## 1. Introduction



Content is what is said, asserted, thought, believed, desired, hoped
for, etc. Mental content is the content had by mental states and
processes. Causal theories of mental content attempt to explain what
gives thoughts, beliefs, desires, and so forth their contents. They
attempt to explain how thoughts can be about
 things.[1]


## 2. Some Historical and Theoretical Context



Although one might find precursors to causal theories of mental
content scattered throughout the history of philosophy, the current
interest in the topic was spurred, in part, by perceived inadequacies
in "similarity" or "picture" theories of
mental representation. Where meaning and representation are asymmetric
relations--that is, a syntactic item "X" might mean
or represent X, but X does not (typically) mean or represent
"X"--similarity and resemblance are symmetric
relations. Dennis Stampe (1977), who played an important role in
initiating contemporary interest in causal theories, drew attention to
related problems. Consider a photograph of one of two identical twins.
What makes it a photo of Judy, rather than her identical twin Trudy?
By assumption, it cannot be the similarity of the photo to one twin
rather than the other, since the twins are identical. Moreover, one
can have a photo of Judy even though the photo happens not to look
very much like her at all. What apparently makes a photo of Judy a
photo of Judy is that she was causally implicated, in the right way,
in the production of the photo. Reinforcing the hunch that causation
could be relevant to meaning and representation is the observation
that there is a sense in which the number of rings in a tree stump
represents the age of the tree when it died and that the presence of
smoke means fire. The history of contemporary developments of causal
theories of mental content consists largely of specifying what it is
for something to be causally implicated in the right way in the
production of meaning and refining the sense in which smoke represents
fire to the sense in which a person's thoughts, sometimes at
least, represent the world.



If one wanted to trace a simple historical arc for recent causal
theories, one would have to begin with the seminal 1977 paper by
Dennis Stampe, "Toward a Causal Theory of Linguistic
Representation." Among the many important features of this paper
is its having set much of the conceptual and theoretical stage to be
described in greater detail below. It drew a contrast between causal
theories and "picture theories" that try to explain
representational content by appeal to some form of similarity between
a representation and the thing represented. It also drew attention to
the problem of distinguishing the content determining causes of a
representation from adventitious non-content determining causes. So,
for example, one will want "X" to mean dogs because dogs
causes dogs, but one does not want "X" to mean
blow-to-the-head, even though blows to the head might cause the
occurrence of an "X". (Much more of this will be described
below.) Finally, it also provided some attempts to address this
problem, such as an appeal to the function a thing might have.



Fred Dretske's 1981 *Knowledge and the Flow of
Information* offered a much expanded treatment of a type of causal
theory. Rather than basing semantic content on a causal connection
*per se*, Dretske began with a type of informational connection
derived from the mathematical theory of information. This has led some
to refer to Dretske's theory as "information
semantics". Dretske also appealed to the notion of function in
an attempt to distinguish content determining causes from adventitious
non-content determining causes. This has led some to refer to
Dretske's theory as a "teleoinformational" theory or
a "teleosemantic" theory. Dretske's 1988 book,
*Explaining Behavior*, further refined his earlier
treatment.



Jerry Fodor's 1984 "Semantics, Wisconsin Style" gave
the problem of distinguishing content-determining causes from
non-content determining causes its best-known guise as "the
disjunction problem". How can a causal theory of content say
that "X" has the non-disjunctive content dog, rather than
the disjunctive content dog-or-blow-to-the-head, when both dogs and
blows to the head cause instances of "X"? By 1987, in
*Psychosemantics*, Fodor published his first attempt at an
alternative method of solving the disjunction problem, the Asymmetric
(Causal) Dependency Theory. This theory was further refined for the
title essay in Fodor's 1990 book *A Theory of Content and
Other Essays*.



Although these causal theories have subsequently spawned a significant
critical literature, other related causal theories have also been
advanced. Two of these are teleosemantic theories that are sometimes
contrasted with causal theories. (Cf., e.g., Papineau (1984), Millikan
(1989), and the entry on 
 teleological theories of mental content.) 
Other more purely causal theories are Dan Lloyd's (1987, 1989)
Dialectical Theory of Representation, Robert Rupert's (1999)
Best Test Theory (see section 3.5 below), Marius Usher's (2001)
Statistical Referential Theory, and Dan Ryder's (2004) SINBAD
neurosemantics.



Causal theories of mental content are typically developed in the
context of four principal assumptions. First, they typically
presuppose that there is a difference between derived and underived
 meaning.[2]
 Normal humans can use one thing, such as "%", to mean
percent. They can use certain large red octagons to mean that one is
to stop at an intersection. In such cases, there are collective
arrangements that confer relatively specific meanings on relatively
specific objects. In the case of human minds, however, it is proposed
that thoughts can have the meanings or contents they do without
recourse to collective arrangements. It is possible to think about
percentage or ways of negotiating intersections prior to collective
social arrangements. It, therefore, appears that the contents of our
thoughts do not acquire the content they do in the way that
"%" and certain large red octagons do. Causal theories of
mental content presuppose that mental contents are underived, hence
attempt to explain how underived meaning arises.



Second, causal theories of mental content distinguish what has come to
be known as *natural meaning* and *non-natural
 meaning*.[3]
 Cases where an object or event X has natural meaning are those in
which, given certain background conditions, the existence or
occurrence of X "entails" the existence or occurrence of
some state of affairs. If smoke in the unspoiled forest naturally
means fire then, given the presence of smoke, there was fire. Under
the relevant background conditions, the effect indicates or naturally
means the cause. An important feature of natural meaning is that it
does not generate falsity. If smoke naturally means fire, then there
must really be a fire. By contrast, many non-naturally meaningful
things can be false. Sentences, for example, can be meaningful and
false. The utterance "Colleen currently has measles" means
that Colleen currently has measles but does not entail that Colleen
currently has measles in the way that Colleen's spots do entail
that she has measles. Like sentences, thoughts are also meaningful,
but often false. Thus, it is generally supposed that mental content
must be a form of *non-natural* underived
 meaning.[4]



Third, these theories assume that it is possible to explain the origin
of underived content without appeal to other semantic or contentful
notions. So, it is assumed that there is more to the project than
simply saying that one's thoughts mean that Colleen currently
has the measles because one's thoughts are about Colleen
currently having the measles. Explicating meaning in terms of
aboutness, or aboutness in terms of meaning, or either in terms of
some still further semantic notion, does not go as far as is commonly
desired by those who develop causal theories of mental content. To
note some additional terminology, it is often said that causal
theories of mental content attempt to *naturalize* non-natural,
underived meaning. To put the matter less technically, one might say
that causal theories of mental content presuppose that it is possible
for a purely physical system to bear underived content. Thus, they
presuppose that if one were to build a genuinely thinking robot or
computer, one would have to design it in such a way that some of its
internal components would bear non-natural, underived content in
virtue of purely physical conditions. To get a feel for the difference
between a naturalized theory and an unnaturalized theory of content,
one might note the theory developed by Grice (1948). Grice developed
an unnaturalized theory. Speaking of linguistic items, Grice held that
'Speaker S non-naturally means something by
"X"' is roughly equivalent to 'S intended the
utterance of "X" to produce some effect in an audience by
means of the recognition of this intention.' Grice did not
explicate the origin of mental content of speaker's intentions
or audience recognition, hence he did not attempt to naturalize the
meaning of linguistic items.



Fourth, it is commonly presupposed that naturalistic analyses of
non-natural, underived meanings will apply, in the first instance,
to the contents of thought. The physical items "X" that
are supposed to be bearers of causally determined content will,
therefore, be something like the firings of a particular neuron or set
of neurons. These contents of thoughts are said to be captured in what
is sometimes called a "language of thought" or
"mentalese." The contents of items in natural languages,
such as English, Japanese, and French, will then be given a separate
analysis, presumably in terms of a naturalistic account of non-natural
derived meanings. It is, of course, possible to suppose that it is
natural language, or some other system of communication, that first
develops content, which can then serve as a basis upon which to
provide an account of mental content. Among the reasons that threaten
this order of dependency is the fact that cognitive agents appear to
have evolved before systems of communication. Another reason is that
human infants at least appear to have some sophisticated cognitive
capacities involving mental representation, before they speak or
understand natural languages. Yet another reason is that, although
some social animals may have systems of communication complex enough
to support the genesis of mental content, other non-social cognizing
animals may not.



It is worth noting that, in recent years, this last presupposition has
sometimes been abandoned by philosophers attempting to understand
animal signaling or animal communication, as when toads emit mating
calls or vervet monkeys cry out when seeing a cheetah, eagle, or
snake. See, for example, Stegmann, 2005, 2009, Skyrms, 2008, 2010a, b,
2012, and Birch, 2014. In other words, there have been efforts to use
the sorts of apparatus originally developed for theories of mental
content, plus or minus a bit, as apparatus for handling animal
signaling. These approaches seem to allow that there are mental
representations in the brains of the signaling/communicating animals,
but do not reply on the content of the mental representations to
provide the representational contents of the signals. In this way, the
contents of the signals are not derived from the contents of the
mental representations.


## 3. Specific Causal Theories of Mental Content



The unifying inspiration for causal theories of mental content is that
some syntactic item "X" means X because "X"s
are caused by
 Xs.[5]
 Matters cannot be this simple, however, since in general one expects
that some causes of "X" are not among the
content-specifying causes of "X"s. There are numerous
examples illustrating this point, each illustrating a kind of cause
that must not typically be among the content-determining causes of
"X":


1. Suppose there is some syntactic item "X" that is a
putative mental representation of a dog. Dogs will presumably cause
tokens of "X", but so might foxes at odd angles, with some
obstructions, at a distance, or under poor lighting conditions. The
causal theorist will need some principle that allows her to say that
the causal links between dogs and "X"s will be
content-determining, where the causal links between, say, foxes and
"X"s will not. Mice and shrews, mules and donkeys, German
Shepherds and wolves, dogs and paper mache dogs, dogs and
stuffed dogs, and any number of confusable groups would do to make
this point.
2. A syntactic item "X" with the putative content of dog
might also be caused by a dose of LSD, a set of strategically placed
and activated microelectrodes, a brain tumor, or quantum mechanical
fluctuations. Who knows what mental representations might be triggered
by these things? LSD, microelectrodes, etc., should (typically) not be
among the content-determining causes of most mental
representations.
3. Upon hearing the question "What kind of animal is named
'Fido'?" a person might token the syntactic item
"X". One will want at least some cases in which this
"X" means dog, but to get this result the causal theorist
will not want the question to be among the content-determining causes
of "X".
4. In seeing a dog, there is a causal pathway between the dog through
the visual system (and perhaps beyond) to a token of "X".
What in this causal pathway from the dog to "X"
constitutes the content-determining element? In virtue of what is it
the case that "X" means dog, rather than retinal
projection of a dog, or any number of other possible points along the
pathway? Clearly there is a similar problem for other sense
modalities. In hearing a dog, there is a causal pathway between the
dog through the auditory system (and perhaps beyond) to a token of
"X". What makes "X" mean dog, rather than
sound of a dog (barking?) or eardrum vibration or motion in the stapes
bone of the inner ear? One might press essentially the same point by
asking what makes "X" mean dog, rather than some complex
function of all the diverse causal intermediaries between dogs and
"X".



The foregoing problem cases are generally developed under the rubric
of "false beliefs" or "the disjunction
problem" in the following way and can be traced to Fodor (1984).
No one is perfect, so a theory of content should be able to explicate
what is going on when a person makes a mistake, such as mistaking a
fox for a dog. The first thought is that this happens when a fox (at a
distance or in poor lighting conditions) causes the occurrence of a
token of "X" and, since "X" means dog, one has
mistaken a fox for a dog. The problem with this first thought arises
with the invocation of the idea that "X" means dog. Why
say that "X" means dog, rather than dog or fox? On a
causal account, we need some principled reason to say that the content
of "X" is dog, hence that the token of "X" is
falsely tokened by the fox, rather than the content of "X"
is dog or fox, hence that the token of "X" is truly
tokened by the fox. What basis is there for saying that
"X" means dog, rather than dog or fox? Because there
appears always to be this option of making the content of a term some
disjunction of items, the problem has been called "the
disjunction
 problem".[6]



As was noted above, what unifies causal theories of mental content is
some version of the idea that "X"s being causally
connected to Xs makes "X"s mean Xs. What divides causal
theories of mental content, most notably, is the different approaches
they take to separating the content-determining causes from the
non-content-determining causes. Some of these different theories
appeal to normal conditions, others to functions generated by natural
selection, others to functions acquired ontogenetically, and still
others to dependencies among laws. At present there is no approach
that is commonly agreed to correctly separate the content-determining
causes from the non-content determining causes while at the same time
respecting the need not to invoke existing semantic concepts. Although
each attempt may have technical problems of its own, the recurring
problem is that the attempts to separate content-determining from
non-content-determining causes threaten to smuggle in semantic
elements.



In this section, we will review the internal problematic of causal
theories by examining how each theory fares on our battery of test
cases (I)-(IV), along with other objections from time to time.
This provides a simple, readily understood organization of the project
of developing a causal theory of mental content, but it does this at a
price. The primary literature is not arranged exactly in this way. The
positive theories found in the primary literature are typically more
nuanced than what we present here. Moreover, the criticisms are not
arranged into the kind of test battery we have with cases
(I)-(IV). One paper might bring forward cases (I) and (III)
against theory A, where another paper might bring forward cases (I)
and (II) against theory B. Nor are the examples in our test battery
exactly the ones developed in the primary literature. In other words,
the price one pays for this simplicity of organization is that we have
something less like a literature review and more like a theoretical
and conceptual toolbox for understanding causal theories.


### 3.1 Normal Conditions



Trees usually grow a certain way. Each year, there is the passage of
the four seasons with a tree growing more quickly at some times and
more slowly at others. As a result, each year a tree adds a
"ring" to its girth in such a way that one might say that
each ring means a year of growth. If we find a tree stump that has
twelve rings, then that means that the tree was twelve years old when
it died. But, it is not an entirely inviolable law that a tree grows a
ring each year. Such a law, if it is one, is at most a *ceteris
paribus* law. It holds only given certain background conditions,
such as that weather conditions are normal. If the weather conditions
are especially bad one season, then perhaps the tree will not grow
enough to produce a new ring. One might, therefore, propose that if
conditions are normal, then n rings means that the tree was n years
old when it died. This idea makes its first appearance when Stampe
(1977) invokes it as part of his theory of "fidelity
conditions."



An appeal to normal conditions would seem to be an obvious way in
which to bracket at least some non-content-determining causes of a
would-be mental representation "X". It is only the causes
that operate under normal conditions that are content-determining. So,
when it comes to human brains, under normal conditions one is not
under the influence of hallucinogens nor is one's head being
invaded by an elaborate configuration of microelectrodes. So, even
though LSD and microelectrodes would, counterfactually speaking, cause
a token neural event "X", these causes would not be among
the content-determining causes of "X". Moreover, one can
take normal conditions of viewing to include good lighting, a
particular perspective, a particular viewing distance, a lack of
(seriously) occluding objects, and so forth, so that foxes in dim
light, viewed from the bottom up, at a remove of a mile, or through a
dense fog, would not be among the content-determining causes of
"X". Under normal viewing conditions, one does not confuse
a fox with a dog, so foxes are not to be counted as part of the
content of "X". Moreover, if one does confuse a fox with a
dog under normal viewing conditions, then perhaps one does not really
have a mental representation of a dog, but maybe only a mental
representation of a member of the taxonomic family canidae.



Although an appeal to normal conditions initially appears promising,
it does not seem to be sufficient to rule out the causal
intermediaries between objects in the environment and "X".
Even under normal conditions of viewing that include good lighting, a
particular perspective, a particular viewing distance, a lack of
(seriously) occluding objects, and so forth, it is still the case that
both dogs and, say, retinal projections of dogs, lead to tokens of
"X". Why does the content of "X" not include
retinal projections of dogs or any of the other causal intermediaries?
Nor do normal conditions suffice to keep questions from getting in
among the content-determining causes. What abnormal conditions are
there when the question, "What kind of animal is named
'Fido'?," leads to a tokening of an "X"
with the putative meaning of dog? Suppose there are instances of
quantum mechanical fluctuations in the nervous system, wherein
spontaneous changes in neurons lead to tokens of "X". Do
normal conditions block these out? So, there are problem cases in
which appeals to normal conditions do not seem to work. Fodor (1990b)
discusses this problem with proximal stimulations in connection with
his asymmetric dependency theory, but it is one that clearly
challenges the causal theory plus normal conditions approach.



Next, suppose that we tightly construe normal conditions to eliminate
the kinds of problem cases described above. So, when completely
fleshed out, under normal conditions only dogs cause "X"s.
What one intuitively wants is to be able to say that, under normal
conditions of good lighting, proper viewing distance, etc.
"X" means dog. But, another possibility is that in such a
situation "X" does not mean dog, but
dog-under-normal-conditions-of-good-lighting, proper-viewing-distance,
etc. Why take one interpretation over another? One needs a principled
basis for distinguishing *the* cause of "X" from
the many causally contributing factors. In other words, we still have
the problem of bracketing non-content-determining causes, only in a
slightly reformulated manner. This sort of objection may be found in
Fodor (1984).



Now set the preceding problem aside. There is still another developed
in Fodor (1984). Suppose that "X" does mean dog under
conditions of good lighting, lack of serious occlusions, etc. Do not
merely suppose that "X" is caused by dogs under conditions
of good light, lack of serious occlusions, etc.; grant that
"X" really does mean dog under these conditions. Even
then, why does "X", the firing of the neuronal circuit,
still mean dog, when those conditions do not hold? Why does
"X" still mean dog under, say, degraded lighting
conditions? After all, we could abide by another apparently true
conditional regarding these other conditions, namely, if the lighting
conditions were not so good, there were no serious occlusions, etc.,
then the neuronal circuit's firing would mean dog or fox. Even
if "X" means X under one set of conditions C1,
why doesn't "X" mean Y under a different set of
conditions C2? It looks as though one could say that
C1 provides normal conditions under which "X"
means X and C2 provides normal conditions under which
"X" means Y. We need some non-semantic notions to enable
us to fix on one interpretation, rather than the other. At this point,
one might look to a notion of functions to solve these
 problems.[7]


### 3.2 Evolutionary Functions



Many physical objects have functions. (Stampe (1977) was the first to
note this as a fact that might help causal theories of content.) A
familiar mercury thermometer has the function of indicating
temperature. But, such a thermometer works against a set of background
conditions which include the atmospheric pressure. The atmospheric
pressure influences the volume of the vacuum that forms above the
column of mercury in the glass tube. So, the height of the column of
mercury is the product of two causally relevant features, the ambient
atmospheric temperature and the ambient atmospheric pressure. This
suggests that one and the same physical device with the same causal
dependencies can be used in different ways. A column of mercury in a
glass tube can be used to measure temperature, but it is possible to
put it to use as a pressure gauge. Which thing a column of mercury
measures is determined by its function.



This observation suggests a way to specify which causes of
"X" determine its content. The content of "X",
say, the firing of some neurons, is determined by dogs, and not foxes,
because it is the function of those neurons to register the presence
of dogs, but not foxes. Further, the content of "X" does
not include LSD, microelectrodes, or quantum mechanical fluctuations,
because it is not the function of "X" to fire in response
to LSD, microelectrodes, or quantum mechanical fluctuations in the
brain. Similarly, the content of "X" does not include
proximal sensory projections of dogs, because the function of the
neurons is to register the presence of the dogs, not the sensory
stimulations. It is the objective features of the world that matter to
an organism, not its sensory states. Finally, it is the function of
"X" to register the presence of dogs, but not the presence
of questions, such as 'What kind of animal is named 
"Fido"?',
that leads to "X" meaning dogs. Functions, thus, provide
a *prima facie* attractive means of properly winnowing down the
causes of "X" to those that are genuinely content
determining.



In addition, the theory of evolution by natural selection apparently
provides a non-semantic, non-intentional basis upon which to explicate
functions and, in turn, semantic content. Individual organisms vary in
their characteristics, such as how their neurons respond to features
of the environment. Some of these differences in how neurons respond
make a difference to an organism's survival and reproduction.
Finally, some of these very differences may be heritable. Natural
selection, commonly understood as this differential reproduction of
heritable variation, is purely causal. Suppose that there is a
population of rabbits. Further suppose that either by a genetic
mutation or by the recombination of existing genes, some of these
rabbits develop neurons that are wired into their visual systems in
such a way that they fire (more or less reliably) in the presence of
dogs. Further, the firing of these neurons is wired into a freezing
behavior in these rabbits. Because of this configuration, the rabbits
with the "dog neurons" are less likely to be detected by
dogs, hence more likely to survive and reproduce. Finally, because the
genes for these neurons are heritable, the offspring of these
dog-sensitive rabbits will themselves be dog-sensitive. Over time, the
number of the dog-sensitive rabbits will increase, thereby displacing
the dog-insensitive rabbits. So, natural selection will, in such a
scenario, give rise to mental representations of dogs. Insofar as such
a story is plausible, there is hope that natural selection and the
genesis of functions can provide a naturalistically acceptable means
of delimiting content-determining causes.


#### 3.2.1 Objections to Evolutionary Functions



There is no doubt that individual variation, differential
reproduction, and inheritance can be understood in a purely causal
manner. Yet, there remains skepticism about how naturalistically one
can describe what natural selection can select for. There are doubts
about the extent to which the objects of selection really can be
specified without illicit importation of intentional notions. Fodor
(1989, 1990a) give voice to some of this skepticism. *Prima
facie*, it makes sense to say that the neurons in our hypothetical
rabbits fire in response to the presence of dogs, hence that there is
selection for dog representations. But, it makes just as much sense,
one might worry, to say that it is sensitivity to dog-look-alikes that
leads to the greater fitness of the rabbits with the new
 neurons.[8]
 There are genes for the dog-look-alike neurons and these genes are
heritable. Moreover, those rabbits that freeze in response to
dog-look-alikes are more likely to survive and reproduce than are
those that do not so freeze, hence one might say that the freezing is
in response to dog-look-alikes. So, our ability to say that the
meaning of the rabbits' mental representation "X" is
dog, rather than dog-look-alike, depends on our ability to say that it
is the dog-sensitivity of "X", rather than the
dog-look-alike-sensitivity of "X", that keeps the rabbits
alive longer. Of course, being dog-sensitive and being
dog-look-alike-sensitive are connected, but the problem here is that
both being dog-look-alike-sensitive and being dog-sensitive can
increase fitness in ways that lead to the fixation of a genotype. And
it can well be that it is avoidance of dogs that keeps a rabbit alive,
but one still needs some principled basis for saying that the rabbits
avoid dogs by being sensitive to dogs, rather than by being sensitive
to dog-look-alikes. The latter appears to be good enough for the
differential reproduction of heritable variation to do its work. Where
we risk importing semantic notions into the mix is in understanding
selection intentionally, rather than purely causally. We need a notion
of "selection for" that is both general enough to work for
all the mental contents causal theorists aspire to address and that
does not tacitly import semantic notions.



In response to this sort of objection, it has been proposed that the
correct explanation of a rabbit's evolutionary success with,
say, "X", is not that this enables the rabbit to avoid
dog-look-alikes, but that it enables them to avoid dogs. It is dogs,
but not mere dog-look-alikes, that prey on rabbits. (This sort of
response is developed in Millikan (1991) and Neander (1995).) Yet, the
rejoinder is that if we really want to get at the correct explanation
of a rabbit-cum-"X" system, then we should not suppose
that "X" means dog. Instead, we should say that it is in
virtue of the fact that "X" picks up on something like,
say, predator of such and such characteristics that the
"X" alarm system increases the chance of a rabbit's
survival. (This sort of rejoinder may be found in Agar (1993).)



This problem aside, there is also some concern about the extent to
which it is plausible to suppose that natural selection could act on
the fine details of the operation of the brain, such as the firing of
neurons in the presence of dogs. (This is an objection raised in Fodor
(1990c)). Natural selection might operate to increase the size of the
brain so there is more cortical mass for cognitive processing. Natural
selection might also operate to increase the folding of the brain so
as to maximize the cortical surface area that can be contained within
the brain. Natural selection might also lead to compartmentalization
of the brain, so that one particular region could be dedicated to
visual processing, another to auditory processing, and still another
to face processing. Yet, many would take it to be implausible to
suppose that natural selection works at the level of individual mental
representations. The brain is too plastic and there is too much
individual variation in the brains of mammals to admit of selection
acting in this way. Moreover, such far reaching effects of natural
selection would lead to innate ideas not merely of colors and shapes,
but of dogs, cats, cars, skyscrapers, and movie stars. Rather than
supposing that functions are determined by natural selection across
multiple generations, many philosophers contend that it is more
plausible that the functions that underlie mental representations are
acquired through cognitive development.


### 3.3 Developmental Functions



Hypothesizing that certain activities or events within the brain mean
what they do, in part, because of some function that develops over the
course of an individual's lifetime shares many of the attractive
features of the hypothesis that these same activities or events mean
what they do, in part, because of some evolutionarily acquired
function. One again can say that it is not the function of
"X" to register the presence of LSD, microelectrodes,
foxes, stuffed dogs, or paper mache dogs, or questions,
but it is their function to report on dogs. Moreover, it does not
invoke dubious suppositions about an intimate connection between
natural selection and the precise details of neuronal hardware and its
operation. A functional account based on ontogenetic function
acquisition or learning seems to be an improvement. This is the core
of the approach taken in Dretske (1981; 1988).



The function acquisition story proposes that during development, an
organism is trained to discriminate real flesh and blood dogs from
questions, foxes, stuffed dogs, paper mache dogs under
conditions of good lighting, without occlusions, or distractions. A
teacher ensures that training proceeds according to plan. Once
"X" has acquired the function to respond to dogs, the
training is over. Thereafter, any instances in which "X"
is triggered by foxes, stuffed dogs, paper mache dogs,
LSD, microelectrodes, etc., are false tokenings and figure into false
beliefs.


#### 3.3.1 Objections to Developmental Functions



Among the most familiar objections to this proposal is that there is
no principled distinction between when a creature is learning and when
it is done learning. Instances in which a creature entertains the
hypothesis that "X" means X, instances in which the
creature entertains the hypothesis that "X" means Y,
instances in which the creature straightforwardly uses "X"
to mean X, and instances in which the creature straightforwardly uses
"X" to mean Y are thoroughly intermingled. The problem is
perhaps more clearly illustrated with tokens of natural language,
where children will use words struggling through correct and incorrect
uses of a word before (perhaps) finally settling on a correct usage.
There seems to be no principled way to specify if learning has stopped
or whether there is instead "lifelong learning". This is
among the objections to be found in Fodor (1984).



This, however, is a relatively technical objection. Further reflection
suggests that there may be an underlying appeal to the intentions of
the teacher. Let us revisit the learning story. Suppose that during
the learning period the subject is trained to use "X" as a
mental representation of dogs. Now, let the student graduate from
"X" using school and immediately thereafter see a fox.
Seeing this fox causes a token of "X" and one would like
to say that this is an instance of mistaking a fox for a dog, hence a
false tokening. But, consider the situation counterfactually. If the
student had seen the fox during the training period just before
graduation, the fox would have triggered a token of "X".
This suggests that we might just as well say that the student learned
that "X" means fox or dog as that the student learned that
"X" means dog. Thus, we might just as well say that, after
training, the graduate does not falsely think of a dog, but truly
thinks of a fox or a dog. The threat of running afoul of naturalist
scruples comes if one attempts to say, in one way or another, that it
is because the teacher *meant* for the student to learn that
"X" means dog, rather than "X" means fox or
dog. The threatened violation of naturalism comes in invoking the
teacher's intentions. This, too, is an objection to be found in
Fodor (1984).


### 3.4 Asymmetric Dependency Theory



The preceding attempts to distinguish the content-determining causes
from non-content-determining causes focused on the background or
boundary conditions under which the distinct types of causes may be
thought to act. Fodor's Asymmetric Dependency Theory (ADT),
however, represents a bold alternative to these approaches. Although
Fodor (1987, 1990a, b, 1994) contain numerous variations on the
details of the theory, the core idea is that the content-determining
cause is in an important sense fundamental, where the
non-content-determining causes are non-fundamental. The sense of being
fundamental is that the non-content-determining causes depend on the
content-determining cause; the non-content-determining causes would
not exist if not for the content-determining cause. Put a bit more
technically, there are numerous laws such as 'Y1
causes "X",' 'Y2 causes
"X",' etc., but none of these laws would exist were
it not a law that X causes "X". The fact that the 'X
causes "X"' law does not in the same way depend on
any of the Y1, Y2, ..., Yn laws
makes the dependence asymmetric. Hence, there is an asymmetric
dependency between the laws. The intuition here is that the question,
'What kind of animal is called "Fido"?' will
cause an occurrence of the representation "X" only because
of the fact that dogs cause "X". Instances of foxes cause
instances of "X" only because foxes are mistaken for dogs
and dogs cause instances of "X".



Causation is typically understood to have a temporal dimension. First
there is event C and this event C subsequently leads to event E. Thus,
when the ADT is sometimes referred to as the "Asymmetric Causal
Dependency Theory," the term "causal" might suggest
a diachronic picture in which there is, first, an X-"X"
law which subsequently gives rise to the various Y-"X"
laws. Such a diachronic interpretation, however, would lead to
counterexamples for the ADT approach. Fodor (1987) discusses this
possibility. Consider Pavlovian conditioning. Food causes salivation
in a dog. Then a bell causes salivation in the dog. It is likely that
the bell causes salivation only because the food causes it. Yet,
salivation hardly means food. It may well naturally mean that food is
present, but salivation is not a thought or thought content and it is
not ripe for false semantic tokening. Or take a more exotic kind of
case. Suppose that one comes to apply "X" to dogs, but
only by means of observations of foxes. This would be a weird case of
"learning", but if things were to go this way, one would
not want "X" to mean fox. To block this kind of objection,
the theory maintains the dependency between the fundamental
X-"X" law and the non-fundamental Y-"X" laws
is synchronic. The dependency is such that if one were to break the
X-"X" law at time t, then one would thereby
instantaneously break all the Y-"X" laws at that time.



The core of ADT, therefore, comes down to this. "X" means
X if


1. 'Xs cause "X"s' is a law,
2. For all Ys that are not Xs, if Ys qua Ys actually cause
"X"s, then the Y's causing "X"s is
asymmetrically dependent on the Xs causing "X"s,
3. The dependence in (2) is *synchronic* (not
diachronic).



This seems to get a number of cases right. The reason that questions
like "What kind of animal is named 'Fido'?" or
"What is a Sheltie?" trigger "X", meaning dog,
is that dogs are able to trigger "X"s. Foxes only trigger
"X"s, meaning dog, because dogs are able to trigger them.
Moreover, it appears to solve the disjunction problem. Suppose we have
a 'dogs cause "X"s' law and a 'dogs or
foxes cause "X"s' law. If one breaks the 'dogs
cause "X"s' law, then one thereby breaks the
'dogs or foxes cause "X"s' law, since the only
reason either dogs or foxes cause "X"s is because dogs do.
Moreover, if one breaks the 'dogs or foxes cause
"X"s' law, one does not thereby break the
'dogs cause "X"s' law, since dogs alone might
suffice to cause "X"s. So, the 'dogs or foxes cause
"X"s' law depends on the 'dogs cause
"X"s' law, but not vice versa. Asymmetric dependency
of laws gives the right
 results.[9]


#### 3.4.1 Objections to ADT



Adams and Aizawa (1994) mention an important class of causes that the
ADT does not appear to handle, namely, the "non-psychological
interventions". We have all along assumed the "X" is
some sort of brain event, such as the firing of some neurons. But, it
is plausible that some interventions, such as a dose of hallucinogen
or maybe some carefully placed microelectrodes, could trigger such
brain events, quite apart from the connection of those brain events to
other events in the external world. If essentially all brain events
are so artificially inducible, then it would appear that for all
putative mental representations, there will be some laws, such as
'microelectrodes cause "X"s,' that do not
depend on laws such as 'dogs causes "X"s.' If
this is the case, then the second condition of the ADT would rarely or
never be satisfied, so that the theory would have little relevance to
actual cognitive scientific practice.



Fodor (1990a) discusses challenges that arise with the fact that the
perception of objects involves causal intermediaries. Suppose that
there is a dog-"X" law that is mediated entirely by
sensory mechanisms. In fact, suppose unrealistically that the
dog-"X" law is mediated by a single visual sensory
projection. In other words let the dog-"X" law be mediated
by the combination of a dog-dogsp law and a
dogsp-"X" law. Under these conditions, it
appears that "X" means dogsp, rather than dog.
Condition (1) is satisfied, since there is a
dogsp-"X" law. Condition (2) is satisfied,
since if one were to break the dogsp-"X" law
one would thereby break the dog-"X" law (i.e., there is a
dependence of one law one the other) and breaking the
dog-"X" law would not necessarily break the
dogsp-"X" law (i.e., the dependence is not
symmetric). The dependence is asymmetric, because one can break the
dog-"X" law by breaking the dog-dogsp law (by
changing the way dogs look) without thereby breaking the
dogsp-"X" law. Finally, condition (3) is
satisfied, since the dependence of the dog-"X" law on the
dogsp-"X" law is synchronic.



The foregoing version of the sensory projections problem relies on
what was noted to be the unrealistic assumption that the
dog-"X" law is mediated by a single visual sensory
projection. Relaxing the assumption does not so much solve the problem
as transform it. So, adopt the more realistic assumption that the
dog-"X" law is sustained by a combination of a large set
of dog-sensory projection laws and a large set of
dogsp-"X" laws. In the first set, we have laws
connecting dogs to particular patterns of retinal stimulation, laws
connecting dogs to particular patterns of acoustic stimulation, etc.
In the second set, we have certain psychological laws connecting
particular patterns of retinal stimulation to "X", certain
psychological laws connecting particular patterns of acoustic
stimulation to "X", etc. In this sort of situation, there
threatens to be no "fundamental" law, no law on which all
other laws asymmetrically depend. If one breaks the
dog-"X" law one does not thereby break any of the sensory
projection-"X" laws, since the former can be broken by
dissolving all of the dog-sensory projection laws. If, however, one
breaks any one of the particular dogsp-"X"
laws, e.g. one connecting a particular doggish visual appearance to
"X", one does not thereby break the dog-"X"
law. The other sensory projections might sustain the
dog-"X" law. Moreover, breaking the law connecting a
particular doggish look to "X" will not thereby break a
law connecting a particular doggish sound to "X". Without
a "fundamental" law, there is no meaning in virtue of the
conditions of the ADT. Further, the applicability of the ADT appears
to be dramatically reduced insofar as connections between mental
representations and properties in the world are mediated by sensory
projections. (See Neander, 2013, Schulte, 2018, Artiga &
Sebastian, 2020, for discussion of the distality problem for
other causal theories.)



Another problem arises with items or kinds that are indistinguishable.
Adams and Aizawa (1994), and, implicitly, McLaughlin, (1991), among
others, have discussed this problem. As one example, consider the time
at which the two minerals, jadeite and nephrite, were chemically
indistinguishable and were both thought to be jade. As another, one
might appeal to H2O and XYZ (the stuff of philosophical
thought experiments, the water look-alike substance found on
twin-earth). Let X = jadeite and Y = nephrite and let there be laws
'jadeite causes "X"' and 'nephrite
causes "X"'. Can "X" mean jadeite? No.
Condition (1) is satisfied, since it is a law that 'jadeite
causes "X"'. Condition (3) is satisfied, since
breaking the jadeite-"X" law will immediately break the
nephrite-"X" law. If jadeite cannot trigger an
"X", then neither can nephrite, since the two are
indistinguishable. That is, there is a synchronic dependence of the
'nephrite causes "X"' law on the
'jadeite causes "X" law. The problem arises with
condition (2). Breaking the jadeite-"X" law will thereby
break the nephrite-"X" law, but breaking the
nephrite-"X" law will also thereby break the
jadeite-"X" law. Condition (2) cannot be satisfied, since
there is a symmetric dependence between the jadeite-"X"
law and the nephrite-"X" law. By parity of reasoning,
"X" cannot mean nephrite. So, can "X" mean
jade? No. As before, conditions (1) and (3) could be satisfied, since
there could be a jade-"X" law and the
jadeite-"X" law and the nephrite-"X" law could
synchronically depend on it. The problem is, again, with condition
(2). Presumably breaking the jade-"X" law would break the
jadeite-"X" and nephrite-"X" law, but breaking
either of them would break the jade-"X" law. The problem
is, again, with symmetric dependencies.



Here is a problem that we earlier found in conjunction with other
causal theories. Despite the bold new idea underlying the ADT method
of partitioning off non-content-determining causes, it too appears to
sneak in naturalistically unacceptable assumptions. Like all causal
theories of mental content, the asymmetric causal dependencies are
supposed to be the basis upon which meaning is created; the
dependencies are not themselves supposed to be a product, or
byproduct, of meaning. Yet, ADT appears to violate this naturalistic
pre-condition for causal theories. (This kind of objection may be
found in Seager (1993), Adams & Aizawa (1994), (1994b), Wallis
(1995), and Gibson (1996)). Ys are supposed to cause "X"s
only because Xs do and this must not be because of any semantic facts
about "X"s. So, what sort of mechanism would bring about
such asymmetric dependencies among things connected to the syntactic
item "X"? In fact, why wouldn't lots of things be
able to cause "X"s besides Xs, quite independently of the
fact that Xs do? The instantiation of "X"s in the brain
is, say, some set of neurochemical events. There should be natural
causes capable of producing such events in one's brain under a
variety of circumstances. Why on earth would foxes be able to cause
the neurochemical "X" events in us only because dogs can?
One might be tempted to observe that "X" means dog,
"Y" means fox, we associate foxes with dogs and that is
why foxes cause "X"s only because dogs cause
"X"s. We would not associate foxes with "X"s
unless we associated "X"s with dogs and foxes with dogs.
This answer, however, involves deriving the asymmetric causal
dependencies from meanings, which violates the background assumption
of the naturalization project. Unless there is a better explanation of
such asymmetrical dependencies, it may well be that the theory is
misguided in attempting to rest meaning upon them.


### 3.5 Best Test Theory



A relatively more recent causal theory is Robert Rupert's (1999)
Best Test Theory (BTT) for the meanings of natural kind terms. Unlike
most causal theories, this one is restricted in scope to just natural
kinds and terms for natural kinds. To mark this restriction, we will
let represented kinds be denoted by K's, rather than our usual
X's.



**Best Test Theory**: If a subject S bears no
extension-fixing intentions toward "X" and "X"
is an atomic natural kind term in S's language of thought (i.e.,
not a compound of two or more other natural kind terms), then
"X" has as its extension the members of natural kind K if
and only if members of K are more efficient in their causing of
"X" in S than are the members of any other natural
kind.



To put the idea succinctly, "X" means, or refers to, those
things that are the most powerful stimulants of "X". That
said, we need an account of what it is for a member of a natural kind
to be more efficient in causing "X"s than are other
natural kinds. We need an account of how to measure the power of a
stimulus. This might be explained in terms of a kind of biography.





|  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- |
|  | "X1" | "X2" | "X3" | "X4" | "X5" |
| K1 |  | 1 | 1 | 1 |  |
| K1 | 1 | 1 | 1 |  |  |
| K1 | 1 | 1 |  |  |  |
| K1 |  | 1 | 1 | 1 |  |
| K1 | 1 | 1 | 1 |  |  |
| K1 | 1 | 1 |  |  |  |
| K2 | 1 |  |  |  |  |
| K2 | 1 |  |  |  |  |
| K2 | 1 | 1 |  |  |  |
| K3 |  | 1 |  |  |  |
| K3 |  | 1 |  |  |  |
| K3 |  | 1 |  |  |  |
| K3 | 1 |  |  |  |  |



Figure 1. A spreadsheet biography




Consider an organism S that (a) causally interacts with three
different natural kinds, K1-K3, in its
environment and (b) has a language of thought with five terms
"X1"-"X5". Further,
suppose that each time S interacts with an individual of kind
Ki this causes an occurrence of one or more of
"X1"-"X5". We can then
create a kind of "spreadsheet biography" or "log of
mental activity" for S in which there is a column for each of
"X1"-"X5" and a row for
each instance in which a member of K1-K3 causes
one or more instances of
"X1"-"X5". Each mental
representation "Xi" that Ki triggers
receives a "1" in its column. Thus, a single spreadsheet
biography might look like that shown in Figure 1.



To determine what a given term "Xi" means, we
find the kind Ki that is most effective at causing
"Xi". This can be computed from S's
biography. For each Ki and "Xi", we
compute the frequency with which Ki triggers
"Xi". "X1" is tokened
four out of six times that K1 is encountered, three out of
three times that K2 is encountered, and one out of four
times that K3 is encountered. "Xi"
means that Ki that has the highest sample frequency. Thus,
in this case, "X1" means K2. Just to
be clear, when BTT claims that "Xi" means the
Ki that is the most powerful stimulant of "X",
this is not to say that "X" means the most common
stimulant of "X". In our spreadsheet biography,
K1 is the most common stimulant of
"X1", since it triggers
"X1" four times, where K2 triggers
it only three times, and K3 triggers it only one time. This
is why, according to BTT, "X1" means
K2, rather than K1 or K3.



How does the BTT handle our range of test cases? Consider, first, the
standard form of the disjunction problem, the case of "X"
meaning dog, rather than dog or fox-on-a-dark-night-at-a-distance.
Since the latter is not apparently a natural kind, "X"
cannot mean
 that.[10]
 Moreover, "X" means dog, rather than fox, because the
only times the many foxes that S encounters can trigger
"X1"s is on dark nights at a distance, where
dogs trigger "X"s more consistently under a wider range of
conditions.



How does the BTT address the apparent problem of "brain
interventions," such as LSD, microelectrodes, or brain tumors?
The answer is multi-faceted. The quickest method for taking much of
the sting out of these cases is to note that they generally do not
arise for most individuals. The Best Test Theory relies on personal
biographies in which only actual instances of kinds triggering mental
representations are used to specify causal efficiency. The
counterfactual truth that, were a stimulating microelectrode to be
applied to, say, a particular neuron, it would perfectly reliably
produce an "X" token simply does not matter for the
theory. So, for all those individuals who do not take LSD, do not have
microelectrodes inserted in their brains, do not have brain tumors,
etc., these sorts of counterfactual possibilities are irrelevant. A
second line of defense against "brain interventions"
appeals to the limitation to natural kinds. The BTT might set aside
microelectrodes, since they do not constitute a natural kind. Maybe
brain tumors are; maybe not. Unfortunately, however, LSD is a very
strong candidate for a chemical natural kind. Still the BTT is not
without a third line of defense for handling these cases. One might
suppose that LSD and brain tumors act on the brain in a rather diffuse
manner. Sometimes a dose of LSD triggers "Xi",
another time it triggers "Xj", and another time
it triggers "Xk". One might then propose that,
if one counts all these episodes with LSD, none of these will act
often enough on, say, "Xi" to get it to mean
LSD, rather than, say, dog. This is the sort of strategy that Rupert
invokes to keep mental symbols from meaning omnipresent, but
non-specific causes such as the heart. The heart might causally
contribute to "X1", but it also contributes to
so many other "Xi"s, that the heart will turn
out not to be the most efficient cause of
"X1".



What about questions? Presumably questions as a category will count as
an instance of a linguistic natural kind. Moreover, particular
sentences will also count. So, the restriction of the BTT to natural
kinds is of little use here. So, what of causal efficiency? Many
sentences appear to provoke a wide range of possible responses. In
response to, "I went to the zoo last week," S could think
of lions, tigers, bear, giraffes, monkeys, and any number of other
natural kinds. But, the question, "What animal goes 'oink,
oink'?"--perhaps uttered in "Motherese"
in a clear deliberate fashion so that it is readily comprehensible to
a child--will be rather efficient in generating thoughts of a
pig. Moreover, it could be more efficient than actual pigs, since a
child might have more experience with the question than with actual
pigs, often not figuring out that actual pigs are pigs. In such
situations, "pig" would turn out to mean "What
animal goes 'oink, oink'?," rather than pig. So,
there appear to be cases in which BTT could make *prima facie*
incorrect content assignments.



What, finally, of proximal projections of natural kinds? One plausible
line might be to maintain that proximal projections of natural kinds
are not themselves natural kinds, hence that they are automatically
excluded from the scope of the theory. This plausible line, however,
might be the only available line. Presumably, in the course of
S's life, the only way dogs can cause "X"s is by way
of causal mediators between the dogs and the "X"s. Thus,
each episode in which a dog causes an "X" is also an
episode in which a sensory projection of a dog causes an
"X". So, dog efficiency for "X" can be no
higher the efficiency of dog sensory projections. And, if it is
possible for there to be a sensory projection of a dog without there
being an actual dog, then the efficiency of the projections would be
greater than the efficiency of the dogs. So, "X" could not
mean dog. But, this problem is not necessarily damaging to BTT.



Since the BTT has not received a critical response in the literature,
we will not devote a section to objections to it. Instead, we will
leave well enough alone with our somewhat speculative treatment of how
BTT might handle our familiar test cases. The general upshot is that
the combination of actual causal efficiency over the course of an
individual's lifetime along with the restriction to natural
kinds provides a surprisingly rich means of addressing some
long-standing problems.


## 4. General Objections to Causal Theories of Mental Content



In the preceding section, we surveyed issues that face the philosopher
attempting to work out the details of a causal theory of mental
content. These issues are, therefore, one might say, internal to
causal theories. In this section, however, we shall review some of the
objections that have been brought forward to the very idea of a causal
theory of mental content. As such, these objections might be construed
as external to the project of developing a causal theory of mental
content. Some of these are coeval with causal theories and have been
addressed in the literature, but some are relatively recent and have
not been discussed in the literature. The first objections, discussed
in subsections 4.1-4.4, in one way or another push against the
idea that all content could be explained by appeal to a causal theory,
but leave open the possibility that one or another causal theory might
provide sufficiency conditions for meaning. The last objections, those
discussed in subsections 4.5-4.6 challenge the ability of causal
theories to provide even sufficiency conditions for mental
content.


### 4.1 Causal Theories do not Work for Logical and Mathematical Relations



One might think that the meanings of terms that denote mathematical or
logical relations could not be handled by a causal theory. How could a
mental version of the symbol "+" be causally connected to
the addition function? How could a mental version of the logical
symbol "!" be causally connected to the negation truth
function? The addition function and the negation function are abstract
objects. To avoid this problem, causal theories typically acquiesce
and maintain that their conditions are merely sufficient conditions on
meaning. If an object meets the conditions, then that object bears
meaning. But, the conditions are not necessary for meaning, so that
representations of abstract objects get their meaning in some other
way. Perhaps conceptual role semantics, wherein the meanings of terms
are defined in terms of the meanings of other terms, could be made to
work for these other theories.


### 4.2 Causal Theories do not Work for Vacuous Terms



Another class of potential problem cases are vacuous terms. So, for
example, people can think about unicorns, fountains of youth, or the
planet Vulcan. Cases such as these are discussed in Stampe (1977) and
Fodor (1990a), among other places. These things would be physical
objects were they to exist, but they do not, so one cannot causally
interact with them. In principle, one could say that thoughts about
such things are not counterexamples to causal theories, since causal
theories are meant only to offer sufficiency conditions for meaning.
But, this in principle reply appears to be ad hoc. It is not
warranted, for example, by the fact that these excluded meanings
involve abstract objects. There are, however, a number of options that
might be explored here.



One strategy would be to turn to the basic ontology of one's
causal theory of mental content. This is where a theory based on
nomological relations might be superior to a version that is based on
causal relations between individuals. One might say that there can be
a unicorn-"unicorn" law, even if there are no actual
unicorns. This story, however, would break down for mental
representations of individuals, such as the putative planet Vulcan.
There is no law that connects a mental representation to an
individual; laws are relations among properties.



Another strategy would be to propose that some thought symbols are
complex and can decompose into meaningful primitive constituents. One
could then allow that "X" is a kind of abbreviation for,
or logical construction of, or defined in terms of "Y1,"
"Y2," and "Y3," and that a causal theory
applies to "Y1," "Y2," and "Y3."
So, for example, one might have a thought of a unicorn, but rather
than having a single unicorn mental representation there is another
representation made up of a representation of a horse, a
representation of a horn, and a representation of the relationship
between the horse and the horn. "Horse",
"horn", and "possession," may then have
instantiated properties as their contents.


### 4.3 Causal Theories do not Work for Phenomenal Intentionality



Horgan and Tienson (2002) object to what they describe as
"strong externalist theories" that maintain that causal
connections are necessary for content. They argue, first, that mental
life involves a lot of intentional content that is constituted by
phenomenology alone. Perceptual states, such as seeing a red apple,
are intentional. They are about apples. Believing that there are more
than 10 Mersenne primes and hoping to discover a new Mersenne prime
are also intentional states, in this case about Mersenne primes. But,
all these intentional states have a phenomenology--something it
is like to be in these states. There is something it is like to see a
red apple, something different that it is like to believe there are
more than 10 Mersenne primes, and something different still that it is
like to hope to discover a new Mersenne prime. Horgan and Tienson
propose that there can be phenomenological duplicates--two
individuals with exactly the same phenomenology. Assume nothing about
these duplicates other than that they are phenomenological duplicates.
In such a situation, one can be neutral regarding how much of their
phenomenological experience is veridical and how much illusory. So,
one can be neutral on whether or not a duplicate sees a red apple or
whether there really are more than 10 Mersenne primes. This suggests
that there is a kind of intentionality--that shared by the
duplicates--that is purely phenomenological. Second, Horgan and
Tienson argue that phenomenology constitutively depends only on narrow
factors. They observe that one's experiences are often caused or
triggered by events in the environment, but that these environmental
causes are only parts of causal chains that lead to the phenomenology
itself. They do not constitute that phenomenology. The states that
constitute, or provide the supervenience base for, the phenomenology
are not the elements of the causal chain leading back into the
environment. If we combine the conclusions of these two arguments, we
get Horgan and Tienson's principal argument against any causal
theory that would maintain that causal connections are necessary for
content.



> 
> P1. There is intentional content that is constituted by phenomenology
> alone.
> 
> 
> 
> P2. Phenomenology is constituted only by narrow factors.
> 
> 
> 



Therefore,



> 
> C. There is intentional content that is constituted only by narrow
> factors.
> 



Thus, versions of causal theories that suppose that all content must
be based on causal connections are fundamentally mistaken. For those
versions of causal theories that offer only sufficiency conditions on
semantic content, however, Horgan and Tienson's argument may be
taken to provide a specific limitation on the scope of causal
theories, namely, that causal theories do not work for intentional
content that is constituted by phenomenology alone.



A relatively familiar challenge to this argument may be found in
certain representational theories of phenomenological properties.
(See, for example, Dretske (1988) and Tye (1997).) According to these
views, the phenomenology of a mental state derives from that
state's representational properties, but the representational
properties are determined by external factors, such as the environment
in which an organism finds itself. Thus, such representationalist
theories challenge premise P2 of Horgan and Tienson's
argument.


### 4.4 Causal Theories do not Work for Certain Reflexive Thoughts



Buras (2009) presents another argument that is perhaps best thought of
as providing a novel reason to think that causal theories of mental
representation only offer sufficiency conditions on meaning. This
argument begins with the premise that some mental states are about
themselves. To motivate this claim, Buras notes that some sentences
are about themselves. So, by analogy with, "This sentence is
false," which is about itself, one might think that there is a
thought, "This thought is false," that is also about
itself. Or, how about "This thought is realized in brain
tissue" or "This thought was caused by LSD"? These
appear to be about themselves. Buras' second premise is that
nothing is a cause of itself. So, "This thought is false"
is about itself, but could not be caused by itself. So, the sentence
"This thought is false" could not mean that it itself is
false in virtue of the fact that "This thought is false"
was caused by its being false. So, "This thought is false"
must get its meaning in some other way. It must get its meaning in
virtue of some other conditions of meaning acquisition.



This is not, however, exactly the way Buras develops his argument. In
the first place, he treats causal theories of mental content as
maintaining that, if "X" means X, then X causes
"X". (Cf. Buras, 2009, p. 118). He cites Stampe (1977),
Dretske (1988), and Fodor (1987) as maintaining this. Yet, Stampe,
Dretske, and Fodor explicitly formulate their theories in terms of
sufficiency conditions, so that (roughly) "X" means X, if
Xs causes "X"s, etc. (See, for example, Stampe (1977), pp.
82-3, Dretske (1988), p. 52, and Fodor (187), p. 100). In the
second place, Buras seems to draw a conclusion that is orthogonal to
the truth or falsity of causal theories of mental content. He begins
his paper with an impressively succinct statement of his argument.



Some mental states are about themselves. Nothing is a cause of itself.
So some mental states are not about their causes; they are about
things distinct from their causes (Buras, 2009, p. 117).



The causal theorist can admit that some mental states are not about
their causes, since some states are thoughts and thoughts mean what
they do in virtue of, say, the meanings of mental sentences. These
mental sentences might mean what they do in virtue of the meanings of
primitive mental representations (which may or may not mean what they
do in virtue of a causal theory of meaning) and the way in which those
primitive mental representations are put together. As was mentioned in
section 2, such a syntactically and semantically combinatorial
language of thought is a familiar background assumption for causal
theories. The conclusion that Buras may want, instead, is that there
are some thoughts that do not mean what they do in virtue of what
causes them. So, through some slight amendments, one can understand
Buras to be presenting a clarification of the scope of causal theories
of mental content or as a challenge to a particularly strong version
of causal theories, a version that takes them as offering a necessary
condition on meaning.


### 4.5 Causal Theories do Not Work for Reliable Misrepresentations



As noted above, one of the central challenges for causal theories of
mental content has been to discriminate between a "core"
content-determining causal connection, as between cows and
"cow"s, and "peripheral"
non-content-determining causal connections, as between horses and
"cow"s. Cases of reliable misrepresentations are
representations which always misrepresent in the same way. In such
cases, there is supposed to be no "core"
content-determining causal connection; there are no X's to which
"X"s are causally connected. Instead, there are only
"peripheral" causal connections. Mendelovici, (2013),
following a discussion by Hohman, (2002), suggests that color
representations may be like
 this.[11]
 Color anti-realism, according to which there are no colors in the
world, seems to be committed to the view that color representations
are not caused by colors in the world. Color representations may be
reliably tokened by something in the world, but not by colors that are
in the world.



In some instances, reliable misrepresentations provide another take on
some of the familiar content-determination problems. So, take attempts
to use normal conditions to distinguish between content-determining
causes and non-content-determining causes. Even in normal conditions,
color representations are not caused by colors, but by, say, surface
reflectances under certain conditions of illumination, just in the way
that, even in normal conditions cow representations are sometimes not
caused by cows, but by, say, a question such as, "What kind of
animal is sometimes named 'Bessie'?" Take a version
of the asymmetric dependency theory. On this theory applied to color
terms, it might seem that there is no red-to-"red" law on
which all the other laws depends in much the same way that it might
seem there is no unicorn-to-"unicorn" law on which all
other laws depends. (Cf. Fodor (1987, pp. 163-4) and (1990, pp.
100-1)).



Unlike the more familiar cases, Mendelovici, (2013), does not argue
that there actually are such problematic cases. The argument is not
that there are actual cases of reliable misrepresentations, but merely
that reliable misrepresentations are possible and that this is enough
to create trouble for causal theories of mental representation. One
sort of trouble stems from the need for a pattern of psychological
explanation. Let a mental representation "X" mean
intrinsically-heavy. Such a representation is a misrepresentation,
since there is no such property of being intrinsically heavy. Such a
misrepresentation is, nonetheless, reliable (i.e. consistent), since
it is consistently tokened by all the same sort of things on earth.
But, one can see how an agent using "X" could make a
reasonable, yet mistaken, inference to the conclusion that an object
that causes a tokening of "X" on earth would be hard to
lift on the moon. To allow such a pattern of explanation, Mendelovici
argues, a causal theorist must allow for reliable misrepresentation. A
theory of what mental representations are should not preclude such
patterns of explanation. Another sort of trouble stems from the idea
that if a theory of meaning does not allow for reliable
misrepresentation, but requires that there be a connection between
"X"s and Xs, then this would be constitute a commitment to
a realist metaphysics for Xs. While there can be good reasons for
realism, the needs of a theory of content would not seem to be a
proper source for them.



Artiga, 2013, provides a defense of teleosemantic theories in the face
of Mendelovici's examples of reliable misrepresentation. Some of
Artiga's arguments might also be used by advocates of causal
theories of mental content. Mendelovici, (2016), replies to Artiga,
2013, by providing refinements and a further defense of the view that
reliable misrepresentations are a problem for causal theories of
mental content.


### 4.6 Causal Theories Conflict with the Theory Mediation of Perception



Cummins (1997) argues that causal theories of mental content are
incompatible with the fact that one's perception of objects in
the physical environment is typically mediated by a theory. His
argument proceeds in two stages. In one stage, he argues that, on a
causal theory, for each primitive "X" there must be some
bit of machinery or mechanism that is responsible for detecting Xs.
But, since a finite device, such as the human brain, contains only a
finite amount of material, it can only generate a finite number of
primitive representations. Next, he observes that thought is
productive--that it can, in principle, generate an unbounded
number of semantically distinct representations. This means that to
generate the stock of mental representations corresponding to each of
these distinct thoughts, one must have a syntactically and
semantically combinatorial system of mental representation of the sort
found in a language of thought (LOT). More explicitly, this scheme of
mental representation must have the following properties:


1. It has a finite number of semantically primitive expressions.
2. Every expression is a concatenation of one or more primitive
expressions.
3. The content of any complex expression is a function of the
contents of the primitives and the way those primitives are
concatenated into the whole expression.



The conclusion of this first stage is, therefore, that a causal theory
of mental representation requires a LOT. In the other stage of his
argument, Cummins observes that, for a wide range of objects, their
perception is mediated by a body of theory. Thus, to perceive
dogs--for dogs to cause "dogs"--one has to know
things such as that dogs have tails, dogs have fur, and dogs four
legs. But, to know that dogs have tails, fur, and four legs, one needs
a set of mental representations, such as "tail",
"fur", "four", and "legs". Now the
problem fully emerges. According to causal theories, having an
"X" representation requires the ability to detect dogs.
But, the ability to detect dogs requires a theory of dogs. But, having
a theory of dogs requires already having a LOT--a system of
mental representation. One cannot generate mental representations
without already having
 them.[12]


### 4.7 Causal Theories Conflict with the Implementation of Psychological Laws



Jason Bridges (2006) argues that the core hypothesis of informational
semantics conflicts with the idea that psychological laws are
non-basic. As we have just observed, causal theories are often taken
to offer mere sufficiency conditions for meaning. Suppose, therefore,
that we suitably restrict the scope of a causal theory and understand
its core hypothesis as asserting that all "X"s with the
content X are reliably caused by X. (Nothing in the logic of
Bridges' argument depends on any additional conditions on a
putative causal theory of mental content, so for simplicity we can
follow Bridges in restricting attention to this simple version.)
Bridges proposes that this core claim of a causal theory of mental
content is a constitution thesis. It specifies what constitutes the
meaning relation (at least in some restricted domain). Thus, if one
were to ask, "Why is it that all 'X's with content X
are reliably caused by Xs?," the answer is roughly,
"That's just what it is for 'X' to have the
content X". Being caused in that way is what constitutes having
that meaning. So, when a theory invokes this kind of constitutive
relation, there is this kind of constitutive explanation. So, the
first premise of Bridges' argument is that causal theories
specify a constitutive relation between meaning and reliable causal
connection.



Bridges next observes that causal theorists typically maintain that
the putative fact that all "X"s are reliably caused by Xs
is mediated by underlying mechanisms of one sort or another. So,
"X"s might be reliably caused by dogs in part through the
mediation of a person's visual system or auditory system.
One's visual apparatus might causally connect particular
patterns of color and luminance produced by dogs to "X"s.
One might put the point somewhat differently by saying that a causal
theorist's hypothetical "Xs causes 'X's"
law is not a basic or fundamental law of nature, but an implemented
law.



Bridges' third premise is a principle that he takes to be nearly
self-evident, once understood. We can develop a better first-pass
understanding of Bridges' argument if, at the risk of distorting
the argument, we consider a slightly simplified version of this
principle:



> 
> (S) If it is a true constitutive claim that all *f*s are
> *g*s, then it's not an implemented law that all
> *f*s are *g*s.
> 



To illustrate the principle, suppose we say that gold is identical to
the element with atomic number 79, that all gold has atomic number 79.
Then suppose one were to ask, "Why is it that all gold has the
atomic number 79?" The answer would be, "Gold *just
is* the element with atomic number 79." This would be a
constitutive explanation. According to (S), however, this constitutive
explanation precludes giving a further mechanistic explanation of why
gold has atomic number 79. There is no mechanism by which gold gets
atomic number 79. Having atomic number 79 just is what makes gold
gold.



So, here is the argument



> 
> P1. It is a true constitutive claim that all "X"s with
> content X are reliably caused by Xs.
>   
> 
> P2. If it is a true constitutive claim that all "X"s with
> content X are reliably caused by Xs, then it is not an implemented law
> that all "X"s with content X are reliably caused by Xs.
> 



Therefore, by *modus ponens* on P1 and P2,



> 
> C1. It is not an implemented law that all "X"s with
> content X are reliably caused by Xs.
> 



But, C1 contradicts the common assumption



> 
> P3. It is an implemented law that all "X"s with content X
> are reliably caused by
>  Xs.[13]
> 



Rupert (2008) challenges the first premise of Bridges' argument
on two scores. First, he notes that claims about constitutive natures
have modal implications which at least some naturalistic philosophers
have found objectionable. Second, he claims that natural scientists do
not appeal to constitutive natures, so that one need not develop a
theory of mental content that invokes them.


### 4.8 Causal Theories do not Provide a Metasemantic Theory



In discussing informational variants of causal theories, Artiga &
Sebastian, 2020, have proposed a new "metasemantic"
problem. They correctly note that there is a difference between
explaining why "X" means X, rather than Y, and explaining
why "X" has a meaning at all. Moreover, they correctly
note that having an answer to this first question does not necessarily
answer the second question. But, it is unclear that the metasemantic
problem is serious. If one's theory is that "X"
means X if A, B, and C, then that would seem to provide an answer to
the metasemantic question. Why does "X" mean anything at
all? Because "X" meets sufficiency conditions A, B, and C.
In other words, insofar as there is a question to be answered, it
appears that all theories provide one.


## 5. Concluding Remarks



Although philosophers and cognitive scientists frequently propose to
dispense with (one or another sort of) mental representation (cf.,
e.g., Stich, 1983, Brooks, 1991, van Gelder, 1995, Haugeland, 1999,
Johnson, 2007, Chemero, 2009), this is universally accepted to be a
revolutionary shift in thinking about minds. Short of taking on board
such radical views, one will naturally want some explanation of how
mental representations arise. In attempting such explanations, causal
theories have been widely perceived to have numerous attractive
features. If, for example, one use for mental representations is to
help one keep track of events in the world, then some causal
connection between mind and world makes sense. This attractiveness has
been enough to motivate new causal theories (e.g. Rupert, 1999, Usher,
2001, and Ryder, 2004), despite the widespread recognition of serious
challenges to an earlier generation of theories developed by Stampe,
Dretske, Fodor, and others.