who undergoes brain trauma or suffers
from the overuse of pharmaceuticals might thereby acquire certain
beliefs or behaviors. Phineas Gage, the 19th century
railroad worker who became famous for surviving a massive brain
injury, is reported to have acquired several new personality traits
after an iron rod pierced his prefrontal cortex (Twomey 2010). Samuels
worries that according to primitivism such traits would be innate
since they cannot, by hypothesis, be explained in psychological terms.
He worries that this would be highly counterintuitive.



To avoid such implications, Samuels shores up his proposal with a
proviso: a psychological structure is innate just in case it is
psychologically primitive and it *would develop under normal
conditions for a member of the species*. This move has prompted
some philosophers to generate further counterexamples of acquired
traits that are psychologically unexplainable but nonetheless emerge
under "normal" conditions (e.g. Khalidi 2007). A deeper
question, however, concerns the very notion of a "normal"
developmental environment. Spelling out this idea is no easy matter.
Presumably, a necessary condition for some environment to qualify as
normal for a species is that it was encountered ancestrally. But this
raises the twin problems of how far back in time is relevant, and how
can we classify environments as types. Samuels argues that these
problems plague any discipline that appeals to the notion of a normal
environment and are thus not unique to psychology. However, it remains
an open question whether the concept of normal environment can made
coherent. We return to this issue in Section 3.4 (below).


### 2.4 I-properties and the clutter hypothesis



As we discussed in Section 1, for more than 150 years there has been
disagreement over how to define instinctive (or innate) traits in a
way that is useful to scientific psychology. Shortly after instinct
had become a topic of scientific study, C.L. Morgan (1896) identified
seven "definitional" issues surrounding this term. Two
decades later, criticisms by Knight Dunlap (1919) and L.L. Bernard
(1921) reveal that those ambiguities had not been resolved. It is also
telling that Lorenz continued to modify his definition of innateness
in response to critics over the course of his career, while Tinbergen
eventually abandoned this term altogether. More recently, behavioral
biologist Patrick Bateson has observed that, "[a]t least six
meanings are attached to the term [innate]: present at birth; a
behavioral difference caused by a genetic difference; adapted over the
course of evolution; unchanging throughout development; shared by all
members of a species; and not learned" (1991, 21). His objection
is not merely that the term "innate" is ambiguous. Like
Dunlap (1919) and Bernard (1921), his complaint is that ambiguity
promotes equivocation, encouraging researchers to draw faulty
inferences as they slide between different senses of innateness. For
example, if a trait is deemed "innate" because there is
evidence that it is present at birth, psychologists will sometimes
infer (without further evidence) that it is therefore
"innate" in the sense of being insensitive to
environmental influence. Developmental biologists since Kuo (1921)
have provided evidence against this easy inference. Bateson's
own work on the phenomenon of parental imprinting in birds (Bateson,
1966) showed that traits which appear early in life are often highly
sensitive to specific environmental factors. The tendency for nativism
to promote such unwarranted inferences has been one of the main
reasons why many scientists have called for dramatic revision or even
an elimination of this concept from scientific discourse (see Section
4.5 of this entry).



Paul Griffiths (2002) has clarified what is ontologically at stake in
this objection to nativism. Researchers who draw questionable
inferences about the properties associated with innateness are
assuming (implicitly, if not explicitly) that innateness is a natural
kind. More specifically, they assume that innate traits form what
Richard Boyd (1989) called a *homeostatic property cluster*.
Such property clusters require the existence of some causal process
that "holds together" the relevant properties in a
coherent bundle, so to speak. For example, Weismann assumed that the
only way for a trait to be modified by natural selection is if it
develops "directly" from germline cells. He also assumed
that germline cells were the only possible source of developmental
stability since environmental factors were seen exclusively as a
source of developmental noise (Johnston 1995). Thus, on
Weismann's picture, the properties of being an adaptation and
being developmentally stable were a part of the same homeostatic
cluster. It turns out that Weismann's picture of development was
too narrow. The environment is much more than just a source of noise.
Certain environmental factors are a source of developmental stability
(West-Eberhard 2003), acting as a "scaffold" for the
development of particular traits (Sterelny 2003). The environment can
also store information that organisms rely on during development to
generate adaptive phenotypes (Mameli 2004). So, contra Weismann, there
is no distinct causal process associated with germline cells that
accounts for developmental stability and adaptation. Without a known
process to unify the various properties associated with innateness,
Griffiths (2002) argues, the assumption that they form a homeostatic
cluster is unwarranted.



This position was developed in Bateson's later work with
philosopher Matteo Mameli (Mameli and Bateson 2006; 2011; Bateson and
Mameli 2007). Expanding on Bateson's (1991) original list, they
identify a total of twenty-six candidate definitions of innateness in
the scientific and philosophical literature (Mameli and Bateson 2006).
Many of these proposals are deemed unsatisfactory because "they
appeal to unclear, unexplained, or controversial notions such as
'genetic information', 'learning',
'developmental induction', and 'normal
development'" (2006, 176). Other candidate definitions are
rejected by Mameli and Bateson because they fail to pick out any trait
whatsoever. For instance, no trait is (strictly speaking) genetically
determined or unacquired. Other candidates are rejected because they
apply to all possible traits. For example, every trait is (to some
degree) genetically influenced or insensitive to the environment. By
the end of their analysis, Mameli and Bateson arrive at a shortlist of
just eight candidates. These "i-properties" (as they call
them) are relatively promising definitions in that they suffer from no
obvious conceptual or empirical shortcoming. Their shortlist of
candidate definitions for "innate" are as follows:


1. It appears reliably at a particular stage of the lifecycle.
2. It develops abnormally in response to environmental manipulations
which were not encountered in the organism's evolutionary
history.
3. It is not produced by a developmental mechanism that evolved to
generate different phenotypes in response to particular environmental
conditions (i.e., adaptive phenotypic plasticity), and it is also not
the result of exposure to abnormal environmental conditions.
4. Any modification to the trait would have a negative impact on the
development of other traits (the 'generatively
entrenchment' of Schank and Wimsatt 1986).
5. It is insensitive to certain environmental changes during
development.
6. It is insensitive to certain environmental changes after
development.
7. The trait is species typical.
8. The trait is a standard Darwinian adaptation.



Mameli and Bateson maintain that it is an empirical question whether
any of these properties cluster together. Moreover, they propose that
in the absence of a known unifying causal process, we should not
assume that they do cluster. Mameli (2008) has dubbed this the
"clutter hypothesis" (in contrast to "cluster
hypothesis"). Their work has inspired some recent philosophical
discussion over which hypothesis (clutter or cluster) is best
supported by available evidence and theory. For instance, Nicholas
Shea (2012) argues that recent developments in evolutionary and
developmental biology suggest that i-properties do not cluster. In
contrast, Muhammad Ali Khalidi (2016) argues that innateness
properties *do* cluster provided that we focus strictly on
psychology and not biology (assuming that such a distinction can be
drawn). This question remains an important area for future
research.



Although the clutter hypothesis captures what is ontologically at
stake in debates over nativism, it does not explain why the associated
conceptual confusion has been so difficult to resolve. Admittedly,
ambiguities are by no means unknown to science (Cowie 2009; Samuels
2007). However, the tenacity of nativism debates in psychology seems
unusual. One might reasonably expect that psychologists would have, by
now, disambiguated this concept and developed experimental criteria
for detecting specific i-properties. Such questions as whether a trait
is present at birth, a functional adaptation, developmentally
sensitive to some environmental factor, and so on should be regarded
by psychologists as independent research hypotheses (Griffiths 2002).
On the contrary, there is a stubborn tendency to conflate these issues
by simply asking whether some trait is "innate." Even
among researchers who acknowledge on the one hand that
"innate" is a multiply ambiguous term will, in other
contexts, slide between different i-properties apparently without
realizing it (Linquist et al. 2011). Such observations have prompted a
number of recent questionnaire experiments, conducted largely by
philosophers, analyzing the "folk" concept of innateness
and comparing it to scientific conceptions.


### 2.5 Folk essentialism and the psychological attraction of nativism



Griffiths (2002) offered a testable psychological hypothesis to
explain the recalcitrance of nativism in psychology and potentially
other disciplines. The basic idea is that the concept of innateness is
a cornerstone of "folk biology" (Medin and Atran 1999;
2004), the pre-theoretical beliefs that people intuitively use to
understand biological systems. Part of folk biology involves the
classification of organisms into species-like groupings. These
classifications sometimes overlap with scientific classifications, but
often they diverge. For example, a folk biological classification
might identify horses, roses, and octopuses as species-like groupings,
when in fact each of these biological categories contain numerous
species, some of which are morphologically and phylogenetically
disparate.



Folk biology also departs from scientific classification in its
essentialist commitments. Across a wide range of cultures, people tend
to assume that members of each species possess a common essence or
causal nature that determines their appearance, behavior, and
ecological roles (Medin and Atran 2004). Psychologists have found that
even when people have no specific ideas about the nature of a
particular species, they nonetheless assume that it must have an
essence (i.e. they operate with what Medin and Ortony (1989) call an
"essence placeholder"). It is plausible that folk
essentialism has served our species well for most of its history.
Medin and Atran (2004) propose that the existence of an essence
placeholder might have motivated people to explore their environments,
leading them to discover and share information about edible or
medicinal plants, about dangerous plants and animals, and other
salient aspects of the environment. The idea of an essence might also
have assisted humans in tasks associated with agriculture and animal
husbandry. Despite its utility, however, essentialism is
scientifically inaccurate. No internal essence explains why members of
a species share certain traits. Although genetic similarities account
for some of the traits that are typical of a species, it is misleading
to think of a species' genome as its essence. Elliott Sober
(1980) provides a detailed account of what is wrong with this idea.
Essentialism, he notes, employs a Natural State Model of explanation
which views every member of a species as directed toward a single
developmental outcome (natural state). Essentialists recognize that
individuals vary in the characteristics they actually express.
However, such variability is explained according to essentialism by
positing the effects of intervening forces that interrupt development
and prevent the full realization of its goal. The reason that
individuals of the same sex differ in their sexual preference, on this
view, is because of slightly different environmental factors impinging
on the development of these individuals. By contrast, on a
neo-Darwinian model there is no natural state. Individual variability
is partly explained in terms of genetic variation passed on from one
generation to the next. Moreover, even given a specific genetic
starting point, development is not aiming at some specific, natural
state, but simply goes wherever local causes push it. The interaction
between genetic and environmental factors is most accurately
represented as a norm of reaction (see Section 3.2 below), where a
spectrum of developmental outcomes is associated with each unique
genotype in a population of genetically variable individuals. This
neo-Darwinian perspective requires a fairly dramatic shift in
conventional thinking about species. As Atran et al. (2002, 32) put
it, "to understand modern biological science, people must
*unlearn* universal dispositions to view species
essentialistically".



Griffiths (2002) hypothesized that folk essentialism might be exerting
an influence even on scientists' and philosophers'
professional judgments about innateness. More precisely, the
hypothesis states that (1) there is a "folk" or vernacular
concept of innateness that most people operate with in non-technical
contexts, (2) this vernacular concept is incompatible with scientific
developments in such fields as evolutionary and developmental biology,
and (3) that researchers working in psychology and perhaps other
disciplines will employ the vernacular concept of innateness (often
inadvertently) even when reasoning in a scientific context. Machery et
al. (2019) have more recently dubbed this the "attractor
hypothesis" of innateness, because of its similarity to the idea
of a psychological attractor in cultural evolution (Sperber 1996;
Claidiere and Sperber 2007). An implication of the attractor
hypothesis of innateness is that the concept of an innate trait will
be highly resistant to scientific revision. Despite attempts to refine
the concept, researchers will continue to default to the vernacular
concept, the theory goes, and draw faulty inferences despite their
efforts to avoid equivocation. Griffiths (2002) draws the normative
conclusion that the concept of innateness should be self-consciously
eliminated from scientific discourse. This proposal will be discussed
below (Section 3.5). The remainder of this subsection discusses recent
experimental evidence surrounding the attractor hypothesis of
innateness.



Philosophers have devised a number of questionnaire studies exploring
the structure of the vernacular concept of innateness (Griffiths, et
al. 2009; Linquist et al. 2011; Knobe and Samuels 2013) and whether
the vernacular concept features in scientists' judgments about
innateness (Knobe and Samuels 2013; Machery et al. 2019). Drawing
again from the psychological literature on folk biology, Griffiths et
al. (2009) identified three features that are thought to be central to
the vernacular concept of innateness:


* Fixity: Innate traits are insensitive to environmental influences
during development.
* Typicality: Innate traits are shared by most adult members of the
same species or sex.
* Function: Innate traits serve some purpose or end for the
organism.



The authors tested this "three feature theory" (as they
call it) using a questionnaire describing examples of birdsong that
differed in Fixity, Typicality, and Function. The aim was to determine
the extent to which each factor *independently* contributes to
folk judgments about innateness. This experiment was first conducted
on naive or non-expert subjects with the aim of first determining
the structure of the vernacular concept before examining its potential
role in expert (scientific) judgments. As predicted, evidence of
Fixity was enough for naive subjects to agree that a trait is
innate, even if the trait lacks Typicality and Function. Evidence of
Typicality also independently drove innateness judgments, as did
Functionality (though to a lesser degree). The authors take these
results to provide a fine-grained analysis of the vernacular concept
of innateness, revealing just how easily people are prompted to
classify a given trait as "innate." In a later study,
Linquist et al. (2011) expanded the survey to test whether Fixity,
Typicality, and Function also influence naive subjects'
judgments about whether a trait is "in the DNA." They
found that the two phrases ("innate" and "in the
DNA") draw upon the same underlying folk concept. Linquist et
al. (2011) also cite examples where researchers in psychology and
biology employ the folk concept in drawing unjustified inferences
among i-properties. It is important to note that although these x-phi
experiments are quite limited, their findings are confirmed by a much
larger body of experimental work in social psychology on the
'genetic essentialist framework' in folk cognition
(Dar-Nimrod and Heine 2006; 2011; Cheung, et al. 2014). For a side by
side-comparison of the two models see Stotz and Griffiths (2018).



Linquist and collaborators (2011) predicted that scientists would
continue rely on the vernacular concept of innateness when reasoning
in a professional context. This prediction was confirmed by Knobe and
Samuels (2013) who compared naive subjects' responses to
the same birdsong questionnaire that was developed by Griffiths et al.
(2009). As the attractor hypothesis predicts, they found that
scientific training had no effect on a person's judgments about
innateness. Scientists were just as likely as lay people to classify a
trait as innate it if exhibits one of Typicality, Fixity or Function.
This result went against Knobe and Samuels (2013) own expectations
that professional scientists would exhibit a different response
pattern from laypersons. A subsequent analysis of Knobe and
Samuels' (2013) data by Machery et al. (2019) took a
finer-grained look at how different categories of scientist responded
to questions about innateness. They found no significant difference
among psychologists, linguists, and biologists in their responses to
the birdsong questionnaire. This finding supports the attractor
hypothesis and goes against the rival expectation that the concept of
innateness functions differently in psychology or linguistics than it
does in biology. Interestingly, however, Knobe and Samuels (2013) also
asked researchers how "important" the concept of
innateness is in their discipline. In this case, there was a
significant difference among disciplines, with biologists ranking it
less important than psychologist or linguists.



One must be cautious before reading too much significance into these
results since the sample size of scientists was fairly small (Machery
et al. 2019), the questionnaire offered only a limited glimpse into
the folk concept of innateness (Samuels 2016), and the questions
presented (on birdsong) might have been more familiar to certain
disciplines (e.g. to biologists) than they were to others. This topic
is ripe for future research. That said, a few additional results
reported by Knobe and Samuels (2013) are worth mentioning.



In one of their experiments the authors manipulated the way in which
birdsong was described. In one condition, birds were described as
"learning" their song. In another condition, the same
acquisition process was described in neurological terms: birds were
described not as learning their songs, but rather as acquiring songs
through specific neurological interactions with the environment.
Recall that primitivism (Section 2.3) predicts that a trait described
as "unlearned" should be less likely to be seen as innate
than one which is described as the result of a sub-personal,
neurological process. The fact that subjects responded no differently
to the "learned" versus "neurological"
versions of the questionnaire (regardless of whether they were
scientists or lay persons) contradicts this prediction of primitivism.
It is also interesting to note that Knobe and Samuels (2013) found an
effect of moral "valence" on innateness judgments. If a
behavior was morally unacceptable, subjects were less likely to judge
it as innate than if it was morally good. This result ties in with a
broader literature on the influence of moral valence on all manner of
folk judgments (Knobe and Mendlow 2004; Cushman, et al. 2008; Petit
and Knobe 2009). Finally, Knobe and Samuels (2013) included another
version of the birdsong questionnaire in which subjects were told how
different vignettes varied from one another, while also prompting
subjects to justify their responses. This was interpreted by the
authors as a "reflective" condition, with the aim of
prompting subjects to answer more systematically. Knobe and Samuels
(2013) report that subjects responded more systematically under the
"reflective" condition than they did under the
unreflective one, suggesting that even naive subjects will be
less likely to equivocate in their judgments if they are prompted to
do so (see Linquist 2018 for a discussion of this result). All of the
experiments reported in this section are suggestive and offer an
interesting example of how empirical methods can be used to analyze
both folk and scientific concepts. Hopefully other researchers will be
inspired to carry this work forward.


## 3. Revisionist and Eliminativist Proposals



Philosophers have suggested three ways to avoid future iterations of
the nature versus nurture debate. First, revisionist proposals aim to
restrict the definition of "innate" to a subset of the
i-properties outlined by Mameli and Bateson (see Section 2.4). 
Perhaps if scientists converge on a single meaning, problems
associated with equivocation will decrease, and psychology generally
will undergo conceptual progress. Second, eliminativist proposals
argue that while conceptual revision sounds like a nice idea it is
unlikely to succeed. A more practical approach, eliminitivists
suggest, is to discard innatness as a serious scientific construct. A
third strategy, outlined by Cowie (2009) is to do nothing. Vagueness
around the innate acquired distinction has caused, on her view, no
inhibition to scientific progress. In this section we review some
recent revisionist proposals, attempts to establish a single, clear
definition. Eliminativism and the "do nothing" proposals
are considered in Section 3.5.


### 3.1 Innateness as genetic specification



According to our intuitive or "folk" conception of
innateness, a trait qualifies as innate if it is either typical of
most members of the species, or if it is developmentally buffered
against certain environmental factors, or if it is an evolutionary
adaptation (Griffiths, et al. 2009). It might be argued that all three
of these properties are coextensive with traits that are genetically
specified: 1. Species-typicality is explained, on this view, by the
fact that members of each species share a common pool of genes. 2.
Some genes are developmentally buffered against certain environmental
factors, such that within some range of variation those factors do not
impact the expression of those genes. 3. Finally, many biologists see
the gradual accumulation of genetic mutations as the primary mechanism
allowing phenotypes to undergo evolutionary adaptation. Putting these
ideas together, it might seem plausible to cash out the folk
conception of innateness in terms of genetic information. More
precisely, a trait could be described as more or less innate depending
on the extent to which its development is guided by genetic
information. One potential advantage of this analysis is that it can
make sense of the dispositional nature of certain "innate"
traits. Many traits have a late developmental onset, such as those
associated with puberty in humans. Their developmental fixity, their
species typicality, and their functionality can lead people to judge
these traits as "innate" despite not being present early
in life. This judgment makes sense if innate traits are those which
are genetically specified, since the genetic predisposition to develop
certain characters is present in the organism from conception.



Despite these apparent advantages, most philosophers reject this
proposal. As Elliott Sober (1988; 2000) points out, when speaking
about a particular trait in a particular organism - such as the
reader's own height - it makes no sense to ask how much of
that individual trait was determined by genes and how much by the
environment. All traits require both genetic and environmental factors
for their development. Thus, one cannot isolate these causal factors
in a way that would allow for the comparison of their relative
phenotypic contributions. We cannot ask, for example, how an organism
would develop in an "environmental vacuum" because it
would not develop at all. Sober further notes that genetic and
environmental contributions are incommensurable. If you are six feet
tall, we cannot sensibly ask how much of your height came from your
genes and how much came from your environment. There are no
"height particles" produced by both genes and environments
that add up to determine your height (Sober 1988). Genes and
environment both make contributions, but not contributions that can be
taken apart and then weighed separately. Yet the folk concept of
innateness clearly applies to particular traits in particular
individuals: Donald Trump's eyes are innately grey-blue but his
skin is not innately orange. Such statements cannot be meaningfully
translated into statements about the relative contributions of genes
end environment to Trump's eyes or Trump's skin.



The scientific discipline that does meaningfully address questions of
the relative contributions of genes and environment is quantitative
genetics. It does so by shifting its focus from the individual to the
population. Instead of investigating individuals, quantitative
geneticists focus on *populations* comprised of genetically
variable individuals. Instead of asking how genetic and environmental
factors influence the development of an individual, this discipline
focuses on how each factor influences *phenotypic differences*
in a population. It is important to understand how this focus on
population-level phenotypic differences impacts judgments about
whether a given trait is "genetic." An obvious limitation
of this approach is that it can be applied only to traits that exhibit
phenotypic variation. Take some trait that is invariant, such as all
humans having one head. Without variation in this trait, it is not
possible to conduct a population-level analysis to determine the
extent to which this trait is genetically encoded. There are no
phenotypic differences at the population level, and so no
distinguishable genetic contribution to those differences (see
 SEP entry
 on heritability). This is, again, at odds with our vernacular notion
of innateness, which would surely judge the human head to be an innate
trait. Indeed, typicality (or invariance) is one of the driving
factors in folk judgments of innateness (Griffiths, et al. 2009), so
the conventional scientific method for evaluating genetic
contributions to trait development is at odds with our folk intuitions
for this reason alone.



Another implication of this approach is that judgments about the
magnitudes of genetic vs environmental contributions are relative to a
specific population and to a particular environment. Changing either
one of these contextual factors can alter the extent to which some
trait is deemed genetic. For example, suppose that a quantitative
geneticist is interested in growing large corn plants. She sets out to
compare two different corn genotypes (G1 and G2) across two different
fertilizer treatments (E1 and E2). Suppose that G2 grows larger than
G1 by exactly 5 units in both E1 and E2. This would lead our
researcher to conclude that the observed variation in corn height is
due entirely to genetic differences. We might further infer that the
trait of height in corn plants is more strongly influenced by genetic
than by environmental factors. However, this judgment is contingent on
the comparison class that our researcher has chosen. Imagine another
scenario in which G2 is compared to yet another genotype (G3). This
time, our researcher compares E2 to E3, a third fertilizer treatment
distinct from E1. Further suppose that G2 and G3 grow to the same
height in E2, but that G3 is five units larger than G2 in E3. In this
case, a comparison based on population differences suggests that the
focal trait is more strongly influenced by environmental than by
genetic factors. Let us now focus just on G2 in E2, and ask whether
height in these corn plants is more strongly influenced by genetic or
environmental factors? Sober (1988) uses a similar example to
illustrate that any answer to this question is contingent on the
comparison class one chooses. If we compare G2/E2 to G1/E1, then
height differences come out as genetically influenced; but if we
compare G2/E2 to G3/E3, then height differences come out as
environmentally influenced. Hence, judgments about the relative
magnitudes of genetic versus environmental contributions are
inherently "non-local" or context sensitive.



Some philosophers take this as sufficient grounds for rejecting any
analysis of innateness in terms of genetic contributions (e.g. Khalidi
2007). The worry is that there is no canonical comparison class for
evaluating the relative contributions of genetic and environmental
influences. Different researchers will select different alleles and
different environments for investigating a given trait and there is no
non-arbitrary way to determine which is the "correct"
comparison class. Insofar as innateness is not a context sensitive
concept, but the magnitude of genetic contribution is highly context
sensitive, innateness cannot be defined as magnitude of genetic
contribution. One way to potentially avoid this implication is by
specifying a canonical or "normal" range of environments.
In this view, a trait is relatively innate to the extent that genetic
(as opposed to environmental) factors explain phenotypic differences
across the normal range of environments. This proposal will be
considered more carefully in the following section (Section 3.2)
Interested readers might refer to entries on
 Gene
 and
 Biological Information).



Another way to potentially avoid the context-sensitivity objection is
to develop some other method of quantifying genetic vs environmental
contributions to phenotypes. We saw earlier (Section 1) that Lorenz
attempted to define innate traits in terms of the extent to which they
are encoded by genetic *information*. This proposal places
emphasis on the concept of information and whether it is possible to
compare traits according to the relative amounts to which they are
structured by genetic information. A general problem with this
approach is that genes do not contain information about traits,
strictly speaking. As Peter Godfrey-Smith has noted, 'All the
genes can code for, if they code for anything, is the primary
structure (amino acid sequence) of a protein' (Godfrey-Smith
1999, 328). Considered as a language, the genetic code can only refer
to the twenty-three standard amino acids and can only say which order
to put them in. The only exceptions to this are the
'start' and 'stop' codons which affect where
DNA transcription begins and ends. Many other things happen as a
downstream causal consequence of the order of amino acids, but to
paraphrase Godfrey Smith's argument, genes do not 'code
for' these downstream causal consequences for the same reason
that President Nixon's order to cover up the Watergate scandal
was not an 'order' to get himself impeached by Congress.
'Coding for', like 'ordering' and other
semantic locutions, is not merely another name for
'causing'. The idea that the 'genetic program'
or 'genetic instructions' for phenotypes are literally
written in the genetic code is a continuing barrier to the public
understanding of genetics, one that is reinforced every time a
journalist reports that scientists have 'decoded' the gene
for something. In reality there are no tiny 'traitunculi'
hidden in the genome awaiting a sufficiently powerful genetic
microscope to read them (Schaffner 1998, 2016).



But although the sequences of nucleotides in the genome do not
literally 'code for' phenotypic traits, they are, of
course, amongst the causes of phenotypic traits. Several philosophers
and scientists have introduced technical definitions of 'genetic
information' based on these causal relationships in order to
explicate the intuitive idea that genes carry information about
phenotypes. These proposals are discussed in more detail in the entry
 Biological information.
 Here we will simply make two points about these proposals. The first
point is that there are some very straightforward senses in which
genes 'carry information' about phenotypes. The human Y
chromosome carries information about sex in the same way that
'smoke means fire': one can be predicted from the other.
In addition, the SRY region on the Y-chromosome is an adaptation for
making organisms into males, so we can apply a version of
'teleosemantics', an approach which defines information in
terms of adaptation, to this piece of DNA (Sterelny, et al. 1996; Shea
2007 and see the entry on
 Teleological Theories of Mental Content).
 The second point is that these straightforward senses of
'information' also seem to be applicable to environmental
causes in development (Oyama 1985; Griffiths and Gray 2005). Mammals
have a chromosomal system of sex-determination. But many reptiles use
temperature, an environmental signal, to switch genetically identical
eggs between male or female developmental pathways. Other reptiles
have a genetic system which can be overridden by an environmental
signal. Some fish even switch sex in adulthood in response to
environmental cues. These environmental signals carry information
about sex in the same unproblematic 'smoke means fire'
sense as the SRY gene. Moreover, the behaviors that parents use to
give appropriate cues to their eggs, and some of the products of those
behaviors, such as nests of rotting vegetation which maintain a
suitable temperature range, are designed by natural selection to
ensure the correct sex-ratio in offspring, so the teleosemantic
program can be applied to them too. The idea that genes 'carry
information' about phenotypes in a special sense which
distinguishes them from other causes is not the piece of common-sense
it is often taken to be, but rather a highly contested idea that is
the focus of much work in the philosophy of biology. See the entry on
 Biological Information.


### 3.2 Developmental invariance and the norm of reaction



The previous section touched on the fact that judgments about the
relative contributions of genetic vs environmental factors to trait
differences are context sensitive. They are sensitive to both the
allelic combinations that a researcher studies and also to range of
environments that a researcher includes in her analysis. Quantitative
geneticists recognize that a given genetic variant (allele) will have
variable phenotypic effects across different environments. These
responses are often nonlinear, such that gradual increases in an
environmental parameter do not have correspondingly gradual phenotypic
effects. At the same time, different genetic variants (alleles)
compared against a single environment will often produce a range of
phenotypic effects. Quantitative geneticists typically represent these
interactions with a graphical tool called the norm of reaction. These
diagrams were introduced at around the same time as the idea of the
gene and the distinction between genotype and phenotype (Sarkar 1999)
and have long been advocated as the clearest way to think about the
role of genes in development (Hogben 1933; Lewontin 1974; Gottlieb
1995; Kitcher 2001). Suppose, for example, that with respect to some
environmental variable (E) an organism with a given genotype (G1) will
develop the same phenotype (P) way no matter what value the
environmental variable takes (Figure 1).



![Graph of P vs E with two straight horizontal lines labeled G1 and G2. G1 is above G2.](figure1.png)

Figure 1. A norm of reaction in which
the phenotype P is 'genetically determined'




If a norm of reaction has this shape, we can say that P is
'genetically determined' even though it has an
environmental factor as one of its causes. Philip Kitcher suggests
that some norms of reaction may have this form, but only in some
limited, but perhaps contextually important, range of environments
(Kitcher 2001). For example, a disease caused by the loss of one or
both normal copies of a gene might develop in *every*
environment except those specifically structured as clinical
interventions to cure the disease.



Another norm of reaction is one in which genetic and environmental
factors interact 'additively' (Figure 2). Genotype makes a
*constant difference* across some range of environments. While
the genetic variable does not determine the actual value of the trait
in each individual, it does determine the differences between
individuals. Moreover, when the norms of reaction have this form,
heritability scores become relevant to the question of whether and how
much a phenotype can be altered by environmental intervention, as
discussed in the previous section. A famous diagram in the early days
of behavior genetics depicted the relationship between IQ (P),
genotype (G) and the 'enrichment' of the environment (E)
as having roughly this form (Gottesman 1963a). If correct, this would
mean that educational enrichment would cause every individual to get a
higher test score, but would not change the ordering of their
scores.



![Graph of P vs E with two straight parallel lines angled up to the right labeled G1 and G2. G1 is above G2.](figure2.png)

Figure 2. Purely additive interaction
between genotype and environment




In perhaps the most famous paper on this topic the geneticist Richard
Lewontin (1974) argued that actual norms of reaction are likely to be
non-additive (Figure 3). In that case, it makes no sense to talk of a
particular genotype 'determining' a phenotypic difference.
Genotype and environment *jointly* determine the outcome in the
straightforward sense that the effect of each factor on the outcome is
a function of the particular value taken by the other factor. Whether
norms of reaction are typically non-additive and exactly what this
implies is the subject of an extensive scientific and philosophical
literature on 'gene-environment interaction', as discussed
in the previous section.



![Graph of P vs E with two straight lines. G1 goes up to the right, starts below G2, and ends above G2. G2 goes down to the right, starts above G1, and ends below G1.](figure3.png)

Figure 3. Non-additive interaction
between genotype and environment




Kitcher (2001) argues that 'genetic determinism' should be
understood as the claim that many norms of reaction have roughly the
'determinist' shapes depicted in Figures 1 and 2.



In recent philosophical literature on innateness, Sober (1998) is
often credited with the proposal that innateness might be defined as a
flat norm of reaction (but see Cassidy (1979) for an earlier
exposition of this idea). According to Sober:



> 
> ...it is a reasonable hypothesis that the most that can be
> salvaged from the ancient concept of innateness is this: *a
> phenotypic trait is innate for a given genotype if and only if that
> phenotype will emerge in all of a range of developmental
> environments*. What counts as the appropriate range of
> environments is left open in this proposal. Perhaps there is a
> uniquely correct answer to this question; then again, maybe the range
> is determined pragmatically. It is difficult to see how the latter
> conclusion can be evaded. (1998, author's emphasis)
> 



So if the 'ancient' concept of innateness is to be
salvaged in this way, the problem of context sensitivity looms large.
Any given trait is bound to develop in some environmental contexts and
be absent in others. Sober's hope is that this issue can be
solved "pragmatically". This is reminiscent of
Samuels' (2002) suggestion that the question of what counts as a
"normal" environment should be left to scientists and is
not something for philosophers to resolve. Of course, this agnostic
attitude does not make the problem go away. The fact remains that
anyone proposing to define innateness in terms of developmental
stability will have to justify their choice of relevant environments.
The fact that scientists can and do manage to perform quantitative
genetic analyses does not allay the concern that their choice of which
environmental conditions to consider may be arbitrary or
inappropriate.



In his seminal paper 'The idea of innateness' (1975)
Stephen Stich made a similar suggestion, that an innate trait might be
defined as one which an organism will manifest in the
"normal" course of development. But Stich himself offered
a counterexample to this analysis: universally held beliefs, such as
the belief that water quenches thirst, will count as innate on this
analysis, which seems counterintuitive (Stich 1975, 9). Andre
Ariew has offered another counterexample: humans acquire a typical gut
flora during development, but these bacteria are intuitively an
acquired trait rather than an innate trait (Ariew 1999, 133). Ariew
suggests that Stich's analysis confuses evidence for innateness
with innateness itself. Universality is evidence for the existence of
a particular kind of developmental mechanism which Ariew explicates in
terms of Waddington's concept of environmental canalization
(Ariew 2007, 10, and see Section 3.4 below).



Khalidi (2002) identifies a further objection to the proposal that
innateness can be defined as invariance across some
"normal" range of environments. Sometimes, he notes, the
strongest evidenced that a trait is innate is its capacity to develop
in highly *abnormal* conditions. Consider the deprivation
experiments deployed by early ethologists, where animals were raised
in social isolation or other impoverished circumstances. The tendency
for a trait to develop even under these (abnormal) conditions was
regarded as strong evidence of its innateness. From this perspective
it seems utterly wrong-headed to define innateness in terms of some
normal range, so long as "normal" is defined as the
environments which a species typically encounters.



Cowie (1998) pushes on this idea from another direction. Drawing on
Socrates' famous interaction with the slave boy in Plato's
Meno, Cowie notes that the boy's knowledge of geometry is
regarded as innate simply because it developed in an (arguably)
informationally impoverished environment. It makes no difference
whether the slave boy's interaction with Socrates qualifies as a
normal environment or not. Hence, environmental invariance is not
connected, she argues, to intuitive judgments of innateness (see
Khalidi 2002 for a discussion of this argument).


### 3.3 Innateness as environmental canalization



Andre Ariew (1996; 1999; 2007) has developed a more specific
version of the environmental invariance account of innateness.
Following Stich (1975) and Sober (1988), Ariew maintains that the
primary job for the concept of innateness - not just in
psychology, but in the life sciences generally - is to explain
environmental invariance. The problem with the norm of reaction
account, Ariew objects, is that it merely redescribes this pattern
rather than explaining the processes that generate it. In an effort to
explain invariance, Ariew invokes C. H. Waddington's idea of
environmental canalization. An environmentally canalized trait is
buffered against certain types and amounts of environmental variation
over stages of its development. Waddington described this phenomenon
using the metaphor of an "epigenetic landscape" which
consists of a ball rolling down a contoured surface (Figure 4). The
surface is sloped like a pinball machine. The path traced by a ball as
it rolls through a particular valley represents the trajectory of a
developing trait. The amount of "shaking" required to make
the ball jump out of one valley and into another depends on the
overall shape of the landscape. The deeper (more canalized) the
valley, the more buffered the trait is against environmental changes
(or genetic changes, but Ariew focuses on environmental canalization
rather than its complement, genetic canalization). His proposal is
simply that a trait should be considered innate to the extent that it
is environmentally canalized in Waddington's sense. One
advantage of this definition, he adds, is that it represents
innateness as a matter of degree rather than as an all-or-nothing
property.



![figure4a](figure4A.jpg)
  

![figure4b](figure4B.jpg)

Figure 4. Waddington's
developmental landscape (A). Figure B shows the underside of the
landscape with points on the surface anchored to loci in the genome,
representing the idea that genetic mutations will affect the shape of
the landscape. (Waddington 1957, 29 & 36, reproduced with
permission)




Notice that Ariew's proposal hinges on a particular view of
Waddington's metaphor and its cognitive status. Ariew takes this
metaphor to provide a mechanistic explanation of developmental
invariance. This is the purported benefit of Ariew's
canalization account over the invariance proposal. As he explains,
"It is this sense of [environmental] canalization that accounts
for the invariance effect that is central to Sober's account of
biological innateness. But better than a mere invariance account, the
effect is grounded in a real developmental pathway" (Ariew 2007,
579). Linquist (2018) raises doubts about this claim. When we think
carefully about Waddington's landscape metaphor, he argues, it
is difficult to see how it could be regarded as an actual causal
mechanism or even an idealized a model of a mechanism. Instead, most
molecular biologists view canalization as a phenomenon to be explained
rather than as a mechanism that does any explaining. As Greg Gibson
and Gunter Wagner note, "There are likely to be many
molecular mechanisms involved [in canalization], including genetic
redundancy, feedback regulation, and cooperative biochemical
interactions" (2000, 373-74). They go on to state that
"[t]hese are more phenomenological descriptions, however, than
quantitative explanations of buffering." If these more specific
proposals are regarded by developmental biologists as "merely
phenomenological descriptions" and thus fall short of explaining
canalization, where does this leave Waddington's broader and
less specific landscape metaphor? Linquist's (2018) contention
is that any explanatory insight provided by Waddington's
metaphor is merely apparent. Much like the norm of reaction, this
metaphor merely describes the phenomenon of environmental invariance
without explaining it.



Ariew (2007) has proposed a second, very different way in which
canalization might offer an advantage over the invariance account.
Ariew suggests that the concept of canalization provides a framework
for comparing species in their sensitivity to environmental factors.
For example, Sober 1998 introduces three different types of learning
exhibited by different species of songbird. Type 1 songbirds produce
species-typical song even if the bird is reared in silence. Type 2
birds produce species-typical song only after sessions of call and
response with a "tutor" from their own species. Type 3
songbirds produce their species-typical song after encountering any
song at all. These cases are presented by Ariew (2007) as if they vary
along a continuum of sensitivity to environmental cues. Type 1
learning seems the least sensitive. Type 3 learning is only slightly
more sensitive that Type 1, since the trait is "triggered"
by exposure to a wide range of songs. Type 2 learning is the most
sensitive to the specific songs that a bird encounters. Hence,
Ariew's suggestion is that Type 1 is "more innate"
than Type 3, which is in turn "more innate" than Type 2.
By suggesting that birdsong can be organized along a single axis of
innate/triggered/acquired, Ariew seems to be proposing a form of
explanatory unification in the sense developed by Kitcher (1989) (see
the entry on
 Scientific Explanation).
 An important feature of explanatory unification is the capacity to
show how disparate phenomena, previously thought to be unrelated, can
be derived using a single, limited vocabulary for describing them. We
can apply this to Ariew's birdsong example. Upon first
encountering the three types of learning (Types 1, 2, and 3), one
might assume that they are entirely distinct phenomena. However, to
further discover that they vary along a single parameter - i.e.,
the "innateness/triggering/acquired" dimension -
would seem to unify them, in Kitcher's sense.



In response to Ariew's proposal, however, Griffiths and Machery
(2008) argue that canalization is actually a multi-dimensional
phenomenon. There is no such thing as "the" degree to
which a trait is buffered against "the" environment.
Rather, for each trait there are many different environmental factors
capable of influencing its development, each to varying degrees.
Ariew's example with the songbirds seems to work only because it
is oversimplified. With examples of real birds it proves unworkable.
For example, the songs of the much-studied Brown-headed Cowbird are
relatively insensitive to the songs of other male cowbirds. This is in
contrast to the equally well-studied Song Sparrow, whose songs are
highly sensitive to conspecific male songs. So, when we focus on just
this factor - male conspecific song - the cowbirds seem
relatively canalized or "innate" compared to the sparrows.
However, other researchers focus on the ways that courtship
interactions (with females) influence song development. When it comes
to this environmental factor, the song of male cowbirds is much more
sensitive (less canalized) than most sparrows. Hence, song development
will appear more or less canalized or "innate" in these
taxa depending on which environmental factor we focus. Hence,
Griffiths and Machery conclude:



> 
> The strategy of placing traits along a continuum of independence of
> the environment founders on the fact that there is no continuum, but
> rather a high-dimensional space whose axes are often specific to one
> or a few species. Even when the same axes can be applied to different
> species, so that canalization of a character in two species can be
> meaningfully compared, there is no systematic tendency for traits that
> are at the "innate" end of one axis to be at the
> "innate" end of the other. (2008, 402)
> 



This situation threatens Ariew's suggestion that canalization
might serve as a unifying concept in biology and psychology. In order
to effectively unify disparate phenomena, such as the development of
song in different species of birds, a concept must provide some
relatively simple organizing framework. Ariew painted a simplistic
picture of birdsong, giving the impression that different species
could be arranged along a single environmental axis. Griffiths and
Machery object that there are indefinitely many environmental axes
along which a group of species might be compared. Moreover, the
arrangement of species as more or less canalized will vary from one
environmental axis to the next. Such complexity and lack of coherence
makes canalization a bad candidate for conceptual unification.



Griffiths and Machery (2008) mention another consideration that makes
the prospects for conceptual unification seem even less promising.
They note that the kinds of environmental factors that influence trait
development are often highly surprising. For instance, there is a link
between maternal licking of male rat pups and their ability to perform
sexually as adults (Moore 1992). From these examples, one gets the
impression that cryptic environmental influences abound and that the
only obstacle to their discovery is researchers' ability to
anticipate them. However, if researchers are often unaware of which
environmental factors influence a trait, they then are unlikely to
test for those factors experimentally. This means that traits will be
deemed "innate" or environmentally canalized, not because
they are buffered against many environmental factors, but rather
because researchers have not thought to look at the factors to which
they are sensitive.



One way to potentially render scientific statements more accurate is
by demanding that any innateness claim is explicit about the precise
environmental contexts being taken into account. Elizabeth
O'Neil (2014) proposes this as a strategy for revising the
scientific concept of innateness. She proposes that scientists
studying innateness should always explicitly identify the
environmental contexts in which a given trait is (or is not)
developmentally invariant. O'Neill argues that such a shift in
scientific discourse would reduce the amount of confusion produced by
innateness claims. However, even if this new scientific convention
could be established, what further benefit would there be in adding
the term 'innate' after specifying the actual dimensions
and degrees of environmental canalization? Scientists could simply
follow Bateson's call to: "Say what you mean (even if it
uses a bit more space) rather than unintentionally confuse your
readers by employing a word such as innate that carries so many
different connotations" (Bateson 1991, 22).


### 3.4 Other revisionary proposals



We have described three revisionary proposals in detail because they
reflect major themes in the century long controversy about the innate
acquired distinction. But there are many other proposals to redefine
innateness in the philosophical literature.



Ron Mallon and Jonathan Weinberg (2006, 2008) argue that an innate
phenotype is "properly understood" (2008, 415) as one that
is invariant in normal environments (Section 3.2), but also produced
by a 'closed developmental process.' Mallon and
Weinberg's distinction between 'open' and
'closed' processes appears to be the same as that that
drawn by Ernst Mayr (1961) between open and closed genetic programs.
An open developmental process can respond to different environments by
producing a range of different phenotypes, while a closed
developmental process can only produce one or a small number of
outcomes and changing the environment either has no effect or simply
terminates the process, perhaps killing or severely impairing the
organism.



Gualtiero Piccinini and Robert Northcott propose that "traits
are innate to the degree that they are caused by factors intrinsic to
the organism at the time of its origin" (2018, 1). This is the
correct definition of innateness and judgments that disagree with it
should be revised, although they suggest that only those
"untutored" in biology will make such divergent judgments
(2018, 1). Their proposal relies on three key ideas, intrinsic
factors, the organism's moment of origin, and degree of causal
explanation. The idea of intrinsic factors is meant as a superior
alternative to the idea that innate phenotypes depend on genes or on
inherited factors. Those two ideas are replaced by the idea of
"properties that organisms have in virtue of what's within
their boundaries" (2018, 2).  Some of these intrinsic
factors are present at the moment when an organism becomes a new
individual (which they note may not be well-defined for all
organisms). The degree to which these factors explain a phenotype is
to be measured using Northcott's (2013) theory of degrees of
causal explanation.



Nathan Cofnas (2017) has attempted to revive Lorenz's 1965
theory  (See Section 1.4). Lorenz was basically correct that
innate phenotypes are those which are adaptive because of information
contained in the genome, although the details of Lorenz's theory
need revision in light of recent work on epigenetic and cultural
evolution. Cofnas's main addition to Lorenz is to propose that
genes contain adaptive information in the
 'teleosemantic'
 sense that they have evolved by natural selection to create a
particular adaptive match between phenotype and environment.



Muhammad Ali Khalidi (2002; 2007; 2016) has developed an account of
innateness that builds on the older idea of 'poverty of the
stimulus' (Section 1.5). He restricts his account to
psychological traits, where the problems of assessing the relative
weight of genetic and environmental causes can be avoided, "by
focusing on the informational content of the stimulus relative to the
resultant cognitive capacity" (2002, 263). In Khalidi's
view, it is possible to judge the informational complexity of certain
representational states, such as a belief or cognitive skill. It is
also possible, according to Khalidi, to assess the amount of
environmental information available to the organism during
development. The discrepancy between the amount of available
information and the complexity of the belief or skill determines its
degree of innateness. A complex belief that develops in an
informationally impoverished environment is highly innate on this
view. Such beliefs are sometimes described as being
"triggered" by the environment, as opposed to being
learned (Fodor 1981). Hence, Khalidi dubs this the
'triggering' account of innateness: "An innate
cognitive capacity is one that has a disposition or tendency to be
triggered on the basis of an environmental input that is impoverished
by comparison to the resultant cognitive capacity" (Khalidi
2009, 506). Because of its limited range of application this is not
intended as a general  definition of innateness. Rather, the
triggering account is intended as an explication of how cognitive
scientists currently use the term.



It should be clear that the success of this account depends on our
ability to make sense of this notion of informational relevance.
Khalidi admits that a quantitative measure is difficult, but argues
that there are robust non-quantitative ways to document the
informational poverty of the environment relative to the phenotype
(Khalidi 2007).



A consistent theme in recent revisionist proposals is the
authors' conviction that they have correctly diagnosed how
working scientists understand innateness. Cofnas, for example,
suggests that it is primarily philosophers who have criticised the
idea of innateness and that amongst real scientists only "a few
philosophically minded ones" have any reservations about the
concept. To nearly all scientists it is "a valid, useful concept
with an obvious one-sentence definition." (2017, 560) But as we
have described in Section 1, the innate/acquired distinction has been
scientifically controversial ever since Darwin.



There is little cross-citation amongst these recent proposals to
redefine innateness, raising two important issues for future research.
First, are all these analyses extensionally equivalent, classifying
traits as innate or acquired to similar degree? In particular, do they
agree on cases where there has been actual scientific disagreement
about whether the trait is innate, and cases which critics have used
to agree that the distinction is not helpful? Second, and relatedly,
although Khalidi is the only proposal explicitly restricted to one
scientific field, do other analyses implicitly focus on how innateness
is understood in some fields and neglect others?


### 3.5 Eliminativism about the innate/acquired distinction



The previous subsections described attempts to revise the scientific
concept of innateness in order to avoid the semantic confusion that
has obscured the real issues in nearly a century and a half of
controversy about the innate/acquired distinction. To briefly recap,
there are three general problems that critics associate with this
concept. One problem is that the concept is deeply muddled. Mameli and
Bateson (2006) identified as many as 26 distinct
'i-properties' associated with innateness. This alone is a
source of confusion, potentially leading scientists to misunderstand
one another, especially when it comes to communication across
different disciplines. A related worry is that researchers will be
inclined to draw fallacious inferences, where evidence for the
presence of one i-property is taken as sufficient grounds for
inferring the existence of other i-properties. The fact that
psychologists since C.L. Morgan (1896) have warned against this
tendency (see also Dunlap 1919; Bernard 1924; Lehrman 1953; Bateson
1991) indicates that it is a genuine concern among practitioners, and
not merely hypothetical (see Section 2). A second recurring complaint
is that innateness claims draw scientific attention away from the
multifarious and often subtle ways in which environmental factors
contribute to development. Again, this objection has a long history
that extends back to A.R. Wallace (1892) and has been raised on
numerous occasions by psychologists (e.g. Kuo 1921; Lehrman 1970),
biologists (e.g. Hinde 1968; Bateson 1991) and philosophers (e.g.
Cowie 1998; Griffiths 2002). A third objection is that the scientific
concept of innateness is psychologically anchored in an essentialist
folk biology that is scientifically untenable.



Instead of asking scientists to agree to use a revised conception of
innateness, which would then have to be consistently distinguished
from the vernacular conception, a simpler and potentially more
effective strategy is to eliminate the innate/acquired distinction
from scientific discourse. This recommendation has been advocated by a
number of philosophers and some scientists (Mameli and Bateson 2006;
Bateson and Mameli 2007; Griffiths 2002; Griffiths, et al. 2009;
Griffiths and Machery 2008; Linquist et al. 2011; Linquist 2018;
Machery 2017; Machery et al. 2019). This does not mean forbidding the
use of the word 'innate', even if such a thing were
possible or ethical. It merely means reducing its status to that of
phrases like 'in the blood' which are no longer seen as
the names of serious scientific constructs worthy of detailed
investigation.



Cowie (2009) offers a helpful distinction between three types of
eliminativist argument. The first, argues that some type of object or
property fails to exist. She claims that this type of argument cannot
be applied to the concept of innateness because the concept is too
unclear to even specify what it refers to. A second style of argument
claims that a concept should be eliminated because "it
doesn't work." That is, because it is associated with a
failing or degenerate research program. Cowie argues that the concept
of innateness has in fact been highly productive. This is a question
we return to momentarily. The third style of argument claims that the
target concept is so muddled that it should be eliminated for this
reason alone. Cowie (2009) suggests that vagueness and ambiguity can
potentially lead to fruitful research programs. Philosophers should be
cautious about demanding conceptual clarity from scientists when
unclear concepts are leading to productive outcomes.



In support of the suggestion that the concept of innateness has been
scientifically productive, Cowie relies on examples from cognitive
science such as that of Chomsky and his followers on language
acquisition. Although one cannot deny that this concept has been
productive, it is a further question whether certain sciences would
have advanced more rapidly if they had not framed their hypotheses in
terms of the innate/acquired distinction. Another lesson to be drawn
from the history of psychology is that the sheer volume of research
papers on a subject is not always a good indication of a healthy
discipline. The study of instinct was a productive cottage industry at
the beginning of the 20th century (see Section 1.2). Little of this
work is cited today, except as an historical example of a failed
research program. More recently, the discipline of Evolutionary
Psychology has revived a similar approach to nativism as the early
instinct theorists (Hampton 2004). It is controversial whether this
program qualifies as an advance in our understanding of the human mind
(Buller 2006; Laland and Brown 2002). Ultimately, it is an empirical
question whether adherence to an innate/acquired distinction is
conducive to scientific progress. It is notoriously difficult to say
whether a given research program is on the whole more or less
productive than some rival (Laudan 1977). Yet this is an area where,
we think, careful historical and philosophical analysis would pay
valuable dividends.


## 4. Conclusion



The innate/acquired distinction is not only interesting in its own
right, but also serves as an example of how the discipline of
philosophy can and should interact with the scientific fields it
investigates. In this entry we have explored some of the historical
debates over nativism as they have played out within the disciplines
of psychology and biology. Philosophical diagnoses of these debates
tend to focus on particular historical episodes or on the work of
individual historical figures (e.g. Konrad Lorenz and his debate with
Lehrman). This raises an important consideration when evaluating the
generality of a given philosophical diagnosis: to what extent is it
shaped by the particular details of the scientific debate on which it
is based? Our view is that an adequate philosophical diagnosis of what
is at issue in scientific debates over nativism should sample from a
broad range of historical periods and figures.



As we have seen, the word "innate" is used as a technical
term in scientific biology and psychology. It also has a long history
of usage in the vernacular. This dual existence gives rise to two
distinct sets of issues when philosophically analyzing the concept. In
scientific contexts, the core issue is whether some prevailing concept
of innateness adequately serves the epistemic goals of the fields in
which it is employed. It is important to note that epistemic goals can
vary across disciplines, among research programs within a discipline,
and potentially over time. This raises a methodological challenge for
philosophers attempting to evaluate a candidate scientific definition
of innateness. To do the job well, the philosopher must assume the
role of an anthropologist (Dennett 1986) paying careful attention to
the specific ways that scientists are using the term. Some
philosophers have employed the tools of experimental philosophy to aid
in this task. (Griffiths, et al. 2009; Linquist et al. 2011; Knobe and
Samuels 2013; Machery et al. 2019)



An analysis of the vernacular concept raises a distinct set of issues.
The innate/acquired distinction features in socially and ethically
important discussions, for example in disputes about whether human
sexual diversity is 'innate'. Experimental work (Section
3.5) strongly suggests that the vernacular concept of innateness
projects a scientifically discredited essentialism about species onto
nature. This does not seem a sound basis on which to discuss such
issues (Lewens 2020). Arguably, one reason that people continue to
have confidence in the distinction is that they believe there are
scientific experts who are capable of definitively classifying traits
as innate or acquired. But as we have shown in this entry, such
classifications are in reality highly problematic and there is little
agreement either about whether they have scientific value or about how
they should be drawn.