## 1. Analyses of Disposition Ascriptions



Many terms have been used to describe what we mean by dispositions:
'power' (Locke's term), 'dunamis' (Aristotle's
term), 'ability', 'potency',
'capability', 'tendency',
'potentiality', 'proclivity',
'capacity', and so forth. In a very general sense, they
mean disposition, or otherwise something close by. To avoid confusion,
however, we will stick to the term 'disposition' (for a
subtle difference between dispositions and powers, see Bird 2016).



As noted earlier, philosophical interests in dispositions principally
centre around the issue of how to explain them in more readily
understandable terms. This issue came to the prominence in the early
20th century when philosophers aspired to construct an
empiricist language in which all meaningful sentences including
dispositional sentences can be analyzed in observational and
extensional-logical terms. One early attempt at analyzing disposition
ascriptions on the empiricist program is made by Carnap (1928,
1936-7) who considers the so-called reduction sentences as a way
of introducing dispositional expressions into our language:



**R.** 
For each object \(x\), if \(x\) is put into water, it is
soluble iff it dissolves,



where the conditional is understood as a material conditional. The
idea behind \(R\) is that we can meaningfully tell whether or not a
given item is soluble only if it is put into water. \(R\) thus provides
a rule for how to introduce the dispositional predicate
'soluble' in application to items that have in fact been
put into water. But \(R\) is silent about whether \(x\) is soluble
when it is not put into water, and this means that we cannot use \(R\)
to completely eliminate the predicate 'soluble' from the
language. Though this is what Carnap explicitly embraced, many
philosophers found it deeply problematic. And so philosophers of
empiricist leanings continued the search for a definition schema of
dispositional expressions in an extensional language (Kaila 1939,
1942; Storer 1951).



Notwithstanding these attempts, however, it came to be widely accepted
that disposition ascriptions cannot be analyzed in an extensional
language (Burks 1951, 1955; Pap 1958; Sellars 1958). This had the
effect of turning philosophers' attention to the connection
between disposition ascriptions and counterfactual or subjunctive
conditionals. In fact, it was generally recognised from the very
beginning of philosophical research about dispositions that
disposition ascriptions are closely linked with counterfactual
conditionals: '\(x\) is soluble at \(t\)' is
associated with '\(x\) would dissolve if put into water at
\(t\)'. This idea, however, was overlooked for decades
partly due to the then popular epistemology of radically empiricist
kind and partly due to the lack of a proper semantic understanding of
counterfactual conditionals. But it later came to be brought into the
spotlight largely due to the revival of the philosophy of modality
from the early 1970s. (For a historical survey of the debate regarding
conceptual analyses of dispositions, see Malzkorn 2001 and Bird
2012.)


### 1.1 Conventional and Canonical Dispositions



As is already clear, analyses of dispositions usually proceed on the
assumption that, for any disposition, we can identify its stimulus
conditions and manifestations. It is typically said that dispositions
would exhibit their 'characteristic manifestations' under
some 'stimulus conditions'. However, most conventional
dispositional predicates--'fragile',
'soluble', 'malleable' and the like--make
no explicit reference to the stimulus conditions and manifestations
for the properties they express and the assumption that we are
nonetheless in a position to identify those stimulus conditions and
manifestations is controversial. The stimulus condition and
manifestation of (water-)solubility are typically assumed to be the
event of being put into water and the event of dissolving,
respectively, and perhaps uncontroversially so. But what are the
manifestations of fragility? Something like shattering or cracking, it
seems. But what about splintering, or breaking cleanly in two, or, as
with a fragile house of cards, collapsing? It seems hard to say. And
what exactly are the stimulus conditions of fragility? Striking, it
seems. But what about twisting or shaking? We are at a loss. But do
these questions have to do with philosophical understanding of
dispositions at all?



Partly due to the difficulty of specifying precisely the stimulus
conditions and manifestations of a disposition and partly due to the
doubt over its philosophical relevance, philosophers find it useful to
distinguish two sorts of disposition, or alternatively, two ways of
referring to dispositions. Conventional dispositions are typically
expressed by such simple predicates as 'fragile',
'soluble', 'flammable', and so on, which
include no explicit reference to their stimulus conditions and
manifestations. Canonical dispositions, on the other hand, are
explicit about their stimulus conditions and manifestations, couched
in the overtly dispositional locution. Some examples of canonical
dispositions are the disposition to break in response to being struck,
the disposition to cause death in response to being ingested, and so
on. Obviously, the two ways of expressing dispositional properties are
related to one another. As noted earlier, (water-)solubility might be
identified with the disposition to dissolve in response to being put
into water although this kind of identification is not readily
available in many other cases of conventional disposition. This
distinction between conventional and canonical dispositions allows us
to keep questions about the adequacy of different analyses of
dispositions sharply distinct from questions about how to identify the
stimulus conditions and manifestations of particular dispositions.



Having introduced this distinction, we can facilitate the quest for an
analysis of dispositions by separating two issues, the issue of
providing a conceptual analysis of canonical dispositions and the
issue of explaining conventional dispositions in terms of canonical
dispositions. What do we mean by saying that \(x\) is
poisonous? The first step for answering this question is to transform
the conventional disposition of being poisonous into the corresponding
(group of) canonical disposition(s) by specifying its stimulus
conditions and manifestations. The second step is to seek a conceptual
analysis of the canonical disposition(s) at hand. On this
'two-step' approach, first taken by Lewis (1997), the
so-called conditional analyses of dispositions we will discuss below
are designed to help with the second step, saying how to analyze
canonical dispositions in terms of counterfactual conditionals. This
approach has the advantage of allowing us to clarify what it takes to
give an analysis of dispositions.


### 1.2 The Simple Conditional Analysis and Counterexamples



The simplest analysis of dispositions in terms of counterfactual
conditionals is the Simple Conditional Analysis:



**SCA.**
An object is disposed to \(M\) when \(C\) iff it
would \(M\) if it were the case that \(C\).



Notice that the analysandum of *SCA* is an ascription
of a
schematic *canonical* disposition. *SCA* has
been explicitly endorsed by Ryle (1949), Goodman (1954), and Quine
(1960) and implicitly by countless others.



Counterexamples to *SCA* first raised by Martin
(1994) exploit the fact that some dispositions are
'finkish' in the sense that the conditions for an object's
acquiring or losing disposition \(D\) might be the same
as \(D\)'s stimulus conditions. Suppose that an electrical
wire is live just in case it has the canonical disposition to conduct
electricity when touched by a conductor. (This is an artificial
definition that might differ from a dictionary definition of
'live'.) *SCA* then entails that a wire
is live iff it would conduct electricity if touched by a conductor.
Suppose now that a dead wire is connected to an electro-fink, a device
which senses when the wire is about to be touched by a conductor, and
which makes the wire live in every such circumstance. If the wire were
touched by a conductor then, thanks to the work of the device, the
wire would become live, and so would conduct electricity. Hence the
wire would conduct electricity if touched by a conductor. Being dead,
however, it is not disposed to conduct electricity when touched by a
conductor. The device can also operate on a reverse cycle, attaching
to a naturally live wire but removing its property of being live if
ever it is touched by a conductor. In this case, although the wire is
disposed to conduct electricity when touched by a conductor, the
'reverse-cycle' fink ensures that the associated
counterfactual conditional is false. Martin's examples are special
cases of what R. K. Shope (1978) calls 'The Conditional Fallacy
in Contemporary Philosophy', roughly the fallacy of ignoring the
fact that, in a purported conditional analysis, the truth or falsity
of the analysandum might depend on the truth or falsity of the
antecedent of the conditional analysans.



Another kind of counterexample to *SCA*, due to Johnston
(1992) and Bird (1998), involves a fragile glass that is carefully
protected by packing material. It is claimed that the glass is
disposed to break when struck but, if struck, it wouldn't break thanks
to the work of the packing material. There is an important difference
between this example and Martin's: the packing material would prevent
the breaking of the glass not by *removing* its
disposition to break when struck but by blocking the process that
would otherwise lead from striking to breaking. This difference will
be important in the context of evaluating Lewis's analysis of
dispositions in
 section 1.4.
 The packing material is called a masker (Johnston) or antidote (Bird)
to the glass's disposition at issue (see Choi 2003 for a refinement of
the masking counterexample to *SCA*).



Still another kind of counterexample to *SCA*, discussed
by Smith (1977), Prior, Pargetter & Jackson (1982), Lewis (1997),
and Armstrong (1997), involves an interfering factor in virtue of
which \(x\) *mimics* the manifestation of
disposition \(D\) although it does not
possess \(D\). When a styrofoam dish is struck, it makes a
distinctive sound. The Hater of Styrofoam is within earshot of it.
What if it were struck? The Hater of Styrofoam would hear the
distinctive sound and tear the styrofoam dish apart. It seems evident
that the dish is not disposed to break when struck. If struck,
however, it would break due to the interference of the Hater of
Styrofoam, which goes against *SCA*. Here the Hater of
Styrofoam is called a mimicker of the disposition to break when
struck, meaning that it makes it the case that the dish, which does
not have the disposition, mimics its manifestation. (This example is
due to Lewis 1997.)



Notice that finking, masking and mimicking situations are ubiquitous
(Fara 2005). Extremely fragile and valuable objects, for example,
are *routinely* protected by various kinds of
packaging material. See also Bird 1998.


### 1.3 Defending the Simple Conditional Analysis



Despite the apparent force, however, it is not universally agreed that
these examples undermine *SCA*. Some philosophers insist
that *SCA*, when properly understood, is not susceptible
at all to the alleged counterexamples, whilst some others maintain
that they do refute *SCA* but they can be avoided by
suitable sophistications of it. The first position is supported by
Choi (2006, 2008) and Gundersen (2002), who challenge the assumption
about what dispositions an object possesses in each of the alleged
counterexamples. They emphasise that when the glass is protected by
the packing material it is *no longer* disposed to
break when struck; rather, it is disposed to break when
struck *in the absence of the packing material*. This is
in line with *SCA* since the glass would indeed break
if struck in the absence of the packing material although it wouldn't
break if struck under its current conditions--*mutatis
mutandis* for the example of reverse-cycle finks. Similarly,
Choi suggests that when the styrofoam dish is in the neighborhood of
the Hater of Styrofoam, it is indeed disposed to break when struck; it
is not disposed to break when struck *in the absence of the
Hater of Styrofoam*. This suggestion is consistent
with *SCA* since the dish wouldn't break if struck in
the absence of the Hater of Styrofoam although it would break if
struck under its current conditions--*mutatis
mutandis* for the example of finks.



This tactic can be readily generalised so as to distinguish two
dispositions, the simple disposition whose stimulus condition and
manifestation are the event of being struck and the event of breaking,
respectively, on the one hand, and the complex disposition whose
stimulus condition and manifestation are the event of being
struck *in the absence of finks, reverse*-*cycle
finks, maskers, and mimickers* and the event of breaking,
respectively, on the other. The simple counterfactual conditional
associated with the first disposition (namely,
'if \(x\) were struck it would break') is
false in the examples of reverse-cycle finks and maskers and true in
the examples of finks and mimickers but the ascription of the first
disposition (namely, '\(x\) is disposed to break when
struck') correspondingly has the same truth value in each
example; meanwhile, the ascription of the second disposition (namely,
'\(x\) is disposed to break when struck *in the
absence of finks, reverse*-*cycle finks, maskers, and
mimickers*') is true in the examples of reverse-cycle finks
and maskers and false in the examples of finks and mimickers but the
simple counterfactual conditional associated with the second
disposition (namely, 'if \(x\) were
struck *in the absence of finks, reverse*-*cycle
finks, maskers, and mimickers* it would break')
correspondingly has the same truth value in each example.



Manley & Wasserman (2008) object that this defence
of *SCA* falls prey to what they call the problem of
'Achilles' heels' (for more on Manley & Wasserman's
objection, see Bonevac, Dever & Sosa 2011; Choi 2011b; Manley
& Wasserman 2011). Hajek (forthcoming) agrees with Choi and
Gundersen that the alleged counterexamples to *SCA* fail but
disagrees with them, arguing that *SCA* is susceptible to what
he calls 'minkish' counterexamples. Another line of
criticism of Choi and Gundersen's strategy is to appeal to the
intrinsicness of dispositions, which we will discuss in the next
section.


### 1.4 Sophisticated Analyses



The typical reaction to the counterexamples is to take them to
motivate a sophisticated conditional analysis. Versions of
sophisticated analyses of dispositions have been offered by Prior
(1985), Lewis (1997), Malzkorn (2000), Mellor (2000), Fara (2005),
Manley & Wasserman (2008), Vetter (2014, 2015), and Kroll (2017).
Here we will focus on Lewis's, Manley & Wasserman's, and Vetter's
analyses.



Lewis (1997) points out that if Martin's examples are to succeed as
counterexamples to *SCA* then we must suppose
that \(x\)'s dispositions are intimately related to its
intrinsic properties. For consider again Martin's example of an
apparently dead wire attached to an electro-fink. Choi and Gundersen's
defence of *SCA* rests on the insistence that the
wire is not dead but live. But we can imagine its intrinsic duplicate
unconnected to an electro-fink, which is unquestionably dead. Choi and
Gundersen's defence therefore has the consequence that whether the
wire is live or dead is an *extrinsic* matter. When
Martin's examples are supplemented with the assumption that
dispositions involved in the examples are intrinsic to their bearers,
therefore, this will preclude Choi and Gundersen's defence
of *SCA*. And so, Lewis, subscribing to the Intrinsic
Dispositions Thesis (for short, IDT) that all dispositions are
intrinsic to their bearers, concludes that Martin's examples have left
no hope for *SCA*. But is IDT true? We will discuss it
later in
 section 5.



Lewis's proposal (with some simplifications) is:



**RCA.** 
An object \(x\) is disposed to \(M\) when \(C\) iff \(x\) has an
intrinsic property \(B\) such that, if it were the case that \(C\),
and if \(x\) were to retain \(B\) for a sufficient time, then \(C\)
and \(B\) would jointly cause \(x\) to \(M\).



Lewis's amendment enables us to circumvent the problem of finks and
reverse-cycle finks. Martin's live wire connected to the reverse-cycle
fink, for example, is correctly predicted to be live. For the wire has
an intrinsic property--the property of having free electrons,
say--such that, if it were touched by a conductor, *and
if it were to retain that property* for a sufficient time,
then the wire would conduct electricity (because of being touched and
having the property).



It seems, though, that Lewis's amendment doesn't help with the
problems of maskers and mimickers (Bird 1998; Fara 2005; Choi 2005a).
Recall the fragile glass carefully protected with the packing
material. The glass, it is thought, is disposed to break when struck.
What if it were struck? It would retain all of its molecular
structures for a sufficient time. But it would not break because of
the masking operation of the packing material.
So *RCA* seems to fail.
Similarly, *RCA* doesn't avoid the problem of
mimickers. The styrofoam dish, if struck, would break by the mimicking
operation of the Hater of Styrofoam. Note that, if struck, the dish
would retain for a sufficient time an intrinsic property, say, the
microstructure responsible for its distinctive sound and, further,
this intrinsic property would be a cause of the breaking. The
prediction by *RCA* is therefore that the styrofoam
dish is disposed to break when struck, which might be claimed to be
counterintuitive.



In an effort to deflect the problem of maskers, Lewis employs what
Manley & Wasserman (2008) name *the strategy of getting
specific*. He suggests that we have a choice. We might, on the one
hand, say that the protected glass is disposed to break when struck
without the packing material; or we might say, instead, that it is
disposed to break when struck but this disposition is masked by the
packing material. Lewis insinuates that the first option is preferable
to the second one. The first option being taken, however, one may well
insist that the glass is not disposed to break when struck, which
neutralises the problem of maskers. (Note that the strategy of getting
specific is basically the same as the one Choi and Gundersen take to
deal with the problems of finks, reverse-finks, and mimickers as well
as the problem of maskers.)



Lewis's response to the problem of mimickers, on the other hand, is to
invoke the idea that the manifestation of fragility is not
simply \(x\)'s breaking but \(x\)'s
breaking *through a certain direct and standard process*.
The styrofoam dish, if struck, would break but not through a certain
direct and standard process for fragility, a process that does not
involve the Hater of Styrofoam's intervention. Then the dish is not
fragile as it is not disposed to break through a certain direct and
standard process if struck. Having explained away the intuition that
the dish is not fragile, it opens the possibility of insisting that,
given that the dish is situated within the earshot of the Hater of
Styrofoam, it is indeed disposed to break when struck, which
neutralises the problem of mimickers. (See Choi 2005a for a criticism
of Lewis's response.)



We have three comments to add on Lewis's responses. The first comment
is that Lewis denies that the problems of maskers and mimickers throw
light on *the analysis of dispositionality* that
philosophers intend to attain by the conditional analysis of
dispositions. On his view, they touch upon merely the pragmatic issue
of what specifications are built into the stimulus conditions and
manifestations corresponding to a given dispositional concept. This is
disputed by Choi (2008). Secondly, there is a
noticeable *tension* between Lewis's criticism
of *SCA* and his defence of *RCA* from
the problems of maskers and mimickers. We have seen earlier that Lewis
tries to add force to the problem of finks by assuming IDT. But this
assumption seems to undermine his own defence
of *RCA* from the problems of maskers and mimickers.
Lewis's response to the problem of maskers is that the protected glass
is disposed to break when struck without the packing material, which
explains away the intuition that it is fragile; and that this opens
the door for insisting that it is in fact not disposed to break when
struck. But this move seems to be on a collision course with IDT
because an unprotected intrinsic duplicate of the glass is undoubtedly
disposed to break when struck. This illustrates the tension between
Lewis's treatments of the problems of finks and
maskers--and *mutatis mutandis* for the problems
of mimickers (see Choi 2009 for discussion).



To introduce the third comment on Lewis's approach, let us compare it
with Choi and Gundersen's approach that rules out finks, reverse-cycle
finks, maskers, mimickers, etc., from the stimulus condition. A
conspicuous difference between them is that, whilst, on Choi and
Gundersen's approach, all of the problems of finks, reverse-cycle
finks, maskers, and mimickers are handled in a
*uniform* manner, this is not the case for Lewis's
approach. Lewis deals with them by
invoking *diverse* elements in *RCA*: the
condition that \(x\) retain an intrinsic property for a
sufficient time, the condition that the intrinsic property causally
contribute to the occurrence of the manifestation, the condition that
maskers be absent from the stimulus condition, the condition that the
manifestation of fragility be \(x\)'s breaking through a
certain direct and standard process. Other things being equal, this
difference will favour Choi and Gundersen's approach over Lewis's as
explanatory unity is a theoretical virtue. (See Gundersen 2017 and
Schlosser 2018 for an ongoing dispute about *RCA*'s
viability.)



Having discussed Lewis's analysis of dispositions in detail, let us
turn to a more recent proposal by Manley & Wasserman (2007, 2008).
They take cues from, among other things, *comparative
disposition ascriptions* like '\(x\) is more
disposed to break when struck than \(y\)'. They stress
that the versions of the conditional analysis of dispositions
discussed so far cannot accommodate these comparative ascriptions as
counterfactual conditionals invoked by conditional analyses do not
admit of degree. This consideration suggests the following account of
dispositions, or so they argue.



**PROP.** 
\(x\) is disposed to \(M\) in \(C\) iff some suitable proportion of
\(C\)-cases are such that \(x\) would \(M\) in them,




where a \(C\)-case is a fully specific scenario that
settles everything causally relevant to the manifestation of the
disposition. The suitable proportion of \(C\)-cases is
fixed partly by the stimulus condition \(C\) and partly
by the context of ascription.



On *PROP*, '\(x\) is more disposed
to \(M\) in \(C\) than \(y\)'
means that \(x\) would \(M\) in a
greater proportion of \(C\)-cases
than \(y\). *PROP* thus seems to provide an
account of comparative disposition ascriptions. Further, Manley &
Wasserman hold that *PROP* has no difficulty handling
some apparent counterexamples to the conditional analyses of
dispositions on offer. A fragile glass wouldn't break in the presence
of finks or maskers. *PROP*, however, rules correctly that it
is disposed to break when struck. That is because the glass would
still break in a suitable proportion of \(C\)-cases where it is
struck. On the other hand, a non-fragile steel bar would break in the
presence of reverse-finks or mimicker. Yet again, *PROP*
entails correctly that it is not disposed to break when struck. That
is because the steel bar wouldn't break in a suitable proportion of
\(C\)-cases where it is struck.



But Manley & Wasserman's analysis is not without difficulties. The
trouble is that it is *extremely* difficult to make
sense of talk of proportions of \(C\)-cases,
especially given that very diverse factors are supposed to affect the
weights of given \(C\)-cases: closeness of them to
actuality, contextual variations of their weights, and so on. In
addition, Manley & Wasserman's account of comparative disposition
ascriptions requires a non-arbitrary standard for comparing the sizes
of infinite sets of \(C\)-cases despite most of them
being of the *same* cardinality. But it looks to be a
tremendous task to set up such a standard, let alone, to do so in a
way that is epistemically accessible to those of us who possess the
dispositional concepts at issue.



Vetter (2014, 2015) challenges what she calls 'the standard
conception of dispositionality', according to which a
disposition \(D\) is individuated by the pair of its stimulus
condition \(S\) and its manifestation \(M\), and its modal
nature is at least approximately captured by a counterfactual
conditional 'If \(x\) were in \(S, x\) would
\(M\rsquo\). The alternative she proposes is the possibility
conception of dispositionality according to which a disposition is
individuated by its manifestation \(M\) alone and its modal
nature is that of possibility, best characterised by '\(x\)
can \(M\rsquo.\) On this conception, the stimulus condition
plays no role in individuating dispositions. Hence dispositional
sentences are akin to 'can' sentences. With this in the
background, Vetter first proposes an analysis of comparative
dispositional ascriptions which says that \(x\) is more disposed
to \(M\) than \(y\) iff \(x\) would \(M\) in more
cases than \(y\), where cases are triples of a world, a time, and
an object. For instance, to say that \(x\) is more disposed to
break than \(y\) is to say that \(x\) would break in more
cases than \(y\). Vetter then proposes that \(x\) is
disposed to break *simpliciter* just in case it breaks in a
sufficiently large proportion of the relevant cases, where context may
determine what counts as sufficiently large.



Vetter's proposal has much in common with Manley & Wasserman's,
which means that the former inherits many of the latter's advantages
and disadvantages. The key difference between them is that Manley
& Wasserman, along with other defenders of conditional analyses of
dispositions, hold on to the standard conception that the essential
characterization of a disposition requires a reference to its stimulus
condition as well as its manifestation but Vetter opposes this
conception. It remains to be seen how this difference will be
settled.


### 1.5 Analyzing Conventional Dispositions



We have thus far surveyed a variety of conceptual analyses of
canonical dispositions that involve explicit references to their
stimulus conditions and manifestations. This corresponds to the second
step in Lewis's two-step approach (see
 section 1.1).
 But they by themselves do not tell us how to understand conceptually
conventional dispositions like fragility, flammability, conductivity,
etc., that do not involve such explicit references. Here it might be
suggested that, given that conventional dispositions are the ones we
are most familiar with and find most useful in everyday or scientific
contexts, our understanding of dispositions will remain incomplete
unless we have obtained a full-blooded analysis of conventional
dispositions. In fact, although the apparent counterexamples to
*SCA* were presented in terms
of *canonical* dispositions in the preceding
sections, they are often presented in terms
of *conventional* dispositions. On this construal,
the simple conditional analysis is thought of as an analysis of
conventional dispositions. For instance, the simple conditional
analysis of fragility is understood as saying
that \(x\) is *fragile* at \(t\) iff
it would break if struck at \(t\); and this analysis is
claimed to be toppled, for example, by a carefully packed glass that
remains fragile but would not break if struck. Thus the alleged
counterexamples are often described as concerning the issue of how to
link conventional dispositions with counterfactual conditionals. We
noted earlier, though, that, to tackle this issue, we need define
conventional dispositions into (groups of) canonical dispositions by
specifying their stimulus conditions and manifestations, which
corresponds to the first step in Lewis's two-step approach. With this
in mind, we will inquire into the issue of how to specify the stimulus
conditions and manifestations of conventional dispositions and other
related issues.



Let us start by unraveling
several *different* notions of stimulus condition.
Mary utters 'Arsenic is poisonous'. What is the stimulus
condition of the disposition expressed by 'poisonous'? An
impromptu answer would be the event of being ingested. In most normal
contexts of utterance, however, what she means is that arsenic is
poisonous *to humans*. So, given this context of utterance, the
stimulus condition can be said to be the event of being ingested
*by a human being* (Prior 1985, chapter 1). This second
stimulus condition can be identified by making explicit the context's
contribution to the content of the stimulus condition. As we will see,
furthermore, it has been suggested that the stimulus condition is not
the simple event of being ingested but the event of being ingested
*without finks, maskers, and so forth*. Here the condition of
the absence of finks, maskers, and so forth seems to come not from the
context of utterance but from the context-independent meaning of being
poisonous (Choi 2011a, 2011b). There are thus many different notions
of stimulus condition although they are not miles away from each
other. One says 'My mobile phone set is fragile'. The
stimulus condition could be any of its being struck, its being struck
with a soft blow, its being struck without finks, maskers, and so
forth.



This disambiguation is of much value when we articulate the notion of
'multi-track' disposition. There seems to be a general
agreement that there are so-called 'multi-track'
conventional dispositions that correspond to more than one pair of
stimulus condition and manifestation (Ryle 1949, pp. 43-45; Bird
2005a, p. 367; Bird 2007a, pp. 21-24; Ellis & Lierse 1994,
p. 29; Williams 2011, pp. 85-7; Vetter 2013). The thought is that
exactly the same conventional dispositions may be picked out by
multiple characterisations in terms of stimulus condition and
manifestation. However, caution is required when we decide if a given
disposition is multi-track or not. First of all, a single notion of
stimulus condition must be in use: it is wrong to infer that the
property of being poisonous is a multi-track disposition, from the
fact that its stimulus condition could be being ingested, being
ingested by humans, being ingested without finks, maskers, and so on.
Further, we must hold the context of utterance fixed: it is wrong to
infer that the property of being poisonous is multi-track, from the
fact that its stimulus condition could be being ingested by humans,
being ingested by dogs, being ingested by birds, and so on. The
expression 'poisonous' is context-sensitive with respect
to who \(x\) is poisonous to, referring to different dispositions
relative to different contexts of utterance. Hence stimulus conditions
like \(x\)'s being ingested by humans, \(x\)'s
being ingested by dogs, etc., are not stimulus conditions of
the *same* disposition. And hence they don't have to
do with the issue of whether or not a given disposition is
multi-track.



It is not universally agreed that dispositions are typically
multi-track. Lowe (2010, pp. 10-11) insists that dispositions can't be
multi-track. A majority of metaphysicians, however, lean toward the
multi-track character of dispositions. Being electrically charged, an
electron is disposed to experience an electrostatic
force \(F\) in response to being placed at a
distance \(d\) away from an electric
charge \(q\) but it is also disposed to experience an
electrostatic force \(F^\*\) in response to being placed
at a distance \(d^\*\) away from an electric
charge \(q^\*\). Similarly, it might be plausibly claimed that
fragility is a multi-track disposition with many different stimulus
conditions: \(x\)'s being struck, \(x\)'s being
stressed, \(x\)'s being twisted, \(x\)'s being
shaken, and so on. Indeed, whilst Cartwright's (1999, pp. 59, 64)
notion of capacity is akin to the notion of multi-track disposition
(cf. Teller 2002, pp. 717-718), electric charge being a paradigm
example of capacity in Cartwright's sense, she maintains that
capacities are real properties and that reference to capacities is
essential in the operation of science: scientific laws are nothing but
expressions of what capacities exist and how they work together. On
Cartwright's view, hence, not only do multi-track dispositions exist
but it is their nature that science aims to unveil.



Vetter (2013) goes a step further to argue that the extent of the
multi-track character of dispositions is severely underestimated,
exploiting what she calls the problems of qualitative diversity and
quantitative diversity. It is noteworthy that this consideration is
used as a stepping stone for her possibility conception of
dispositionality. The thought is that, given that there is an extreme
variety of stimulus conditions of \(D\) and that there is no
privileged subset of them with respect to the question of whether
\(x\) instantiates \(D\) or not, we'd better embrace
dispositions without stimulus conditions (Vetter 2014, p. 132).



Be that as it may, however, we will leave behind multi-track
dispositions, for, seeking a conceptual analysis of them raises many
difficult questions that would take us far afield. In what follows, we
will instead focus on single-track conventional dispositions that
correspond to a unique pair of stimulus condition and manifestation,
or alternatively we will simply assume that all conventional
dispositions are single-track. We hope, though, the subsequent
discussion will shed light on the issue of how to analyze multi-track
dispositions.



What are the stimulus condition and manifestation of a given
conventional disposition? It is generally held that any specification
of the stimulus condition of a conventional disposition must include
covert reference to a *ceteris paribus* clause (Prior
1985; Lewis 1997; Bird 1998; Mumford 1998; Mellor 2000; Malzkorn 2000;
Cross 2005; Choi 2006, 2008; Hauska 2008b; Steinberg 2010): fragility,
for example, is defined not as the canonical disposition to break when
struck but rather as the canonical disposition to break when
struck *under certain standard conditions*. For the sake
of simplicity, let us combine this definition with *SCA*. Then it follows that
'\(x\) is fragile' is to be analyzed into
'If \(x\) were struck under certain standard
conditions it would break' or
'If \(x\) were struck then, *ceteris
paribus*, it would break'. Recall that, in each of the
alleged counterexamples to *SCA*, a fragile thing but not
a non-fragile thing would break if struck in the absence of finks,
reverse-cycle finks, maskers, mimickers, and so on. To the extent to
which cases of finks, reverse-cycle finks, etc., are non-standard,
therefore, the *ceteris paribus* clause ensures that
'\(x\) is fragile' has the same truth value as
the associated counterfactual conditional in every case, thereby
blocking the counterexamples.



But serious doubts have been raised as to how to spell out
the *ceteris paribus* clause in a way that fits the
bill. It is even claimed that the only way to spell it out in such a
way is to render the proposed analysis *vacuous*. For, on
the intended reading of the *ceteris paribus* clause,
to say that if \(x\) were struck, then *ceteris
paribus* it would break seems to be simply to say that if it
were struck then, unless it didn't break, it would break, which is
vacuously true (Martin 1994; Bird 1998; Mumford 1998, 2001; Fara 2005
and Hauska 2008b) See Mellor 2000 and Steinberg 2010 for the view that
the risk of vacuity is unproblematic. See also Choi 2008 and Steinberg
& Steinberg 2017 for an attempt to spell out the *ceteris
paribus* clauses in a way that does not render the resulting
conditionals vacuous.



The task of analyzing conventional dispositions poses no additional
challenge to Manley & Wasserman's approach or Vetter's approach,
additional to those challenges posed by the task of analyzing
canonical dispositions. They handle the problems of finks, maskers,
mimickers, etc., not by ruling them out from the stimulus condition
but by exploiting the 'suitable proportion' requirement.
They can thereby stick to the simple definition of fragility as the
disposition to break when struck (Manley & Wasserman) or as the
disposition to break (Vetter). From their respective analysis of
canonical dispositions, then, they can readily derive an analysis of
conventional dispositions like fragility that does away with
*ceteris paribus clauses*.


## 2. The Dispositional/Categorical Distinction



The previous section was devoted to the issue of how to devise a
conceptual analysis of dispositions in an attempt to improve our
understanding of dispositions. Another way of improving it is to
identify characteristics that distinguish dispositions from
non-dispositional properties, especially, 'categorical
properties'. What are categorical properties? With respect to
this question we are in no better position than we are with respect to
dispositional properties. There are some clear cases like
*roundness* and *having two arms*. But it is not clear
what characteristics they have in common. See Mumford 1998, pp,
20-22; Bird 2007a, pp. 66-67, 2013; Ellis 2010; Yates
forthcoming for some attempts to characterise categorical properties.
(Note that hybrid properties--like the property of *being
soluble and round*--are possible (McKitrick 2003b, footnote
9). We'll ignore them.) 


### 2.1 Entailment



What is it about dispositions that sets them apart from categorical
properties? Traditionally it is suggested that ascriptions of
dispositions do, whilst ascriptions of categorical properties do not,
entail certain counterfactual conditionals:



**Entailment.** 
\(F\) is a disposition iff there are an associated stimulus
condition and manifestation such that, necessarily, \(x\)
has \(F\) only if \(x\) would produce the manifestation if
it were in the stimulus condition.




Among the philosophers who have supported *Entailment*, or
something like it, are Carnap (1936-7), Ryle (1949), Goodman
(1954), Quine (1960), Mackie (1973), Prior (1985), and Armstrong,
Martin & Place (1996), Mumford (1998), Choi (2005b, 2008,
2012).



If disposition ascriptions do not entail corresponding counterfactual
conditionals, then *Entailment* is hopeless. Note
that the apparent counterexamples to *SCA* may seem
to show just that. But let's leave this claim aside for the sake of
argument. Still *Entailment* might be disputed on the
ground that ascriptions of dispositions are not unique in this regard.
Mellor (1974) takes an allegedly paradigmatic categorical property,
triangularity, and claimed that if \(x\) is triangular,
then if its corners were correctly counted, the result would be
three. *Entailment* therefore seems to predict that
'triangular' expresses a disposition. And as for
'triangular' so, presumably, for any predicate that might
be thought to express a categorical property.



Mellor's suggestion, though, is liable to the problems of
reverse-finks and maskers. One can easily set up an analogous case to
an example of reverse-finks or maskers that shows that Mellor's
conditional is not entailed by '\(x\) is
triangular': \(x\) is triangular but if its
corners were about to be counted a sorcerer would change its shape so
that the result of counting would not be three. Further, Prior (1982,
1985) argues that if we are to understand 'correctly' in
the antecedent of Mellor's conditional as referring to
the *method* of counting, as opposed to the result of
counting, then his claim is false. For there are possible worlds in
which quirky laws of nature ensure that counting always gives the
wrong result. (Bird (2003, 2009) gives a useful discussion of the
general lessons that should be drawn from the debate between Prior and
Mellor.)



But it might be suggested that these problems for Mellor's claim can
be handled by introducing a *ceteris paribus* clause
in much the same fashion as, as we have seen in
 section 1.5,
 some philosophers do with respect to conventional dispositions. The
suggestion is that the stimulus condition of triangularity is not
simply \(x\)'s corners being correctly counted
but \(x\)'s corners being correctly counted under certain
standard conditions. Although '\(x\) is
triangular' may not entail Mellor's conditional as it stands, it
does entail that if \(x\)'s corners were correctly
counted *under certain standard conditions*, it would give
the result of three, where the standard conditions are understood to
rule out cases where reverse-finks or maskers operate or quirky laws
of nature obtain. Notwithstanding this defence of Mellor's claim,
however, Choi argues that it is still hopeless, to which we will turn
below.


### 2.2 Intrinsic Finks



Choi (2005b) imagines a tricky
triangle \(T\_t\) which has the same intrinsic
properties as an ordinary triangle except that it has
an *intrinsic* property that would cause it to become
rectangular if someone starts to count its corners. What
if \(T\_t\)'s corners were correctly counted under
standard conditions? Given that standard conditions are generally
thought to
involve \(T\_t\)'s *extrinsic* properties
only, \(T\_t\) would become rectangular in virtue
of one of its own intrinsic properties; as a result, it would not
elicit the result of three but the result of four. It is therefore not
true that if \(T\_t\rsquo\text{s}\) corners were correctly
counted under standard conditions the result would be three. But it is
intuitively evident that \(T\_t\) is
triangular. From this Choi concludes that '\(x\) is
triangular' does not even entail the *ceteris
paribus* version of Mellor's conditional.



One might suspect, however, that Choi's thought experiment will
backfire on the ground that we can envision an analogous case for
dispositions: an object \(S\_t\) only differs from a fragile glass in
that the first, not the second, has an *intrinsic* property
that would cause it to lose \(M\) if it were struck, where \(M\) is
the type of microstructure \(S\_t\) has in common with the fragile
glass. \(S\_t\) does not satisfy the counterfactual conditional that it
would break if struck under the standard conditions. But is \(S\_t\)
not supposed to have almost all intrinsic properties in common with a
fragile glass, most importantly, the microstructure \(M\)? This might
lead one to think that \(S\_t\) is fragile, from which it follows that
even the ascription of fragility does *not* entail the
corresponding counterfactual conditional. In response, though, Choi
(2005b, pp. 499-502, 2012) urges that \(S\_t\) is *not*
fragile. He has thus defended (a *ceteris paribus* version of)
*Entailment* from Mellor's objections by
invoking *intrinsically finkish properties*.



Handfield (2008b) gives an insightful angle to Choi's thought
experiment. Let's say that a property putatively considered to be
dispositional is intrinsically finkable or not depending on whether or
not an object can co-instantiate it along with
an *intrinsic* property that would remove it should
the stimulus condition be present. Then Handfield suggests that the
core idea of Choi's thought experiment is that dispositional
properties are not intrinsically finkable but categorical properties
are.



At least some dispositions
are *extrinsically* finkable. Martin's examples can
be understood to show that the dispositional property of being live is
extrinsically finkable. We can readily get a similar result for
categorical properties. Handfield urges, though, that there is a
glaring contrast between dispositional and categorical properties when
we look at intrinsic finks, which is illustrated by Choi's thought
experiment. \(T\_t\) is triangular but it also
has an intrinsic property that would remove its triangularity if its
corners were counted. This property serves as an intrinsic fink to
triangularity. The case of \(S\_t\), however, is
claimed to show that we cannot devise an analogous case for
dispositions, which permits the conclusion that fragility is not
intrinsically finkable--and *mutatis
mutandis* for the possibility of intrinsic reverse-finks,
maskers, and mimickers. This view has been criticised by Clarke (2008,
2010), Fara (2008), Everett (2009), Ashwell (2010), Kittle (2015),
Tugby (2016), and Bird (manuscript), though.



Choi (2012, 2017a, 2017b) addresses some of their criticisms. This
issue is importantly relevant to many other issues such as
Kripke-Wittgenstein rule-following puzzle (Martin & Heil 1998;
Handfield & Bird 2008; Cheng 2010; Schlosser 2011), the principle
of alternate possibilities (Cohen & Handfield 2007), the nature of
desires (Ashwell 2014, 2017), and so on.


## 3. Categoricalism, Dispositionalism, and Laws of Nature



In contemporary metaphysics, a surging number of philosophers express
their allegiance to dispositional essentialism, the position that at
least *some* properties have dispositional essences.
Some of them go beyond this to take a stronger position,
that *all* suitably qualified properties are
essentially dispositional (Popper 1959; Harre 1970;
Harre & Madden 1975; Shoemaker 1980; Mumford 2004; Bird
2005b, 2007a; Chakravartty 2007; Whittle 2008; Tugby 2013, 2014; Yates
forthcoming; For the most up-to-date exposition of this view, see Bird
2016). This position is known as dispositional monism or causal theory
of properties. Alternatively it is simply named
'dispositionalism'. The strongest version of
dispositionalism is pan-dispositionalism which says that all
properties in the broadest sense of 'property' have
dispositional essences. But many philosophers hold a more nuanced
position like Bird's pure power theory which says that all sparse
properties in Lewis (1986)'s sense--or, in Bird's own terms, all
fundamental ontic properties--have dispositional essences.



The dispositionalist holds that the essence of a property \(P\) is
wholly constituted by the nomic or causal roles \(P\) plays--for
short, theoretical roles. Here the nomic role of \(P\) is given in
terms of the Ramsey sentence that we can get from a true and complete
final theory, a sentence that represents the totality of the factual
content of the theory. The causal role of \(P\), on the other hand, is
given in terms of its potential causes and effects. Dispositionalism
thus implies the following transworld identity condition for
properties: properties \(P\) and \(Q\) are identical iff they play the
same theoretical roles. (This identity condition smacks of circularity
since theoretical roles can be plausibly considered as high-order
dispositional properties. This issue is discussed in detail in 
 Appendix.)
Note that the theoretical roles played by a property \(P\) determine
how its instances are disposed to act or react under various
circumstances. On dispositionalism, therefore, \(P\) invariably endows
its instances with the same dispositions, in which sense
dispositionalism implies that properties have dispositional
essences--and only dispositional essences.



The main impetus behind dispositionalism is the discontent
philosophers have with the categoricalist's doctrine that the essence
of a property doesn't have to do with what its instances are disposed
to do under various circumstances. Categoricalism--also known as
categorical monism--is the position that all properties, or at
least all sparse properties are categorical properties, which serves
to underpin the traditional Humean metaphysic that asserts that worlds
can be characterised in terms of their complete histories of
instantiations of *categorical* properties (Lewis
1986, p. 162; Mumford 2006, p. 471; Williams 2011).



A famous argument for categoricalism due to Armstrong (1997, p. 79) is
that dispositions are *Meinongian*--or, in
Handfield's (2005) terms, dispositions are modally inverted. Suppose
that a fragile glass \(x\) doesn't break.
But \(x\) is fragile inasmuch as it would break in
response to being struck under suitable conditions. If
so, \(x\)'s being fragile has within itself, essentially, an
implicit reference to the manifestation, namely, the event of
breaking, that didn't occur. That is, it points to an entirely
*counterfactual* state of affair, in which sense the
property of fragility is at least partly 'hypothetical'.
Armstrong takes it that this consequence is a version of
Meinongianism, a metaphysical position that accepts an overly generous
ontology including non-existent entities, which he finds obnoxious
(see Handfield 2008a for an attempt to get around this objection).
Armstrong goes on to offer what he calls an irenic or soft
deflationist doctrine of dispositional properties. On this view, we
can account for the truth-makers of disposition ascriptions in terms
of categorical properties and laws of nature. Thus understood, to say
that \(x\) is fragile is not to ascribe a real property
to \(x\). Rather, it is an abbreviated way of saying that,
given laws of nature, from \(x\)'s being struck, we can
infer that \(x\) would break. On Armstrong's view, we do not
use dispositional terms to describe irreducibly dispositional states
of affairs. Rather, they are merely convenient ways of talking
about *categorical properties*.



Armstrong implicitly assumes that categorical properties are
non-Meinongian. This brings under the spotlight the question of how to
characterise the essences of categorical properties in a way that
renders them non-Meinongian. Towards this end, most categoricalists
including Armstrong subscribe to *quidditism*, according
to which the essence of a property is constituted by its internal or
self-contained nature, that is, what is called *quiddity*,
that is only contingently related to the specific theoretical roles it
plays (Armstrong 1989, 1997; Lewis 2009). (Despite this move,
Handfield (2005) criticises, Armstrong is still susceptible to the
'Meinongianism objection' as his nomic necessitation
relation \(N\) is constituted by a relation
to *counterfactual* states of affairs.) Armstrong
(1997, p. 80) thus says, 'properties are self-contained things,
keeping themselves to themselves, not pointing beyond themselves to
further effects brought about in virtue of such properties'.
Then what exactly is this internal or self-contained nature? Given
that theoretical roles are ruled out as being merely contingently
related to it, there seems to be very little to be said about it. Thus
Black (2000, p. 91) says that, according to Lewis who accepts
quidditism, 'Just about all there is to a Humean fundamental
quality is its identity with itself and its distinctness from other
qualities'. On quidditism, the essence of a property
puts *no constraint whatsoever* on how its instances
are disposed to act or react under various circumstances. This is why
quidditism goes along with categoricalism which asserts that
properties have no dispositional essences.



Quidditism is to properties what haecceitism is to individuals.
Haecceitism famously implies a theory
of *primitive* identity of individuals across
possible worlds. Likewise, quidditism implies a theory
of *primitive* transworld identity of properties
which asserts that two properties are identical iff they are
quiddistically the same, regardless of their theoretical roles (Black
2000; Whittle 2006; Lewis 2009). This being the case, a property could
confer upon its instances completely different causal or nomic powers
than it actually does but nonetheless continue to be the same property
as it actually is so long as it remains quiddistically the same. The
causal or nomic profile of a property is thus a merely contingent
matter. (Schaffer (2005) points out that this
'contingentism' is not necessarily paired with quidditism:
'anti-quiddistic contingentism' is a respectable
position.)



Quidditism therefore implies that laws of nature
are *metaphysically contingent*, for, for any class of
properties, there seems to be nothing standing in the way of either
the possibility that they are bound up with each other by laws of
nature or the possibility that they are not related at all to each
other by any laws of nature. A consequence of quidditism is therefore
that although, for instance, colour properties and mass properties are
not actually linked with each other by any laws, they could have been
so linked. Laws of nature are therefore a contingent matter. Some
quidditists may go further to say that laws of nature are a type of
regularity among property instances (Ramsey 1978; Lewis 1973; Earman
1984). Others may suggest that laws of nature are nomic necessitation
relations between universals (Armstrong 1983; Dretske 1977; Tooley
1977).



Dispositionalism is a stark contrast to categoricalism, maintaining
that all properties have dispositional essences. The dispositionalist
charges that the categoricalist's appeal to the internal or
self-contained nature of a property as its essence
is *unintelligible* unless it is somehow related to
the causal or nomic powers of its instances. On dispositionalism, as
noted earlier, a given property endows all of its instances with the
same dispositions, no matter what circumstances they are situated in.
Dispositionalism then necessitates a diametrically opposing view of
laws of nature to the one necessitated by categoricalism--more
to the point, the one necessitated by quidditism. Because the property
of being negatively charged has the essence characterised in terms of
the disposition to attract positively charged particles and repel
negatively charged particles, on dispositionalism, all negatively
charged particles are necessarily so disposed. This entails that
Coulomb's law, which describes how charged particles interact with one
another, is *metaphysically necessary* (see Corry 2011 for
a criticism of this reasoning). In general, the dispositionalist
typically maintains what Hildebrand (2014) calls 'Descriptive
Non-Humeanism', the view that laws of nature are just universal
descriptions of dispositional essences of properties; and they are
metaphysically necessary because their truth is ensured by the
dispositional essences of relevant properties in all the possible
worlds where those relevant properties exist. (This point is made by
Swoyer (1982), Ellis (2001), Kistler (2002), and Bird (2005a, 2007a);
see Mumford 2004 for the claim that dispositionalism obviates the need
for laws and see Bird 2007a, chapter 9 for a criticism of this claim;
see Chalmers 1999 and Fine 2002 for the claim that some of natural
necessities, e.g., conservation laws, cannot be accounted for by
dispositionalism.) Dispositionalism is hoped to provide a
comprehensive and unified metaphysical grounding for natural
modalities in general that may serve as an alternative to Humeanism.
For some attempts at it, see Williams & Borghini 2008, Martin
2008, Jacobs 2010. Handfield (2008a) does not take dispositionalism
and Humeanism as incompatible and explores the possibility of
combining them to construct what he calls 'Humean
dispositionalism'. Simpson (2017), however, criticises this combination as being half-baked.



Categoricalism and dispositionalism are two extremes of a large
spectrum of possible positions on the essences of properties. For
instance, philosophers like Swoyer (1982), Ellis & Lierse (1994),
Ellis (1999, 2001, 2010), and Molnar (2003) maintain that some
properties are essentially dispositional but others, most notably
spatio-temporal properties, are not, in which sense they are
dispositional essentialists but not dispositionalists. Another
alternative that has lately gained considerable ground is what is
called the 'powerful qualities view'. The view is that
every property is in some sense both dispositional and qualitative
(Here 'qualitative' is used interchangeably with
'categorical'). It was pioneered by Martin and Heil
(Armstrong, Martin & Place 1996; Martin 1997; Martin & Heil
1999; Heil 2003, 2005) and further developed by Engelhard (2010),
Jacobs (2011), Ingthorsson (2013), Carruth (2016), and Taylor
(2018a, 2018b). A big challenge for this view is to
give a satisfactory account of exactly how one and the same property
is both dispositional and qualitative (Armstrong 2005). A popular
response to this challenge is that "the qualitative and
dispositional are identical with one another and with the unitary
intrinsic property itself" (Martin 2008, p. 65). However, given
that there is a strong inclination to think that the dispositional
nature of a property is distinct from, if not incompatible with, its
qualitative nature, there is no doubt that more details are needed in
order to render this view a fully respectable competitor. Some
attempts at it have been made by Jacobs (2011), Ingthorsson (2013),
and Taylor (2018b).



Notwithstanding this profusion of possible positions to be taken,
however, categoricalism and dispositionalism have been the focus of
discussion in the literature. For some of the criticisms and arguments
dispositionalists and categoricalists have traded, see the 



Appendix on Quiddistically Different Worlds, Irremediable Ignorance, and Regress of Powers.
 


## 4. Dispositions and Categorical Bases



The causal basis for \(x\)'s disposition is something
like \(x\)'s microstructural property that is or would be
causally responsible for the manifestation of that disposition. It
will be helpful to have in hand a characterisation of 'causal
basis' that is more perspicuous than this. In their seminal
paper on dispositions, Prior, Pargetter & Jackson (1982) offer the
following definition (p. 251):



**PPJ.** 
A causal basis for disposition \(D\) is the property or
property-complex that, together with the characteristic stimulus
of \(D\), is a causally operative sufficient condition for the
characteristic manifestation of \(D\) in the case of
"surefire" dispositions, and in the case of probabilistic
dispositions is causally sufficient for the relevant chance of the
manifestation.



We will not here consider cases of probabilistic dispositions; the
'surefire' or deterministic cases are difficult enough. A
clarification is needed of the concept of causally operative
sufficient condition. One thing we can say for sure about it is that a
condition is causally operative *sufficient* for some
effect only if, given the laws of nature, whenever the condition is
present it is causally necessary that the effect
occurs. *PPJ* then entails the following account
of causal basis: a causal basis for \(D\) is a property
or property-complex \(P\) such that, given the laws of
nature, whenever an
object \(x\) has \(P\) and undergoes the
characteristic stimulus of \(D\), it is causally necessary
that \(x\) exhibits the characteristic manifestation
of \(D\). Nolan (2015) suggests that a link between the
characteristic stimulus and manifestation of \(D\) doesn't need
to be a causal one, and then criticises *PPJ* on the ground
that it presupposes such a causal link. (For another criticism
of *PPJ*, see Contessa 2012.)



*PPJ* is not the only way to characterise the notion of
causal basis. Lewis (1997), for example, derives an alternative
characterisation of causal basis from *RCA*, as pointed
out by Hauska (2008a). The causal basis for \(D\) is
then approximately defined as an intrinsic
property \(P\) that would cause \(x\) to
manifest \(D\) if \(x\) were to be
exposed to the stimulus condition and, at the same
time, \(x\) were to retain \(P\) for a
sufficient time. (For still alternative characterisations of causal
basis, see Mackie 1977, Johnston 1992, McKitrick 2003b, and Molnar
2003.)



Note that *PPJ* and Lewis's characterisation both
leave it an open question whether the causal bases for a disposition
need be categorical properties, or instead a disposition might have a
disposition as a causal basis. Also it leaves it an open question
whether a disposition could serve as a causal basis for itself or not.
These open questions are the topic of the upcoming sections.


### 4.1 The Possibility of Bare Dispositions



Based dispositions are dispositions with causal bases that
are *distinct* from the dispositions themselves.
Assuming that the glass's microstructural property is a causal basis
for and is distinct from its fragility, its fragility is a based
disposition. As noted earlier, the possibility that a disposition
serves as a causal basis for *itself* is not ruled
out by the definitions of causal basis like *PPJ* or
Lewis's, in which case, the disposition is not a based disposition as
it is not *distinct* from its causal basis. The
requirement that a disposition be distinct from its causal basis
should be carefully understood: it should not be interpreted to rule
out causal bases that are only *contingently* identical to
the corresponding dispositions. Based dispositions are dispositions
with causal bases that are
not *necessarily* identical to the dispositions
themselves, in which sense they have distinct causal bases. When a
disposition serves as a causal basis for itself, it is necessarily
identical to its causal basis, which entails that it is not a based
disposition. It might be thought, though, that a based disposition is
contingently identical to its causal basis. In fact, Armstrong
(Armstrong, Martin & Place 1996) is well known for his claim that
all based dispositions are contingently identical to their bases (cf.
see
 section 4.2
 below). Bare dispositions
are *baseless* dispositions, which means that they
are dispositions with no distinct causal bases (McKitrick 2003b). See
Johnston 1992, Smith & Stoljar 1998, and Williams 2011 for
different definitions of bare disposition.



The categoricalist maintains it is categorical properties that we
truly attribute to \(x\) when we apparently talk
about \(x\)'s dispositions. What are those categorical
properties? To this question, the categoricalist typically suggests
that they are *categorical causal bases*, which rests on
the assumption that all dispositions (more precisely, all of what we
apparently consider as dispositions) must have categorical properties
as causal bases. This is why the categoricalist is typically inclined
to deny the possibility of bare dispositions. Conversely, the
dispositionalist is not similarly pressed to say that dispositions
must have causal bases, or at least, that all dispositions must have
distinct causal bases. For this reason, some dispositionalists leave
it an open question whether bare dispositions are possible or not but
most of them, finding unattractive the idea of dispositions all the
way down, go further to affirm the possibility of bare dispositions
(McKitrick 2003b; Mumford 2006; Ellis 2001, 2002; Molnar 1999, 2003).
Investigating the possibility of bare dispositions thus bears major
significance for the debate between dispositionalism and
categoricalism.



Prior et al. provide one important argument for the thesis that,
necessarily, every disposition has a causal basis--a thesis they
label the 'Causal Thesis'. Putting the case of
probabilistic dispositions aside, they consider an
object \(A\) that is subject to knocking in a
deterministic world. They argue (pp. 251-252):



> 
> 
> [I]t will be either determined that \(A\) breaks, or
> that \(A\) does not break. In the latter case
> clearly \(A\) is not fragile. In the former there will be a
> causally sufficient antecedent condition operative in producing the
> breaking--that follows from Determinism. Hence
> if \(A\) is fragile and Determinism is true, there must
> be a causal basis.
> 
> 
> 



This argument itself, if successful, doesn't show that dispositions
must have *distinct* causal bases. It is consistent
with the causal basis for a disposition being identical with the
disposition itself. As we will see in
 section 4.2,
 however, Prior et al. do have at hand separate arguments for the
thesis that dispositions are distinct from their causal bases. Taken
together, these arguments will show the impossibility of bare
dispositions. (See Hauska 2008a and Nolan 2015 for a criticism of
Prior et al.'s argument.)



Smith and Stoljar (1998) argue that the proponent of the possibility
of bare dispositions is committed to there being relations of
'bare similarity' holding between possible worlds, which
they take as unacceptable. McKitrick (2003b) argues in response,
first, that Smith and Stoljar do not succeed in showing that the
commitment to bare similarity follows from the possibility of bare
dispositions, and, second, that even if it did then this would not be
nearly as problematic as they take it to be. If one has already
accepted that there might be bare dispositions then, McKitrick
suggests, one should not be uncomfortable with the idea that there
could be 'barely similar' possible worlds.



So much for arguments in favour of the impossibility of bare
dispositions. A *strong* argument for the possibility
of bare dispositions begins with the thought that fundamental
properties like spin, electric charge, etc., are all dispositional.
This observation is put together with the assumption that, to the
extent to which subatomic particles like leptons and quarks are
fundamental, they cannot have any constituting parts. This assumption
seems to be supported by experimental results in physics, showing that
fundamental particles behave like point-like, structureless particles
(Molnar 1999, 2003). But it entails that their dispositions cannot be
grounded by the properties of their constituting parts. This seems to
lead to the conclusion that dispositional properties of fundamental
particles are bare dispositions, lacking any distinct causal bases
(Harre & Madden 1975; Blackburn 1990; Ellis & Lierse
1994; Ellis 2001, 2002; Molnar 1999, 2003; McKitrick 2003b; the most
powerful elaboration of this argument is given by Mumford 2006).



This argument is meant to prove *more than* needed
for the refutation of categoricalism. Given that categoricalism
entails the impossibility of bare dispositions, establishing the mere
possibility of bare dispositions will suffice for refuting
categoricalism. But the argument at hand, if successful, would
demonstrate that fundamental properties are bare dispositions,
entailing that bare dispositions do actually exist.



What should we make of this argument? Williams (2009, 2011) conducts
an instructive discussion of it, where he, following Ellis and Lierse,
labels it the 'argument from science'--Mumford (2006)
names it the 'ungrounded argument'. He points out that it
is 'not just one argument, but a small, close-knit family of
arguments'. The specific argument we presented earlier is most
similar to what he calls the indirect 'structureless'
version, which he takes as the most common among versions of the
argument from science. Williams's worry about it is that what follows
from the reasonable assumption that fundamental particles do not have
constituting parts is not that their dispositions are in no way
grounded but that their dispositions are not grounded via
compositional structure. On his view, it is still an open possibility
to the categoricalist that their dispositions are grounded via
*supervenient structure*, meaning that dispositions of a
subatomic particle supervene upon categorical properties of the
particle *itself*.



In response, it might be thought that subatomic particles
are *entirely* characterised in terms of dispositions
like spin and electric charge, and therefore that they possess no
categorical properties on which their dispositions would supervene, in
which case the possibility of grounding via supervenient structure is
blocked. Williams (2009, p. 13) retorts, though, that the reason why
physicists speak only in terms of dispositions when they describe
subatomic particles is merely that the *only* means
they have to investigate subatomic particles is to 'poke and
prod at them with bombardments, and see how they react' (For a
similar point, see Strawson 1980; Blackburn 1990; Jackson 1998;
Langton 1998; Hawthorne 2002; Lewis 2009). But this is not to say that
they, as a matter of fact, have no categorical properties at all. In
fact, we have, Williams continues to argue, good metaphysical reasons
for attributing categorical properties to subatomic particles.



We have thus far seen that there is an ongoing debate regarding the
thesis that *all* dispositions have distinct causal
bases. But philosophers are in wide agreement with respect to a weaker
thesis that at least *some* dispositions have
distinct causal bases. This weak thesis, however, already raises an
interesting question concerning
the *relation* between dispositions and their causal
bases, to which we turn in the next section.


### 4.2 The Relation between Dispositions and Their Bases



Views about the relation between dispositions and their causal bases
mirror views about the relation between mental and physical
properties. Armstrong, Martin & Place (1996) and Mackie (1973,
1977) defend a 'type-identity theory' according to which
any disposition is identical with its causal basis. Mumford (1998)
defends a 'token-identity theory' according to which any
instance of a disposition is identical with an instance of its causal
basis. Prior--together with Pargetter and Jackson--defends a
'functionalist theory' according to which a disposition is
a second-order property of having some causal basis or other. There
are other views too, but we will confine discussion here to the three
mentioned above.



Armstrong (Armstrong, Martin & Place 1996, chapter 3) puts forward
one argument for the identity of dispositions with their causal bases
that basically goes as follows: since dispositions are by definition
properties that play certain causal roles, and since in fact their
causal bases are what play those roles, it follows that dispositions
are in fact identical with their causal bases. Armstrong claims that
his identification of dispositions with their causal bases is a
'contingent identification' (Armstrong et al. 1996, p. 39): *As a matter of fact* the property that
plays the brittleness role is such-and-such, but it might have been a
different property that played that role; if so, brittleness would
have been identical with that different property. This feature of
Armstrong's view exposes it to Prior et al.'s (1982) argument from
rigid designation. Following Kripke, Prior et al. take names of
properties to be 'rigid designators', referring to the
same property in every possible world (in which that property exists).
As Kripke (1972) demonstrates,
if \(a\) and \(b\) are rigid designators
then the identity
statement \(a = b\) is *necessarily* true
if it is true at all. So on the assumption that, for example,
'brittleness' and 'microstructural property
so-and-so' are rigid designators, the possibility that the
causal basis for brittleness might have been something other than
microstructural property so-and-so shows that brittleness is not
identical with microstructural property so-and-so. (See McKitrick
2003b for a reply to this argument. For additional arguments against
Armstrong's view, see Prior et al. 1982 and Prior 1985; for
discussions on them, see Mumford 1998, chapter 5 and McKitrick
2003b.)



Opposing the identity of dispositions with their causal bases, Prior
et al. present arguments for what they call the 'Distinctness
Thesis'. One of them is the argument from rigid designation,
which we have just discussed. Another springs from the possibility of
multiple realization of dispositions. Different fragile objects, for
example, have different causal bases--some are fragile in virtue
of their irregular atomic structure, some are fragile in virtue of
their weak intermolecular bonding. This seems to serve as evidence for
the Distinctness Thesis. Why? If dispositions were identified with
their causal bases, we will end up having to say that diverse causal
bases of fragility are identical to each other. But they
are, *ex hypothesi*, distinct from each other. And so
Prior et al. argue that the multiple realizability of dispositions
provides a *reductio* basis for the Distinctness
Thesis.



Mumford (1998, chapter 7) endorses this argument when it is construed
as an argument against the 'type-type' identification of
dispositions with their bases that Armstrong defends. But Mumford
takes a strategy familiar from the philosophy of mind and maintains
that Prior et al.'s argument does not defeat his own
'token-token' identification. According to Mumford,
although in general dispositions are not identical with their bases,
each *instance* of a disposition is identical with an
*instance* of its causal basis. Anticipating Mumford's
response, Prior (1985) complains that it is not at all clear what can
be meant by 'property instance' if, as Mumford maintains,
an object's instance of property \(A\) can be the very
same thing as its instance of property \(B\), even though
property \(A\) is not the same as
property \(B\). Even if we grant the intelligibility of such
a notion of property instance, however, might not the very same
argument from rigid designation show that instances of dispositions
cannot be identical with instances of their bases, any more than
dispositions themselves can be identical with their bases? Such would
seem to be the appropriate lesson to draw from the fact that Kripke's
original version of the argument, aimed against identity theories in
philosophy of mind, applies as much to token-token as to type-type
versions of the identity theory. Mumford disagrees (p. 157), although
he says little to substantiate his disagreement. (See Rives 2005 for
another objection to Mumford.)



In the preceding paragraphs, we have canvassed Prior et al.'s
arguments for their Distinctness Thesis. Using these arguments as a
stepping stone, Prior (1985, chapter 7) and Jackson (1998) advance the
functionalist view that disposition \(D\) is a
second-order property, the property of having some first-order
property or other that plays the causal role corresponding
to \(D\). It seems to be a consequence of this view that
dispositions do *no* causal work (see
 section 6
 below). For if having, say, the property of fragility is a matter of
having a *first*-order property that plays the causal role
associated with fragility, then it would seem that it is this
first-order property, not the second-order property, that does all
causal work. It would seem, then, that the functionalist view is open
to the objection that it predicts dispositions to be 'causally
superfluous' in a way that, intuitively, they are not. (See
Mumford 1998; Martin & Heil 1999; Heil 2003, 2005 for this
objection, and see
 section 6
 below for further discussion.)


## 5. The Intrinsicness of Dispositions



The Intrinsic Dispositions Thesis (for short, IDT), the thesis that
dispositions are intrinsic properties of their bearers, has been
routinely accepted by many philosophers like Harre (1970),
Armstrong (1973), Mellor (1974), Mackie (1977), Bird (1998), Molnar
(2003), Choi (2005b), and Menzies (2009). Accepting it, Lewis (1997)
says, 'if two things (actual or merely possible) are exact
intrinsic duplicates (and if they are subject to the same laws of
nature) then they are disposed alike' (p. 147). Lewis's
qualification about the laws of nature is important, at least for
those who take the laws to be contingent, for without it IDT is
scarcely plausible. If the laws are contingent then a fragile glass
has intrinsic duplicates that are not disposed to break when struck.
Some of them will inhabit possible worlds whose laws of nature
determine that, if struck, they would experience a gentle deformation
temporarily and then regain its original shape. IDT, therefore, should
be understood as the thesis that within any sphere of worlds with the
same laws of nature, any pair of objects with the same intrinsic
properties will have the same dispositions. (For discussion of the
precise meaning of the intrinsicness of dispositions, see Langton
& Lewis 1998; Choi 2009; and Handfield 2009.)



Widely accepted as it is, however, IDT is not obviously true.
Shoemaker (1980) considers a key's disposition to open his front door
and points out that it could lose this disposition without undergoing
any intrinsic change, for example, by the lock on his door being
replaced by one of a different kind. It would seem, then, that the
disposition to open Shoemaker's front door is not an intrinsic
property of the key, and so IDT is false.



This apparent counterexample can be resisted, however. The only
relevant disposition possessed by Shoemaker's key, it might be
insisted, is the disposition to open locks of a
certain *type*--the type of lock that is currently on
Shoemaker's front door. Since a change in the lock will not cause the
key to lose this disposition, it is an intrinsic disposition--or
at least the present example does not show that it is not intrinsic.
According to this response, the predicate 'disposed to open
Shoemaker's front door' either fails to express a genuine
property at all--this is Shoemaker's view--or else it
somehow manages to express the intrinsic disposition to open locks of
a certain type (Molnar 2003). McKitrick (2003a), however, argues that
this response fails. She goes further to argue that there are indeed
many cases of extrinsic dispositions, listing as
examples *weight* (a case borrowed from Yablo
1999), *vulnerability*, *visibility* and *recognizability*.
In light of these examples, it seems hard to dismiss the
counterexamples to IDT as concerning spurious dispositions.



It is worth recalling that Lewis (1997) assumed IDT with a view to
bolstering Martin's counterexamples to *SCA*. But it has
come to light that IDT is false. Does this necessitate that Lewis
fails to bolster Martin's counterexamples? Choi (2009) answers this
question in the affirmative.


## 6. The Causal Efficacy of Dispositions



Some philosophers have said that dispositions
are *not* causes of, or causally explanatory of,
their manifestations. Why? Their thought can be encapsulated by
Moliere famous quip, in *Le Malade Imaginaire*,
that a philosopher might explain why opium puts people to sleep by
mentioning the fact that it has a 'dormitive virtue'. The
point, of course, is that this is no explanation or, if it is, it is
not a good explanation. To have a dormitive virtue, it seems, is just
to have a property that puts people to sleep, and that fact tells us
only a little, if anything, about *why* substances
with that property put people to sleep. In general, \(x\)'s
possession of a disposition \(D\)
*conceptually* necessitates \(x\)'s manifesting
\(D\) under a suitable condition, and conceptual necessitation is
not a kind of causal or explanatory connection. This is what McKitrick
(2004, 2005) names the 'analyticity argument' for the
causal inefficacy of dispositions. Arguments of this kind have been
brought forth by Mackie (1973, 1977), Armstrong (1968), Block (1990),
and Jackson (1995, 1996).



There is another type of argument. Prior et al. (1982) argue that the
causal inefficacy of dispositions is a consequence of the Causal
Thesis and the Distinctness Thesis combined (see
 section 4
 above):



> 
> 
> By the Causal Thesis, any disposition (and thus fragility) must have a
> causal basis. This causal basis is a sufficient causal explanation of
> the breaking *as far as the properties of the object are
> concerned*. But then there is nothing left for any other
> properties of the object to do. By the Distinctness Thesis the
> disposition is one of these *other* properties, ergo
> the disposition does nothing. (p. 255)
> 
> 
> 



This argument is akin to 'exclusion arguments' advanced
by, for instance, Block (1990) and Kim (1990, 1998) to deny the causal
efficacy of mental properties. See Yablo 1992 for an objection to the
exclusion argument, to the effect that a mental event is 'better
qualified than its physical basis for the role of cause' (p.
279).



Prior et al. point out that their argument assumes that a disposition
cannot be an *overdetermining* cause of its manifestation,
more generally, that no event can have two 'operative'
sufficient conditions (see also Jackson 1998, p. 202).
Since, *ex hypothesi*, it is the causal basis for the
disposition that is the *operative* sufficient
condition for its manifestation, the disposition itself, even though
its possession is sufficient in the circumstances for the
manifestation, is an *inoperative* sufficient condition,
and so is not a cause. Schaffer (2003), however, argues that cases of
overdetermining causes in Prior et al.'s sense are not just possible
but, as a matter of fact, routine. In his view, they must be modeled
after ubiquitous cases of quantitative overdetermination where
'the cause is decomposable into distinct and independently
sufficient parts': when one big round rock hits a window, it has
two hemispheres that quantitatively overdetermine the breaking of the
window. If Schaffer is right, then Prior et al.'s argument for the
causal inefficacy of dispositions is defused. (See Rives 2005 for a
different formulation of the argument that doesn't assume that a
disposition cannot be an *overdetermining* cause of
its manifestation.)



We have surveyed two salient arguments for the causal inefficacy of
dispositions. Note that they, to be successful, would have to be
accompanied by an account of what causal efficacy *is*,
and the large literature on causal efficacy attests to the difficulty
of complying with this demand. McKitrick (2005) surveys several of the
existing accounts of causal efficacy--or, in her terms, causal
relevance--and argues that the most plausible of these give us no
clear reason for thinking that dispositions are causally irrelevant to
their manifestations.