ABBREVIATIONS AND TYPOGRAPHICAL CONVENTIONS

THE following conventions are adopted throughout:
Concepts are construed as mental particulars. Names of concepts are
written in capitals. Thus, ‘RED’ names the concept that expresses redness
or the property of being red. Formulas in capitals are not, in general,
structural descriptions of the concepts they denote. See Chapter 3, n. 1.
Names of English expressions appear in single quotes. Thus ‘‘red’’ is
the name of the homophonic English word.
Names of semantic values of words and concepts are written in italics.
Thus ‘RED expresses the property of being red’ and ‘ ‘Red’ expresses the
property of being red ’ are both true.
The following abbreviations are used frequently (especially in Chapters
6 and 7).
RTM: The representational theory of the mind
IRS: Informational role semantics
MOP: Mode of presentation
MR: Mental representation
IA: Informational atomism
SA: The standard argument (for radical concept innateness)
SIA: Supplemented informational atomism (= IA plus a locking theory
of concept possession)
d/D problem: The doorknob/DOORKNOB problem.
ABBREVIATIONS AND
TYPOGRAPHICAL CONVENTIONS
MY topic is what concepts are. Since I’m interested in that question
primarily as it arises in the context of ‘representational’ theories of mind
(RTMs), a natural way to get started would be for me to tell you about
RTMs and about how they raise the question what concepts are. I could
then set out my answer, and you could tell me, by return, what you think
is wrong with it. The ensuing discussion would be abstract and theory
laden, no doubt; but, with any luck, philosophically innocent.
That is, in fact, pretty much the course that I propose to follow. But, for
better or for worse, in the present climate of philosophical opinion it’s
perhaps not possible just to plunge in and do so. RTMs have all sorts of
problems, both of substance and of form. Many of you may suppose the
whole project of trying to construct one is hopelessly wrong-headed; if it
is, then who cares what RTMs say about concepts? So I guess I owe you
some sort of general argument that the project isn’t hopelessly wrongheaded.
But I seem to have grown old writing books defending RTMs; it occurs
to me that if I were to stop writing books defending RTMs, perhaps I
would stop growing old. So I think I’ll tell you a joke instead. It’s an old
joke, as befits my telling it.
Old joke: Once upon a time a disciple went to his guru and said: ‘Guru,
what is life?’ To which the Guru replies, after much thinking, ‘My Son,
life is like a fountain.’The disciple is outraged. ‘Is that the best that you can
do? Is that what you call wisdom?’ ‘All right,’ says the guru; ‘don’t get
excited. So maybe it’s not like a fountain.’
That’s the end of the joke, but it’s not the end of the story. The guru
noticed that taking this line was losing him clients, and gurus have to eat.

Philosophical Introduction: The Background Theory

MY topic is what concepts are. Since I’m interested in that question
primarily as it arises in the context of ‘representational’ theories of mind
(RTMs), a natural way to get started would be for me to tell you about
RTMs and about how they raise the question what concepts are. I could
then set out my answer, and you could tell me, by return, what you think
is wrong with it. The ensuing discussion would be abstract and theory
laden, no doubt; but, with any luck, philosophically innocent.
That is, in fact, pretty much the course that I propose to follow. But, for
better or for worse, in the present climate of philosophical opinion it’s
perhaps not possible just to plunge in and do so. RTMs have all sorts of
problems, both of substance and of form. Many of you may suppose the
whole project of trying to construct one is hopelessly wrong-headed; if it
is, then who cares what RTMs say about concepts? So I guess I owe you
some sort of general argument that the project isn’t hopelessly wrongheaded.
But I seem to have grown old writing books defending RTMs; it occurs
to me that if I were to stop writing books defending RTMs, perhaps I
would stop growing old. So I think I’ll tell you a joke instead. It’s an old
joke, as befits my telling it.
Old joke: Once upon a time a disciple went to his guru and said: ‘Guru,
what is life?’ To which the Guru replies, after much thinking, ‘My Son,
life is like a fountain.’The disciple is outraged. ‘Is that the best that you can
do? Is that what you call wisdom?’ ‘All right,’ says the guru; ‘don’t get
excited. So maybe it’s not like a fountain.’
That’s the end of the joke, but it’s not the end of the story. The guru
noticed that taking this line was losing him clients, and gurus have to eat.
1
Philosophical Introduction: The
Background Theory
Needless to say, this rather baroque belief system gave rise to incredibly
complicated explanations by the tribal elders . . .
—Will Self
So the next time a disciple asked him: ‘Guru, what is life?’ his answer was:
‘My Son, I cannot tell you.’ ‘Why can’t you?’ the disciple wanted to know.
‘Because,’ the guru said, ‘the question “What is having a life?” is logically
prior.’ ‘Gee,’ said the disciple, ‘that’s pretty interesting’; and he signed on
for the whole term.
I’m not going to launch a full-dress defence of RTM; but I do want to
start with a little methodological stuff about whether having a concept is
logically prior to being a concept, and what difference, if any, that makes
to theorizing about mental representation.
It’s a general truth that if you know what an X is, then you also know
what it is to have an X. And ditto the other way around. This applies to
concepts in particular: the question what they are and the question what
it is to have them are logically linked; if you commit yourself on one, you
are thereby committed, willy nilly, on the other. Suppose, for example, that
your theory is that concepts are pumpkins. Very well then, it will have to
be a part of your theory that having a concept is having a pumpkin. And,
conversely: if your theory is that having a concept is having a pumpkin,
then it will have to be a part of your theory that pumpkins are what
concepts are. I suppose this all to be truistic.
Now, until quite recently (until this century, anyhow) practically
everybody took it practically for granted that the explanation of concept
possession should be parasitic on the explanation of concept individuation.
First you say what it is for something to be the concept X—you give the
concept’s ‘identity conditions’—and then having the concept X is just
having whatever the concept X turns out to be. But the philosophical
fashions have changed. Almost without exception, current theories about
concepts reverse the classical direction of analysis. Their substance lies in
what they say about the conditions for having concept X, and it’s the story
about being concept X that they treat as derivative. Concept X is just:
whatever it is that having the concept X consists in having. Moreover, the
new consensus is that you really must take things in that order; the
sanctions incurred if you go the other way round are said to be terrific.
(Similarly, mutatis mutandis for being the meaning of a word vs. knowing the
meaning of a word. Here and elsewhere, I propose to move back and forth
pretty freely between concepts and word meanings; however it may turn
out in the long run, for purposes of the present investigation word
meanings just are concepts.)
You might reasonably wonder how there possibly could be this stark
methodological asymmetry. We’ve just been seeing that the link between
‘is an X’ and ‘has an X’ is conceptual; fix one and you thereby fix the
other. How, then, could there be an issue of principle about which you
should start with? The answer is that when philosophers take a strong line
2 Philosophical Introduction
on a methodological issue there’s almost sure to be a metaphysical subtext.
The present case is not an exception.
On the one side, people who start in the traditional way by asking ‘What
are concepts?’ generally hold to a traditional metaphysics according to
which a concept is a kind of mental particular. I hope that this idea will
get clearer and clearer as we go along. Suffice it, for now, that the thesis
that concepts are mental particulars is intended to imply that having a
concept is constituted by having a mental particular, and hence to exclude
the thesis that having a concept is, in any interesting sense, constituted by
having mental traits or capacities.1 You may say, if you like, that having
concept X is having the ability to think about Xs (or better, that having the
concept X is being able to think about Xs ‘as such’). But, though that’s true
enough, it doesn’t alter the metaphysical situation as traditionally
conceived. For thinking about Xs consists in having thoughts about Xs,
and thoughts are supposed to be mental particulars too.
On the other side, people who start with ‘What is concept possession?’
generally have some sort of Pragmatism in mind as the answer. Having a
concept is a matter of what you are able to do, it’s some kind of epistemic
‘know how’. Maybe having the concept X comes to something like being
reliably able to recognize Xs and/or being reliably able to draw sound inferences
about Xness.2 In any case, an account that renders having concepts
as having capacities is intended to preclude an account that renders
concepts as species of mental particulars: capacities aren’t kinds of things;
a fortiori, they aren’t kinds of mental things.
So, to repeat, the methodological doctrine that concept possession is
logically prior to concept individuation frequently manifests a preference
The Background Theory 3
1 I want explicitly to note what I’ve come to think of as a cardinal source of confusion
in this area. If concept tokens are mental particulars, then having a concept is being in a
relation to a mental particular. This truism about the possession conditions for concepts
continues to hold whatever doctrine you may embrace about how concepts tokens get
assigned to concept types. Suppose Jones’s TIGER-concept is a mental token that plays a
certain (e.g. causal) role in his mental life. That is quite compatible with supposing that
what makes it a token of the type TIGER-concept (rather than a token of the type
MOUSE-concept; or not a token of a concept type at all) is something dispositional; viz.
the dispositional properties of the token (as opposed, say, to its weight or colour or electric
charge).
The discussion currently running in the text concerns the relation between theories about
the ontological status of concepts and theories about what it is to have a concept. Later, and
at length, we’ll consider the quite different question how concept tokens are typed.
2 Earlier, less sophisticated versions of the view that the metaphysics of concepts is
parasitic on the metaphysics of concept possession were generally not merely pragmatist but
also behaviourist: they contemplated reducing concept possession to a capacity for
responding selectively. The cognitive revolutions in psychology and the philosophy of mind
gagged on behaviourism, but never doubted that concepts are some sort of capacities or
other. A classic case of getting off lightly by pleading to the lesser charge.
for an ontology of mental dispositions rather than an ontology of mental
particulars. This sort of situation will be familiar to old hands; proposing
dispositional analyses in aid of ontological reductions is the method of
critical philosophy that Empiricism taught us. If you are down on cats,
reduce them to permanent possibilities of sensation. If you are down on
electrons and protons, reduce them to permanent possibilities of
experimental outcomes. And so on. There is, however, a salient difference
between reductionism about cats and reductionism about concepts:
perhaps some people think that they ought to think that cats are constructs
out of possible experiences, but surely nobody actually does think so; one
tolerates a little mauvaise foi in metaphysics. Apparently, however, lots of
people do think that concepts are constructs out of mental (specifically
epistemic) capacities. In consequence, and this is a consideration that I
take quite seriously, whereas nobody builds biological theories on the
assumption that cats are sensations, much of our current cognitive science,
and practically all of our current philosophy of mind, is built on the
assumption that concepts are capacities. If that assumption is wrong, very
radical revisions are going to be called for. So, at least, I’ll argue.
To sum up so far: it’s entirely plausible that a theory of what concepts
are must likewise answer the question ‘What is it to have a concept?’ and,
mutatis mutandis, that a theory of meaning must answer the question
‘What is it to understand a language?’We’ve been seeing, however, that this
untendentious methodological demand often comports with a substantive
metaphysical agenda: viz. the reduction of concepts and meanings to
epistemic capacities.
Thus Michael Dummett (1993a: 4), for one illustrious example, says
that “any theory of meaning which was not, or did not immediately yield,
a theory of understanding, would not satisfy the purpose for which,
philosophically, we require a theory of meaning”. There is, as previously
remarked, a reading on which this is true but harmless since whatever
ontological construal of the meaning of an expression we settle on will
automatically provide a corresponding construal of understanding the
expression as grasping its meaning. It is not, however, this truism that
Dummett is commending. Rather, he has it in mind that an acceptable
semantics must explicate linguistic content just by reference to the
“practical” capacities that users of a language have qua users of that
language. (Correspondingly, a theory that explicates the notion of
conceptual content would do so just by reference to the practical capacities
that having the concept bestows.) Moreover, if I read him right, Dummett
intends to impose this condition in a very strong form: the capacities upon
which linguistic meaning supervenes must be such as can be severally and
determinately manifested in behaviour. “An axiom earns its place in the

The Background Theory 5

4 Philosophical Introduction
theory [of meaning] . . . only to the extent that it is required for the
derivation of theorems the ascription of an implicit knowledge of which
to a speaker is explained in terms of specific abilities which manifest that
knowledge” (1993b: 38; my emphasis).
I don’t know for sure why Dummett believes that, but I darkly suspect
that he’s the victim of atavistic sceptical anxieties about communication.
Passages like the following recur in his writings:
What . . . constitutes a subject’s understanding the sentences of a language . . .?
[I]s it his having internalized a certain theory of meaning for that language? . . .
then indeed his behaviour when he takes part in linguistic interchange can at best
be strong but fallible evidence for the internalized theory. In that case, however, the
hearer’s presumption that he has understood the speaker can never be definitively
refuted or confirmed. (1993c: 180; notice how much work the word ‘definitively’
is doing here.)
So, apparently, the idea is that theories about linguistic content should
reduce to theories about language use; and theories about language use
should reduce to theories about the speaker’s linguistic capacities; and
theories about the speaker’s linguistic capacities are constrained by the
requirement that any capacity that is constitutive of the knowledge of a
language is one that the speaker’s use of the language can overtly and
specifically manifest. All this must be in aid of devising a bullet-proof antiscepticism
about communication, since it would seem that for purposes
other than refuting sceptics, all the theory of communication requires is
that a speaker’s utterances reliably cause certain ‘inner processes’ in the
hearer; specifically, mental processes which eventuate in the hearer having
the thought that the speaker intended him to have.
If, however, scepticism really is the skeleton in Dummett’s closet, the
worry seems to me to be doubly misplaced: first because the questions
with which theories of meaning are primarily concerned are metaphysical
rather than epistemic. This is as it should be; understanding what a thing
is, is invariably prior to understanding how we know what it is. And,
secondly, because there is no obvious reason why behaviourally grounded
inferences to attributions of concepts, meanings, mental processes,
communicative intentions, and the like should be freer from normal
inductive risk than, as it might be, perceptually grounded attributions of
tails to cats. The best we get in either case is “strong but fallible evidence”.
Contingent truths are like that as, indeed, Hume taught us some while
back. This is, no doubt, the very attitude that Dummett means to reject as
inadequate to the purposes for which we “philosophically” require a
theory of meaning. So much the worse, perhaps, for the likelihood that
philosophers will get from a theory of meaning what Dummett says that
The Background Theory 5
they require. I, for one, would not expect a good account of what concepts
are to refute scepticism about other minds any more than I’d expect a good
account of what cats are to refute scepticism about other bodies. In both
cases, I am quite prepared to settle for theories that are merely true.
Methodological inhibitions flung to the wind, then, here is how I
propose to organize our trip. Very roughly, concepts are constituents of
mental states. Thus, for example, believing that cats are animals is a
paradigmatic mental state, and the concept ANIMAL is a constituent of
the belief that cats are animals (and of the belief that animals sometimes
bite; etc. I’m leaving it open whether the concept ANIMAL is likewise a
constituent of the belief that some cats bite; we’ll raise that question
presently). So the natural home of a theory of concepts is as part of a
theory of mental states. I shall suppose throughout this book that RTM
is the right theory of (cognitive) mental states. So, I’m going to start with
an exposition of RTM: which is to say, with an exposition of a theory
about what mental states and processes are. It will turn out that mental
states and processes are typically species of relations to mental
representations, of which latter concepts are typically the parts.
To follow this course is, in effect, to assume that it’s OK for theorizing
about the nature of concepts to precede theorizing about concept
possession. As we’ve been seeing, barring a metaphysical subtext, that
assumption should be harmless; individuation theories and possession
theories are trivially intertranslatable. Once we’ve got RTM in place,
however, I’m going to argue for a very strong version of psychological
atomism; one according to which what concepts you have is conceptually
and metaphysically independent of what epistemic capacities you have. If
this is so, then patently concepts couldn’t be epistemic capacities.
I hope not to beg any questions by proceeding in this way; or at least not
to get caught begging any. But I do agree that if there is a knock-down, a
priori argument that concepts are logical constructs out of capacities, then
my view about their ontology can’t be right and I shall have to give up my
kind of cognitive science. Oh, well. If there’s a knock-down, a priori
argument that cats are logical constructs out of sensations, then my views
about their ontology can’t be right either, and I shall have to give up my
kind of biology. Neither possibility actually worries me a lot.
So, then, to begin at last:
RTM
RTM is really a loose confederation of theses; it lacks, to put it mildly, a
canonical formulation. For present purposes, let it be the conjunction of
the following:
6 Philosophical Introduction
First Thesis: Psychological explanation is typically nomic and is
intentional through and through. The laws that psychological explanations
invoke typically express causal relations among mental states
that are specified under intentional description; viz. among mental
states that are picked out by reference to their contents. Laws about
causal relations among beliefs, desires, and actions are the paradigms.
I’m aware there are those (mostly in Southern California, of course) who
think that intentional explanation is all at best pro tem, and that theories
of mind will (or anyhow should) eventually be couched in the putatively
purely extensional idiom of neuroscience. But there isn’t any reason in the
world to take that idea seriously and, in what follows, I don’t.
There are also those who, though they are enthusiasts for intentional
explanation, deny the metaphysical possibility of laws about intentional
states. I don’t propose to take that seriously in what follows either. For
one thing, I find the arguments that are said to show that there can’t be
intentional laws very hard to follow. For another thing, if there are no
intentional laws, then you can’t make science out of intentional explanations;
in which case, I don’t understand how intentional explanation could
be better than merely pro tem. Over the years, a number of philosophers
have kindly undertaken to explain to me what non-nomic intentional
explanations would be good for. Apparently it has to do with the
intentional realm (or perhaps it’s the rational realm) being autonomous.
But I’m afraid I find all that realm talk very hard to follow too.What is the
matter with me, I wonder?3
Second Thesis: ‘Mental representations’ are the primitive bearers of
intentional content.
Both ontologically and in order of explanation, the intentionality of the
propositional attitudes is prior to the intentionality of natural languages;
and, both ontologically and in order of explanation, the intentionality of
mental representations is prior to the intentionality of propositional
attitudes.
Just for purposes of building intuitions, think of mental representations
on the model of what Empiricist philosophers sometimes called ‘Ideas’.
That is, think of them as mental particulars endowed with causal powers
and susceptible of semantic evaluation. So, there’s the Idea DOG. It’s
satisfied by all and only dogs, and it has associative-cum-causal relations
to, for example, the Idea CAT. So DOG has conditions of semantic
evaluation and it has causal powers, as Ideas are required to do.
The Background Theory 7
3 The trouble may well have to do with my being a Hairy Realist. See Fodor 1995b.

8 Philosophical Introduction

Since a lot of what I want to say about mental representations includes
what Empiricists did say about Ideas, it might be practical and pious to
speak of Ideas rather than mental representations throughout. But I don’t
propose to do so. The Idea idea is historically intertwined with the idea
that Ideas are images, and I don’t want to take on that commitment. To a
first approximation, then, the idea that there are mental representations is
the idea that there are Ideas minus the idea that Ideas are images.
RTM claims that mental representations are related to propositional
attitudes as follows: for each event that consists of a creature’s having a
propositional attitude with the content P (each such event as Jones’s
believing at time t that P) there is a corresponding event that consists of
the creature’s being related, in a characteristic way, to a token mental
representation that has the content P. Please note the meretricious
scrupulousness with which metaphysical neutrality is maintained. I did
not say (albeit I’m much inclined to believe) that having a propositional
attitude consists in being related (in one or other of the aforementioned
‘characteristic ways’) to a mental representation.
I’m also neutral on what the ‘characteristic ways’ of being related to
mental representations are. I’ll adopt a useful dodge that Stephen Schiffer
invented: I assume that everyone who has beliefs has a belief box in his
head. Then:
For each episode of believing that P, there is a corresponding episode
of having, ‘in one’s belief box’, a mental representation which means
that P.
Likewise, mutatis mutandis, for the other attitudes. Like Schiffer, I don’t
really suppose that belief boxes are literally boxes, or even that they
literally have insides. I assume that the essential conditions for beliefboxhood
are functional. Notice, in passing, that this is not tantamount to
assuming that “believe” has a ‘functional definition’. I doubt that “believe”
has any definition. That most—indeed, overwhelmingly most—words
don’t have will be a main theme in the third chapter. But denying, as a
point of semantics, that “believe” has a functional definition is compatible
with asserting, as a point of metaphysics, that belief has a functional
essence. Which I think that it probably does. Ditto, mutatis mutandis,
“capitalism”, “carburettor”, and the like. (Compare Devitt 1996;
Carruthers 1996, both of whom run arguments that depend on not
observing this distinction.)
RTM says that there is no believing-that-P episode without a
corresponding tokening-of-a-mental-representation episode, and it
contemplates no locus of original intentionality except the contents of
mental representations. In consequence, so far as RTMs are concerned, to
8 Philosophical Introduction
explain what it is for a mental representation to mean what it does is to
explain what it is for a propositional attitude to have the content that it
does. I suppose that RTM leaves open the metaphysical possibility that
there could be mental states whose content does not, in this sense, derive
from the meaning of corresponding mental representations. But it takes
such cases not to be nomologically possible, and it provides no hint of an
alternative source of propositional objects for the attitudes.
Finally, English inherits its semantics from the contents of the beliefs,
desires, intentions, and so forth that it’s used to express, as per Grice and
his followers. Or, if you prefer (as I think, on balance, I do), English has
no semantics. Learning English isn’t learning a theory about what its
sentences mean, it’s learning how to associate its sentences with the
corresponding thoughts. To know English is to know, for example, that the
form of words ‘there are cats’ is standardly used to express the thought
that there are cats; and that the form of words ‘it’s raining’ is standardly
used to express the thought that it’s raining; and that the form of words
‘it’s not raining’ is standardly used to express the thought that it’s not
raining; and so on for in(de)finitely many other such cases.
Since, according to RTM, the content of linguistic expressions depends
on the content of propositional attitudes, and the content of propositional
attitudes depends on the content of mental representations, and since the
intended sense of ‘depends on’ is asymmetric, RTM tolerates the
metaphysical possibility of thought without language; for that matter, it
tolerates the metaphysical possibility of mental representation without
thought. I expect that many of you won’t like that. I’m aware that there is
rumoured to be an argument, vaguely Viennese in provenance, that proves
that ‘original’, underived intentionality must inhere, not in mental
representations nor in thoughts, but precisely in the formulas of public
languages. I would be very pleased if such an argument actually turned up,
since then pretty nearly everything I believe about language and mind
would have been refuted, and I could stop worrying about RTM, and
about what concepts are, and take off and go sailing, a pastime that I
vastly prefer. Unfortunately, however, either nobody can remember how
the argument goes, or it’s a secret that they’re unprepared to share with me.
So I’ll forge on.
Third Thesis: Thinking is computation.
A theory of mind needs a story about mental processes, not just a story
about mental states. Here, as elsewhere, RTM is closer in spirit to Hume
than it is to Wittgenstein or Ryle. Hume taught that mental states are
relations to mental representations, and so too does RTM (the main
difference being, as we’ve seen, that RTM admits, indeed demands, mental
The Background Theory 9
representations that aren’t images). Hume also taught that mental
processes (including, paradigmatically, thinking) are causal relations among
mental representations.4 So too does RTM. In contrast to Hume, and to
RTM, the logical behaviourism of Wittgenstein and Ryle had, as far as I
can tell, no theory of thinking at all (except, maybe, the silly theory that
thinking is talking to oneself). I do find that shocking. How could they
have expected to get it right about belief and the like without getting it
right about belief fixation and the like?
Alan Turing’s idea that thinking is a kind of computation is now, I
suppose, part of everybody’s intellectual equipment; not that everybody
likes it, of course, but at least everybody’s heard of it. That being so, I
shall pretty much take it as read for the purposes at hand. In a nutshell:
token mental representations are symbols. Tokens of symbols are physical
objects with semantic properties. To a first approximation, computations
are those causal relations among symbols which reliably respect semantic
properties of the relata. Association, for example, is a bona fide
computational relation within the meaning of the act. Though whether
Ideas get associated is supposed to depend on their frequency, contiguity,
etc., and not on what they’re Ideas of, association is none the less supposed
reliably to preserve semantic domains: Jack-thoughts cause Jill-thoughts,
salt-thoughts cause pepper-thoughts, red-thoughts cause green-thoughts,
and so forth.5 So, Hume’s theory of mental processes is itself a species of
RTM, an upshot that pleases me.
Notoriously, however, it’s an inadequate species. The essential problem
in this area is to explain how thinking manages reliably to preserve truth;
and Associationism, as Kant rightly pointed out to Hume, hasn’t the
resources to do so. The problem isn’t that association is a causal relation,
or that it’s a causal relation among symbols, or even that it’s a causal
relation among mental symbols; it’s just that their satisfaction conditions
aren’t among the semantic properties that associates generally share. To
the contrary, being Jack precludes being Jill, being salt precludes being
pepper, being red precludes being green, and so forth. By contrast, Turing’s
account of thought-as-computation showed us how to specify causal
relations among mental symbols that are reliably truth-preserving. It
thereby saved RTM from drowning when the Associationists went under.
I propose to swallow the Turing story whole and proceed. First,
however, there’s an addendum I need and an aside I can’t resist.
10 Philosophical Introduction
4 And/or among states of entertaining them. I’ll worry about this sort of ontological
nicety only where it seems to matter.
5 Why relations that depend on merely mechanical properties like frequency and
contiguity should preserve intentional properties like semantic domain was what
Associationists never could explain. That was one of the rocks they foundered on.

The Background Theory 11

Addendum: if computation is just causation that preserves semantic
values, then the thesis that thought is computation requires of mental
representations only that they have semantic values and causal powers
that preserve them. I now add a further constraint: many mental
representations have constituent ( part/whole) structure, and many mental
processes are sensitive to the constituent structure of the mental
representations they apply to. So, for example, the mental representation
that typically gets tokened when you think . . . brown cow . . . has, among
its constituent parts, the mental representation that typically gets tokened
when you think . . . brown . . .; and the computations that RTM says get
performed in processes like inferring from . . . brown cow . . . to . . .
brown . . . exploit such part/whole relations. Notice that this is an
addendum (though it’s one that Turing’s account of computation was
designed to satisfy). It’s untendentious that RTM tolerates the possibility
of conceptual content without constituent structure since everybody who
thinks that there are mental representations at all thinks that at least some
of them are primitive.6
The aside I can’t resist is this: following Turing, I’ve introduced the
notion of computation by reference to such semantic notions as content
and representation; a computation is some kind of content-respecting
causal relation among symbols. However, this order of explication is OK
only if the notion of a symbol doesn’t itself presuppose the notion of a
computation. In particular, it’s OK only if you don’t need the notion of a
computation to explain what it is for something to have semantic
properties.We’ll see, almost immediately, that the account of the semantics
of mental representations that my version of RTM endorses, unlike the
account of thinking that it endorses, is indeed non-computational.
Suppose, however, it’s your metaphysical view that the semantic
properties of a mental representation depend, wholly or in part, upon the
computational relations that it enters into; hence that the notion of a
computation is prior to the notion of a symbol. You will then need some
other way of saying what it is for a causal relation among mental
representations to be a computation; some way that does not presuppose
such notions as symbol and content.7 It may be possible to find such a
notion of computation, but I don’t know where. (Certainly not in Turing,
The Background Theory 11
6 Connectionists are committed, willy-nilly, to all mental representations being
primitive; hence their well-known problems with systematicity, productivity, and the like.
More on this in Chapter 5.
7 Not, of course, that there is anything wrong with just allowing ‘symbol’ and
‘computation’ to be interdefined. But that option is not available to anyone who takes the
theory that thought is computation to be part of a naturalistic psychology; viz. part of a
programme of metaphysical reduction. As Turing certainly did; and as do I.
who simply takes it for granted that the expressions that computing
machines crunch are symbols; e.g. that they denote numbers, functions,
and the like.) The attempts I’ve seen invariably end up suggesting (or
proclaiming) that every causal process is a kind of computation, thereby
trivializing Turing’s nice idea that thought is.
So much for mental processes.
Fourth Thesis: Meaning is information (more or less).
There actually are, in the land I come from, philosophers who would agree
with the gist of RTM as I’ve set it forth so far. Thesis Four, however, is
viewed as divisive even in that company. I’m going to assume that what
bestows content on mental representations is something about their
causal-cum-nomological relations to the things that fall under them: for
example, what bestows upon a mental representation the content dog is
something about its tokenings being caused by dogs.
I don’t want to pursue, beyond this zero-order approximation, the
question just which causal-cum-nomological relations are content-making.
Those of you who have followed the literature on the metaphysics of
meaning that Fred Dretske’s book Knowledge and the Flow of Information
(1981) inspired will be aware that that question is (ahem!) mootish. But I
do want to emphasize one aspect of the identification of meaning with
information that is pretty widely agreed on and that impacts directly on
any proposal to amalgamate an informational semantics with RTM: if
meaning is information, then coreferential representations must be
synonyms.
Just how this works depends, of course, on what sort of causal-cumnomological
covariation content is and what sort of things you think
concepts represent (properties, actual objects, possible objects, or
whatever). Suppose, for example, that you run the kind of informational
semantics that says:
A representationR expresses the property P in virtue of its being a law
that things that are P cause tokenings of R (in, say, some still-to-bespecified
circumstances C).
And suppose, for the sake of the argument, that being water and being
H2O are (not merely coextensive but) the same property. It then follows
that if it’s a law that WATER tokens covary with water (in C) it’s also a law
that WATER tokens covary with H2O (in C). So a theory that says that
WATER means water in virtue of there being the first law is also required
to say that WATER means H2O in virtue of there being the second.
Parallel reasoning shows that H2O means water, hence that WATER and
H2O mean the same.
12 Philosophical Introduction
You may wonder why I want to burden my up to now relatively
uncontroversial version of RTM by adding a theory of meaning that has
this uninviting consequence; and how I could reasonably suppose that
you’ll be prepared to share the burden by granting me the addition. Both
questions are fair.
As to the first, suppose that coextension is not sufficient for synonymy
after all. Then there must be something else to having a concept with a
certain content than having a mental representation with the kind of
world-to-symbol causal connections that informational semantics talks
about. The question arises: what is this extra ingredient? There is, as
everybody knows, a standard answer; viz. that what concepts one has is
determined, at least in part, by what inferences one is prepared to draw or to
accept. If it is possible to have the concept WATER and not have the
concept H2O, that’s because it’s constitutive of having the latter, but not
constitutive of having the former, that you accept such inferences as
contains H2O ® contains H. It is, in short, received wisdom that content
may be constituted in part by informational relations, but that unless
coreference is sufficient for synonymy, it must also be constituted by
inferential relations. I’ll call any theory that says this sort of thing an
Inferential Role Semantics (IRS).
I don’t want content to be constituted, even in part, by inferential
relations. For one thing, as we just saw, I like Turing’s story that inference
(qua mental process) reduces to computation; i.e. to operations on symbols.
For fear of circularity, I can’t both tell a computational story about what
inference is and tell an inferential story about what content is. Prima facie,
at least, if I buy into Inferential Role Semantics, I undermine my theory
of thinking.
For a second thing, I am inclined to believe that an inferential role
semantics has holistic implications that are both unavoidable and
intolerable. A main reason I love RTM so much is that the computational
story about mental processes fits so nicely with the story that psychological
explanation is subsumption under intentional laws; viz. under laws that
apply to a mental state in virtue of its content. Since computation is
presumed to respect content, RTM can maybe provide the mechanism
whereby satisfying the antecedent of an intentional law necessitates the
satisfaction of its consequent (see Fodor 1994: ch. 1). But I think it’s pretty
clear that psychological explanation can’t be subsumption under
intentional laws if the metaphysics of intentionality is holistic. (See Fodor
and Lepore 1992.)
For a third thing, as previously noted, the main point of this book will
be to argue for an atomistic theory of concepts. I’m going to claim, to put
it very roughly, that satisfying the metaphysically necessary conditions for

14 Philosophical Introduction

The Background Theory 13
having one concept never requires satisfying the metaphysically necessary
conditions for having any other concept. (Well, hardly ever. See below.)
Now, the status of conceptual atomism depends, rather directly, on
whether coreference implies synonymy. For, if it doesn’t, and if it is
inferential role that makes the difference between content and reference,
then every concept must have an inferential role. But it’s also common
ground that you need more than one concept to draw an inference, so if
IRS is true, conceptual atomism isn’t. No doubt this line of thought could
use a little polishing, but it’s surely basically sound.
So, then, if I’m going to push for an atomistic theory of concepts, I
must not hold that one’s inferential dispositions determine, wholly or in
part, the content of one’s concepts. Pure informational semantics allows
me not to hold that one’s inferential dispositions determine the content of
one’s concepts because it says that content is constituted, exhaustively, by
symbol–world relations.
It’s worth keeping clear on how the relation between concept possession
and concept individuation plays out on an informational view: the content
of, for example, BACHELOR is constituted by certain (actual and/or
counterfactual) causal-cum-nomic relations between BACHELORtokenings
and tokenings of instantiated bachelorhood. Presumably
bachelorhood is itself individuated, inter alia, by the necessity of its relation
to being unmarried. So, ‘bachelors are unmarried’ is conceptually necessary
in the sense that it’s guaranteed by the content of BACHELOR together
with the metaphysics of the relevant property relations. It follows, trivially,
that having BACHELOR is having a concept which can apply only to
unmarried things; this is the truism that the interdefinability of concept
individuation and concept possession guarantees. But nothing at all about
the epistemic condition of BACHELOR owners (e.g. about their
inferential or perceptual dispositions or capacities) follows from the
necessity of ‘bachelors are unmarried’; it doesn’t even follow that you can’t
own BACHELOR unless you own UNMARRIED. Informational semantics
permits atomism about concept possession even if (even though) there
are conceptually necessary truths.8 This is a sort of point that will recur
repeatedly as we go along.
So much for why I want an informational semantics as part of my
RTM. Since it is, of course, moot whether I can have one, the best I can
hope for is that this book will convince you that conceptual atomism is OK
unless there is a decisive, independent argument against the reduction of
meaning to information. I’m quite prepared to settle for this since I’m
14 Philosophical Introduction
8 What it doesn’t do is guarantee the connection between what’s conceptually necessary
and what’s a priori. But perhaps that’s a virtue.
pretty sure that there’s no such argument. In fact, I think the dialectic is
going to have to go the other way around: what settles the metaphysical
issue between informational theories of meaning and inferential role
theories of meaning is that the former, but not the latter, are compatible
with an atomistic account of concepts. And, as I’ll argue at length, there
are persuasive independent grounds for thinking that atomism about
concepts must be true.
In fact, I’m going to be more concessive still. Given my view that
content is information, I can’t, as we’ve just seen, afford to agree that the
content of the concept H2O is different from the content of the concept
WATER. But I am entirely prepared to agree that they are different
concepts. In effect, I’m assuming that coreferential representations are ipso
facto synonyms and conceding that, since they are, content individuation
can’t be all that there is to concept individuation.
It may help make clear how I’m proposing to draw the boundaries to
contrast the present view with what I take to be a typical Fregean position;
one according to which concepts are distinguished along two (possibly
orthogonal) parameters; viz. reference and Mode of Presentation. (So, for
example, the concept WATER is distinct from the concept DOG along
both parameters, but it’s distinct from the concept H2O only in respect of
the second.) I’ve diverged from this sort of scheme only in that some
Fregeans (e.g. Frege) identify modes of presentation with senses. By
contrast, I’ve left it open what modes of presentation are, so long as they
are what distinguish distinct but coreferential concepts. So far, then, I’m
less extensively committed than a Fregean, but I don’t think that I’m
committed to anything that a Fregean is required to deny.
Alas, ecumenicism has to stop somewhere. The fifth (and final thesis) of
my version of RTM does depart from the standard Frege architecture.
Fifth Thesis: Whatever distinguishes coextensive concepts is ipso facto
‘in the head’. This means, something like that it’s available to be a
proximal cause (/effect) of mental processes.9
As I understand it, the Fregean story makes the following three claims
about modes of presentation:
5.1 MOPs are senses; for an expression to mean what it does is for the
expression to have the MOP that it does.
The Background Theory 15
9 I take it that one of the things that distinguishes Fregeans sans phrase from neo-
Fregeans (like e.g. Peacocke 1992) is that the latter are not committed to Fege’s antimentalism
and are therefore free to agree with Thesis Five if they’re so inclined. Accordingly,
for the neo- sort of Fregean, the sermon that follows will seem to be preached to the
converted.
5.2 Since MOPs can distinguish concepts, they explain how it is
possible to entertain one, but not the other, of two coreferential
concepts; e.g. how it is possible have the concept WATER but not
the concept H2O, hence how it is possible to have (de dicto) beliefs
about water but no (de dicto) beliefs about H2O.
5.3 MOPs are abstract objects; hence they are non-mental.
In effect, I’ve signed on for 5.2; it’s the claim about MOPs that everybody
must accept who has any sympathy at all for the Frege programme. But I
think there are good reasons to believe that 5.2 excludes both 5.1 and 5.3.
In which case, I take it that 5.1 and 5.3 will have to go.
—What’s wrong with 5.1: 5.1 makes trouble for 5.2: it’s unclear that you
can hold onto 5.2 if you insist, as Frege does, that MOPs be identified
with senses. One thing (maybe the only one) that we know for sure about
senses is that synonyms share them. So if MOPs are senses and distinct but
coextensive concepts are distinguished (solely) by their MOPs, then
synonymous concepts must be identical, and it must not be possible to
think either without thinking the other. (This is the so-called ‘substitution
test’ for distinguishing modes of presentation.) But (here I follow Mates
1962), it is possible for Fred to wonder whether John understands that
bachelors are unmarried men even though Fred does not wonder whether
John understands that unmarried men are unmarried men. The moral seems
to be that if 5.2 is right, so that MOPs just are whatever it is that the
substitution test tests for, then it’s unlikely that MOPs are senses.
Here’s a similar argument to much the same conclusion. Suppose I tell
you that Jackson was a painter and that Pollock was a painter, and I tell
you nothing else about Jackson or Pollock. Suppose, also, that you believe
what I tell you. It looks like that fixes the senses of the names ‘Jackson’ and
‘Pollock’ if anything could; and it looks like it fixes them as both having
the same sense: viz. a painter. (Mutatis mutandis, it looks as though I have
fixed the same inferential role for both.) Yet, in the circumstances
imagined, it’s perfectly OK—perfectly conceptually coherent—for you to
wonder whether Jackson and Pollock were the same painter. (Contrast the
peculiarity of your wondering, in such a case, whether Jackson was
Jackson or whether Pollock was Pollock.) So, then, by Frege’s own test,
JACKSON and POLLOCK count as different MOPs. But if concepts with
the same sense can be different MOPs then, patently, MOPs can’t be
senses. This isn’t particularly about names, by the way. If I tell you that a
flang is a sort of machine part and a glanf is a sort of machine part, it’s
perfectly OK for you to wonder whether a glanf is a flang.10
16 Philosophical Introduction
10 You can’t, of course, do this trick with definite descriptions since they presuppose

The Background Theory 17

Oh well, maybe my telling you that Jackson was a painter and Pollock
was a painter didn’t fix the same senses for both names after all. I won’t
pursue that because, when it comes to senses, who can prove what fixes
what? But it hardly matters since, on reflection, what’s going on doesn’t
seem to have to do with meaning. Rather, the governing principle is a piece
of logical syntax: If ‘a’ and ‘b’ are different names, then the inference from
‘Fa’ to ‘Fb’ is never conceptually necessary.11 (It’s even OK to wonder
whether Jackson is Jackson, if the two ‘Jacksons’ are supposed to be
tokens of different but homonymous name types.) It looks like the moral
of this story about Jackson and Pollock is the same as the moral of
Mates’s story about bachelors and unmarried men. Frege’s substitution
test doesn’t identify senses. Correspondingly, if it is stipulated that MOPs
are whatever substitution salve veritate turns on, then MOPs have to be
sliced a good bit thinner than senses. Individuating MOPs is more like
individuating forms of words than it is like individuating meanings.
I take these sorts of considerations very seriously. They will return full
strength at the end of Chapter 2.
—What’s wrong with 5.3: This takes a little longer to say, but here is the
short form. Your having n MOPs for water explains why you have n ways
of thinking about water only on the assumption that there is exactly one way
to grasp each MOP.12 The question thus arises what, if anything, is
supposed to legitimize this assumption. As far as I can tell, unless you’re
prepared to give up 5.3, the only answer a Fregean theory allows you is:
sheer stipulation.
Terminological digression (I’m sorry to have to ask you to split these
hairs, but this is a part of the wood where it is very easy to get lost): I use
‘entertaining’ and ‘grasping’ a MOP (/concept) interchangeably. Entertaining/
grasping a MOP doesn’t, of course, mean thinking about the MOP;
The Background Theory 17
uniqueness of reference. If you mean by “Jackson” the horse that bit John, and you mean
by “Pollock” the horse that bit John, you can’t coherently wonder whether Jackson is the
same horse as Pollock.
By the way, I have the damnedest sense of déjà vu about the argument in the text; I
simply can’t remember whether I read it somewhere or made it up. If it was you I snitched
it from, Dear Reader, please do let me know.
11 More precisely: it’s never conceptually necessary unless either the inference from Fa
to a = b or the inference from Fb to a = b is itself conceptually necessary. (For example, let
Fa be: ‘a has the property of being identical to b’.)
12 Or, if there is more than one way to grasp a MOP, then all of the different ways of
doing so must correspond to the same way of thinking its referent. I won’t pursue this
option in the text; suffice it that doing so wouldn’t help with the problem that I’m raising.
Suppose that there is more than one way to grasp a MOP; and suppose that a certain MOP
is a mode of presentation of Moe. Then if, as Frege requires, there is a MOP corresponding
to each way of thinking a referent, all the ways of grasping the Moe-MOP must be the
same way of thinking of Moe. I claim that, precisely because 5.3 is in force, Frege’s theory
has no way to ensure that this is so.
there are as many ways of thinking about a MOP as there are of thinking
about a rock or a number. That is, innumerably many; one for each mode
of presentation of the MOP. Rather, MOPs are supposed to be the vehicles
of thought, and entertaining a MOP means using it to present to thought
whatever the MOP is a mode of presentation of; it’s thinking with the
MOP, not thinking about it. End digression. My point is that if there is
more than one way to grasp a MOP, then ‘grasping a water-MOP is a way
of thinking about water’ and ‘Smith has only one water-MOP’ does not
entail that Smith has only one way of thinking about water.
So, then, what ensures that there is only one way to grasp a MOP? Since
Frege thinks that MOPs are senses and that sense determines reference
(concepts with the same sense must be coextensive) he holds, in effect, that
MOP identity and concept identity come to the same thing. So my
question can be put just in terms of the latter: that one has as many ways
of thinking of a referent as one has concepts of the referent depends on
there being just one way to entertain each concept. What, beside
stipulation, guarantees this?
Perhaps the following analogy (actually quite close, I think) will help to
make the situation clear. There are lots of cases where things other, and
less problematic, than Fregean senses might reasonably be described as
‘modes of presentation’; viz. as being used to present the object of a
thought to the thought that it’s the object of. Consider, for example, using
a diagram of a triangle in geometrical reasoning about triangles. It seems
natural, harmless, maybe even illuminating, to say that one sometimes
reasons about triangles via such a diagram; and that the course of the
reasoning may well be affected (e.g. facilitated) by choosing to do so. In a
pretty untendentious sense, the diagram functions to present triangles (or
triangularity) to thought; OK so far.
But notice a crucial difference between a diagram that functions as a
mode of presentation and a Fregean sense that does: in the former case,
there’s more—lots more—than one kind of object that the diagram can be
used to present. The very same diagram can represent now triangles, now
equilateral triangles, now closed figures at large, now three-sided figures at
large . . . etc. depending on what intentional relation the reasoner bears to
it; depending, if you like, on how the reasoner entertains it. In this sort of
case, then, lots of concepts correspond to the same mode of presentation.
Or, putting it the other way round, what corresponds to the reasoner’s
concept is not the mode of presentation per se, but the mode of presentation
together with how it is entertained.
A diagram can be used in all sorts of ways to present things to thought,
but a Fregean sense can’t be on pain of senses failing to individuate concepts;
which is, after all, what they were invoked for in the first place. So,
18 Philosophical Introduction
question: what stops senses from behaving like diagrams? What guarantees
that each sense can serve in only one way to present an object to a thought?
I think that, on the Frege architecture with 5.3 in force, nothing prevents
this except brute stipulation.
As far as I know, the standard discussions have pretty generally failed
to recognize that Frege’s architecture has this problem, so let me try once
more to make clear just what the problem is. It’s because there is more
than one way to think about a referent that Frege needs to invoke MOPs
to individuate concepts; referents can’t individuate concepts because lots
of different concepts can have the same referent. Fine. But Frege holds
that MOPs can individuate concepts; that’s what MOPs are for. So he
mustn’t allow that different MOPs can correspond to the same concept,
nor may he allow that a MOP can correspond to a concept in more than one
way. If he did, then each way of entertaining the MOP would
(presumably) correspond to a different way of thinking the referent, and
hence (presumably) to a different concept of the referent.Whereas MOPs
are supposed to correspond to concepts one-to-one.
So, the question that I’m wanting to commend to you is: what, if
anything, supports the prohibition against proliferating ways of grasping
MOPs? Frege’s story can’t be: ‘There is only one way of thinking a referent
corresponding to each mode of presentation of the referent because there
is only one way of entertaining each mode of presentation of a referent;
and there is only one way of entertaining each mode of presentation of a
referent because I say that’s all there is.’ Frege needs something that can
both present referents to thought and individuate thoughts; in effect, he
needs a kind of MOP that is guaranteed to have only one handle. He can’t,
however, get one just by wanting it; he has to explain how there could be
such things. And 5.3 is in his way.
I think that if MOPs can individuate concepts and referents can’t, that
must be because MOPs are mental objects and referents aren’t. Mental
objects are ipso facto available to be proximal causes of mental processes;
and it’s plausible that at least some mental objects are distinguished by
the kinds of mental processes that they cause; i.e. they are functionally
distinguished.13 Suppose that MOPs are in fact so distinguished. Then it’s
hardly surprising that there is only one way a mind can entertain each
MOP: since, on this ontological assumption, functionally equivalent
MOPs are ipso facto identical, the question ‘Which MOP are you
The Background Theory 19
13 This doesn’t, please notice, commit me to holding that the individuation of thought
content is functional. Roughly, that depends on whether Frege is right that whatever can
distinguish coextensive concepts is ipso facto the sense of the concepts; i.e. it depends on
assuming 5.1. Which, however, I don’t; see above.

20 Philosophical Introduction

entertaining?’ and the question ‘Which functional state is your mind in
when you entertain it?’ are required to get the same answer.
Frege’s structural problem is that, though he wants to be an externalist
about MOPs, the architecture of his theory won’t let him.14 Frege’s reason
for wanting to be an externalist about MOPs is that he thinks, quite
wrongly, that if MOPs are mental then concepts won’t turn out to be
public. But if MOPs aren’t mental, what kind of thing could they be such
that necessarily for each MOP there is only one way in which a mind can
entertain it? (And/or: what kind of mental state could entertaining a MOP
be such that necessarily there is only one way to entertain each MOP?) As
far as I can tell, Frege’s story offers nothing at all to scratch this itch with.
If, however, MOPS are in the head,15 then they can be proximal mental
causes and are, to that extent, apt for functional individuation. If MOPs
are both in the head and functionally individuated, then a MOP’s identity
can be constituted by what happens when you entertain it.16 And if the
identity of a MOP is constituted by what happens when you entertain it,
then of course there is only one way to entertain each MOP. In point of
metaphysical necessity, the alleged ‘different ways of entertaining a MOP’
would really be ways of entertaining different MOPs.
The moral, to repeat, is that even Frege can’t have 5.3 if he holds onto
5.1. Even Frege should have been a mentalist about MOPs if he wished to
remain in other respects a Fregean. On the other hand (perhaps this goes
without saying), to claim that MOPs must be mental objects is quite
compatible with also claiming that they are abstract objects, and that
abstract objects are not mental. The apparent tension is reconciled by
taking MOPS-qua-things-in-the-head to be the tokens of which MOPSqua-
abstract-objects are the types. It seems that Frege thought that if
meanings can be shared it somehow follows that they can’t also be
20 Philosophical Introduction
14 In this usage, an ‘externalist’ is somebody who says that ‘entertaining’ relates a
creature to something mind-independent, so Frege’s externalism is entailed by his Platonism.
Contrast the prima facie quite different Putnam/Kripke notion, in which an externalist is
somebody who says that what you are thinking depends on what world you’re in. (Cf. Preti
1992, where the distinction between these notions of externalism is sorted out, and some of
the relations between them are explored.)
15 This way of talking is, of course, entirely compatible with the current fashions in
Individualism, Twins, and the like. Twins are supposed to show that referents can distinguish
concepts whose causal roles are the same. For the demonstration to work, however, you’ve
got to assume that Twins ipso facto have the causal roles of their concepts in common; viz.
that whatever contents may supervene on, what causal roles supervene on is inside the head.
That’s precisely what I’m supposing in the text.
16 Notice that this is not to say that concepts are individuated by the mental processes
they cause, since a concept is a MOP together with a content; and I’ve taken an
informational view of the individuation of contents. It’s thus open to my version of RTM
that ‘Twin-Earth’ cases involve concepts with different contents but the same MOPs.
The Background Theory 21
particulars. But it beats me why he thought so. You might as well argue
from ‘being a vertebrate is a universal’ to ‘spines aren’t things’.
We’re almost through with this, but I do want to tell you about an
illuminating remark that Ernie Sosa once made to me. I had mentioned to
Ernie that I was worried about why, though there are lots of ways to grasp
a referent, there’s only one way to grasp a MOP. He proceeded to poohpooh
my worry along the following lines. “Look,” he said, “it’s pretty clear
that there is only one way to instantiate a property, viz. by having it. It
couldn’t be, for example, that the property red is instantiated sometimes by
a thing’s being red and sometimes by a thing’s being green. I don’t suppose
that worries you much?” (I agreed that it hadn’t been losing me sleep.)
“Well,” he continued, with a subtle smile, “if you aren’t worried about there
being only one way to instantiate a property, why are you worried about there
being only one way to grasp a mode of presentation?”
I think that’s very clever, but I don’t think it will do. The difference is
this: It is surely plausible on the face of it that ‘instantiating property P’
is just being P; being red is all that there is to instantiating redness. But
MOP is a technical notion in want of a metaphysics. If, as seems likely, the
identity of a mental state turns on its causal role, then if MOPs are to
individuate mental states they will have to be the sorts of things that the
causal role of a mental state can turn on. But it’s a mystery how a MOP
could be that sort of thing if MOPs aren’t in the head. If (to put the point
a little differently) their non-mental objects can’t distinguish thoughts, how
can MOPS distinguish thoughts if they are non-mental too? It’s as though
the arithmetic difference between 3 and 4 could somehow explain the
psychological difference between thinking about 3 and thinking about 4.
That red things are what instantiate redness is a truism, so you can have
it for free. But Frege can’t have it for free that, although same denotation
doesn’t mean same mental state, same MOP does. That must depend on
some pretty deep difference between the object of thought and its vehicle.
Offhand, the only difference I can think of that would do the job is
ontological; it requires MOPs to be individuated by their roles as causes
and effects of mental states, and hence to themselves be mental. So I think
we should worry about why there’s only one way to grasp a MOP even
though I quite agree that we shouldn’t worry about why there’s only one
way to instantiate a property.
Well, then, that’s pretty much it for the background theory. All that
remains is to add that in for a penny, in for a pound; having gone as far as
we have, we might as well explicitly assume that MOPs are mental
representations. That, surely, is the natural thing to say if you’re supposing,
on the one hand, that MOPs are among the proximal determinants of
mental processes (as per Thesis Five) and that mental processes are
computations on structured mental representations (as per Thesis Two).
It’s really the basic idea of RTM that Turing’s story about the nature of
mental processes provides the very candidates for MOP-hood that Frege’s
story about the individuation of mental states independently requires. If
that’s true, it’s about the nicest thing that ever happened to cognitive
science.
So I shall assume that it is true. From here on, I’ll take for granted that
wherever mental states with the same satisfaction conditions have different
intentional objects (like, for example, wanting to swallow the Morning
Star and wanting to swallow the Evening Star) there must be
corresponding differences among the mental representations that get
tokened in the course of having them.
Now, finally, we’re ready to get down to work. I’m interested in such
questions as: ‘What is the structure of the concept DOG?’ Given RTM as
the background theory, this is equivalent to the question: ‘What is the
MOP in virtue of entertaining which thoughts have dogs as their
intentional objects?’ And this is in turn equivalent to the question: ‘What
is the structure of the mental representation DOG?’
And my answer will be that, on the evidence available, it’s reasonable to
suppose that such mental representations have no structure; it’s reasonable
to suppose that they are atoms.

Unphilosophical Introduction: What Concepts Have To Be

THIS is a book about concepts. Two of its main theses are:
—that if you are going to run a representational/computational theory
of mind (that is, any version of RTM; see Chapter 1) you will need
a theory of concepts.
And:
—that none of the theories of concepts that are currently taken at all
seriously either in cognitive science or in philosophy can conceivably
fill the bill.
To argue this, I shall first need to say what bill it is that needs to be filled.
That’s the burden of this chapter. I want to set out five conditions that an
acceptable theory of concepts would have to meet. Several chapters
following this one will be devoted to making clear by how much, and for
what reasons, current theories of concepts fail to meet them.
A word about the epistemic status of the conditions I’m about to
endorse: I regard them as fallible but not negotiable. Not negotiable, that
is, short of giving up on RTM itself; and RTM remains the only game in
town, even after all these years. In effect, I’m claiming that these
constraints on concepts follow just from the architecture of RTMs
together with some assumptions about cognitive processes and capacities
which, though certainly contingent, are none the less hardly possible to
doubt. (I mean, of course, hardly possible to doubt really, not hardly
possible to doubt philosophically.) If this is indeed the status of these
constraints, then I think we had better do what we can to construct a
theory of concepts that satisfies them.
So, then, here are my five not-negotiable conditions on a theory of
concepts.
1. Concepts are mental particulars; specifically, they satisfy whatever
ontological conditions have to be met by things that function as
mental causes and effects.
Since this is entailed by RTM (see Chapter 1), and hence is common to all
the theories of concepts I’ll consider, I won’t go on about it here. If,
however, you think that intentional causation explains behaviour only in
the way that the solubility of sugar explains its dissolving (see Ryle 1949),
or if you think that intentional explanations aren’t causal at all (see e.g.
Collins 1987 ), then nothing in the following discussion will be of much use
to you, and I fear we’ve reached a parting of the ways. At least one of us
is wasting his time; I do hope it’s you.
2. Concepts are categories and are routinely employed as such.
To say that concepts are categories is to say that they apply to things in the
world; things in the world ‘fall under them’. So, for example, Greycat the
cat, but not Dumbo the elephant, falls under the concept CAT. Which,
for present purposes, is equivalent to saying that Greycat is in the extension
of CAT, that ‘Greycat is a cat’ is true, and that ‘is a cat’ is true of Greycat.
I shall sometimes refer to this galaxy of considerations by saying that
applications of concepts are susceptible of ‘semantic evaluation’: claims, or
thoughts, that a certain concept applies to a certain thing are always
susceptible of evaluation in such semantical terms as satisfied/unsatisfied,
true/false, correct/incorrect, and the like. There are, to be sure, issues about
these various aspects of semantic evaluability, and about the relations
among them, that a scrupulous philosopher might well wish to attend to.
But in this chapter, I propose to keep the philosophy to a bare minimum.1
Much of the life of the mind consists in applying concepts to things. If
I think Greycat is a cat (de dicto, as it were), I thereby apply the concept
CAT to Greycat (correctly, as it happens). If, looking at Greycat, I take
him to be a cat, then too I apply the concept CAT to Greycat. (If looking
at Greycat I take him to be a meatloaf, I thereby apply the concept
MEATLOAF to Greycat; incorrectly, as it happens.) Or if, in reasoning
about Greycat, I infer that since he’s a cat he must be an animal, I thereby
proceed from applying one concept to Greycat to the licensed application
of another concept; the license consisting, I suppose, in things I know
about how the extensions of the concepts CAT and ANIMAL are related.
In fact, RTM being once assumed, most of cognitive psychology,
including the psychology of memory, perception, and reasoning, is about
how we apply concepts. And most of the rest is about how we acquire the
concepts that we thus apply. Correspondingly, the empirical data to which
cognitive psychologists are responsible consist largely of measures of
subject performance in concept application tasks. The long and short is:
whatever else a theory of concepts says about them, it had better exhibit
1 Or, at least, to confine it to footnotes.
concepts as the sorts of things that get applied in the course of mental
processes. I take it that consensus about this is pretty general in the
cognitive sciences, so I won’t labour it further here.
Caveat: it’s simply untendentious that concepts have their satisfaction
conditions essentially. Nothing in any mental life could be the concept
CAT unless it is satisfied by cats. It couldn’t be that there are some mental
lives in which the concept CAT applies to CATS and others in which it
doesn’t. If you haven’t got a concept that applies to cats, that entails that
you haven’t got the CAT concept. But though the satisfaction conditions
of a concept are patently among its essential properties, it does not follow
that the confirmation conditions of a concept are among its essential
properties. Confirmation is an epistemic relation, not a semantic relation,
and it is generally theory mediated, hence holistic. On the one hand, given
the right background theory, the merest ripple in cat infested waters might
serve to confirm an ascription of cathood; and, on the other hand, no catcontaining
layout is so well lit, or so utterly uncluttered, or so selfcertifying
that your failure to ascribe cathood therein would entail that
you lack the concept. In short, it is OK to be an atomist about the
metaphysical conditions for a concept’s having satisfaction conditions
(which I am and will try to convince you to be too), and yet be a holist
about the confirmation of claims that a certain concept is satisfied in a
certain situation. Shorter still: just as Quine and Duhem and those guys
taught us, there aren’t any criteria. So at least I shall assume throughout
what follows.
3. Compositionality: concepts are the constituents of thoughts and, in
indefinitely many cases, of one another. Mental representations
inherit their contents from the contents of their constituents.
Some terminology: I’ll use ‘thoughts’ as my cover term for the mental
representations which, according to RTMs, express the propositions that
are the objects of propositional attitudes. Thus, a belief that it will rain and
a hope that it will rain share a thought as well as a proposition which that
thought expresses. For present purposes, it will do to think of thoughts as
mental representations analogous to closed sentences, and concepts as
mental representations analogous to the corresponding open ones. It may
strike you that mental representation is a lot like language, according to my
version of RTM. Quite so; how could language express thought if that
were not the case?
Qua constituents of thoughts, and of each other, concepts play a certain
role in explaining why the propositional attitudes are productive and
systematic. The outlines of this story are well known, though by no means
untendentious:

26 Unphilosophical Introduction

26 Unphilosophical Introduction
Beliefs are productive in that there are infinitely many distinct ones that
a person can entertain (given, of course, the usual abstraction from
‘performance limitations’). Beliefs are systematic in that the ability to
entertain any one of them implies the ability to entertain many others that
are related to it in content. It appears, for example, to be conceptually
possible that there should be a mind that is able to grasp the proposition
that Mary loves John but not able to grasp the proposition that John loves
Mary. But, in point of empirical fact, it appears that there are no such
minds. This sort of symmetry of cognitive capacities is a ubiquitous
feature of mental life.2 It implies a corresponding symmetry of
representational capacities since RTM says, ‘no cognition without
representation’. That is, RTM says that you can’t grasp a proposition
without entertaining a thought.
So, the question presents itself: what must mental representation be like
if it is to explain the productivity and systematicity of beliefs? This
question is loaded, to be sure: that the systematicity of the attitudes
requires the systematicity of mental representation doesn’t itself require
that the systematicity of mental representation is what explains the
systematicity of the attitudes. Perhaps both are the effects of a common
cause. Maybe, for example, ‘the world’ somehow teaches the mind to be
systematic, and the systematicity of mental representation is the byproduct
of its doing so.
The stumbling-block for this sort of suggestion is that the mind is much
more systematic than the world: that John loves Mary doesn’t make it true,
or even very likely, that Mary reciprocates. Sad for John, of course, but
where would The Western Canon be if things were otherwise? In fact, the
only thing in the world that is as systematic as thought is language.
Accordingly, some philosophers (Dan Dennett 1993 in particular) have
suggested that it’s learning language that makes a mind systematic.
But we aren’t told how an initially unsystematic mind could learn a
systematic language, given that the latter is ipso facto able to express
propositions that the former is unable to entertain. How, for example, does
a mind that can think that John loves Mary but not that Mary loves John
learn a language that is able to say both? Nor is it clear what could make
language itself systematic if not the systematicity of the thoughts that it is
used to express; so the idea that the mind learns systematicity from
language just sweeps the problem from under the hall rug to under the
rug in the parlour. On balance, I think we had better take it for granted,
2 It bears emphasis that systematicity concerns symmetries of cognitive capacities, not
of actual mental states. It is, for example, patently not the case that whoever thinks that
Mary loves John also thinks that John loves Mary. Compare van Gelder and Nicklasson
1994.
and as part of what is not negotiable, that systematicity and productivity
are grounded in the ‘architecture’ of mental representation and not in the
vagaries of experience. If a serious alternative proposal should surface, I
guess I’m prepared to reconsider what’s negotiable. But the prospect hasn’t
been losing me sleep.
So, to repeat the question, what is it about mental representation that
explains the systematicity and productivity of belief ? Classical versions
of RTM offer a by now familiar answer: there are infinitely many beliefs
because there are infinitely many thoughts to express their objects. There
are infinitely many thoughts because, though each mental representation
is constructed by the application of a finite number of operations to a
finite basis of primitive concepts, there is no upper bound to how many
times such operations may apply in the course of a construction.
Correspondingly, thought is systematic because the same primitive
concepts and operations that suffice to assemble thoughts like JOHN
LOVES MARY also suffice to assemble thoughts like MARY LOVES
JOHN; the representational capacity that is exploited to frame one
thought implies the representational capacity to frame the other. Since a
mental representation is individuated by its form and content (see
Chapter 1), both of these are assumed to be determined by specifying the
inventory of primitive concepts that the representation contains, together
with the operations by which it is assembled from them. (In the case of the
primitive concepts themselves, this assumption is trivially true.) As a
shorthand for all this, I’ll say that what explains the productivity and
systematicity of the propositional attitudes is the compositionality of
concepts and thoughts.
The requirement that the theory of mental representation should
exhibit thoughts and concepts as compositional turns out, in fact, to be
quite a powerful analytic engine. If the content of a mental representation
is inherited from the contents of its conceptual constituents then, presumably,
the content of a constituent concept is just whatever it can
contribute to the content of its hosts. We’ll see, especially in Chapter 5,
that this condition is not at all easy for a theory of concepts to meet.
4. Quite a lot of concepts must turn out to be learned.
I want to put this very roughly since I’m going to return to it at length
in Chapter 6. Suffice it for now that all versions of RTM hold that if a
concept belongs to the primitive basis from which complex mental
representations are constructed, it must ipso facto be unlearned. (To be
sure, some versions of RTM are rather less up front in holding this than
others.) Prima facie, then, where a theory of concepts draws the distinction
between what’s primitive and what’s not is also where it draws the
What Concepts Have To Be 27
28 Unphilosophical Introduction
distinction between what’s innate and what’s not. Clearly, everybody is
going to put this line somewhere. For example, nobody is likely to think
that the concept BROWN COW is primitive since, on the face of it,
BROWN COW has BROWN and COW as constituents. Correspondingly,
nobody is likely to think that the concept BROWN COW is innate since,
on the face of it, it could be learned by being assembled from the
previously mastered concepts BROWN and COW.
A lot of people have Very Strong Feelings about what concepts are
allowed to be innate,3 hence about how big a primitive conceptual basis an
acceptable version of RTM can recognize. Almost everybody is prepared
to allow RED in, and many of the liberal-minded will also let in CAUSE
or AGENT. (See, for example, Miller and Johnson-Laird 1978). But there
is, at present, a strong consensus against, as it might be, DOORKNOB or
CARBURETTOR. I have no desire to join in this game of pick and
choose since, as far as I can tell, it hasn’t any rules. Suffice it that it would
be nice if a theory of concepts were to provide a principled account of
what’s in the primitive conceptual basis, and it would be nice if the
principles it appealed to were to draw the distinction at some
independently plausible place. (Whatever, if anything, that means.)
Chapter 6 will constitute an extended reconsideration of this whole issue,
including the question just how the relation between a concept’s being
primitive and its being innate plays out. I hope there to placate such
scruples about DOORKNOB and CARBURETTOR as some of you may
feel, and to do so within the framework of an atomistic RTM.
5. Concepts are public; they’re the sorts of things that lots of people
can, and do, share.
Since, according to RTM, concepts are symbols, they are presumed to
satisfy a type/token relation; to say that two people share a concept (i.e.
that they have literally the same concept) is thus to say that they have
tokens of literally the same concept type. The present requirement is that
the conditions for typing concept tokens must not be so stringent as to
assign practically every concept token to a different type from practically
any other.
3 I put it this way advisedly. I was once told, in the course of a public discussion with
an otherwise perfectly rational and civilized cognitive scientist, that he “could not permit”
the concept HORSE to be innate in humans (though I guess it’s OK for it to be innate in
horses). I forgot to ask him whether he was likewise unprepared to permit neutrinos to lack
mass.
Just why feelings run so strongly on these matters is unclear to me.Whereas the ethology
of all other species is widely agreed to be thoroughly empirical and largely morally neutral,
a priorizing and moralizing about the ethology of our species appears to be the order of the
day. Very odd.

What Concepts Have To Be 29

It seems pretty clear that all sorts of concepts (for example, DOG,
FATHER, TRIANGLE, HOUSE, TREE, AND, RED, and, surely, lots
of others) are ones that all sorts of people, under all sorts of circumstances,
have had and continue to have. A theory of concepts should set
the conditions for concept possession in such a way as not to violate this
intuition. Barring very pressing considerations to the contrary, it should
turn out that people who live in very different cultures and/or at very
different times (me and Aristotle, for example) both have the concept
FOOD; and that people who are possessed of very different amounts of
mathematical sophistication (me and Einstein, for example) both have the
concept TRIANGLE; and that people who have had very different kinds
of learning experiences (me and Helen Keller, for example) both have the
concept TREE; and that people with very different amounts of knowledge
(me and a four-year-old, for example) both have the concept HOUSE.
And so forth. Accordingly, if a theory or an experimental procedure
distinguishes between my concept DOG and Aristotle’s, or between my
concept TRIANGLE and Einstein’s, or between my concept TREE and
Helen Keller’s, etc. that is a very strong prima facie reason to doubt that
the theory has got it right about concept individuation or that the
experimental procedure is really a measure of concept possession.
I am thus setting my face against a variety of kinds of conceptual
relativism, and it may be supposed that my doing so is itself merely
dogmatic. But I think there are good grounds for taking a firm line on this
issue. Certainly RTM is required to. I remarked in Chapter 1 that RTM
takes for granted the centrality of intentional explanation in any viable
cognitive psychology. In the cases of interest, what makes such
explanations intentional is that they appeal to covering generalizations
about people who believe that such-and-such, or people who desire that
so-and-so, or people who intend that this and that, and so on. In
consequence, the extent to which an RTM can achieve generality in the
explanations it proposes depends on the extent to which mental contents
are supposed to be shared. If everybody else’s concept WATER is different
from mine, then it is literally true that only I have ever wanted a drink of
water, and that the intentional generalization ‘Thirsty people seek water’
applies only to me. (And, of course, only I can state that generalization;
words express concepts, so if your WATER concept is different from mine,
‘Thirsty people seek water’ means something different when you say it and
when I do.) Prima facie, it would appear that any very thoroughgoing
conceptual relativism would preclude intentional generalizations with any
very serious explanatory power. This holds in spades if, as seems likely, a
coherent conceptual relativist has to claim that conceptual identity can’t
be maintained even across time slices of the same individual.
What Concepts Have To Be 29
30 Unphilosophical Introduction
There is, however, a widespread consensus (and not only among
conceptual relativists) that intentional explanation can, after all, be
preserved without supposing that belief contents are often—or even
ever—literally public. The idea is that a robust notion of content similarity
would do just as well as a robust notion of content identity for the
cognitive scientist’s purposes. Here, to choose a specimen practically at
random, is a recent passage in which Gil Harman enunciates this faith:
Sameness of meaning from one symbol system to another is a similarity relation
rather than an identity relation in the respect that sameness of meaning is not
transitive . . . I am inclined to extend the point to concepts, thoughts, and
beliefs . . . The account of sameness of content appeals to the best way of
translating between two systems, where goodness in translation has to do with
preserving certain aspects of usage, with no appeal to any more ‘robust’ notion of
content or meaning identity . . . [There’s no reason why] the resulting notion of
sameness of content should fail to satisfy the purposes of intentional explanation.
(1993: 169–79)4
It’s important whether such a view can be sustained since, as we’ll see,
meeting the requirement that intentional contents be literally public is
non-trivial; like compositionality, publicity imposes a substantial
constraint upon one’s theory of concepts and hence, derivatively, upon
one’s theory of language. In fact, however, the idea that content similarity
is the basic notion in intentional explanation is affirmed a lot more widely
than it’s explained; and it’s quite unclear, on reflection, how the notion of
similarity that such a semantics would require might be unquestionbeggingly
developed. On one hand, such a notion must be robust in the
sense that it preserves intentional explanations pretty generally; on the
other hand, it must do so without itself presupposing a robust notion of
content identity. To the best of my knowledge, it’s true without exception
that all the construals of concept similarity that have thus far been put on
offer egregiously fail the second condition.
Harman, for example, doesn’t say much more about content-similaritycum-
goodness-of-translation than that it isn’t transitive and that it
“preserves certain aspects of usage”. That’s not a lot to go on. Certainly
it leaves wide open whether Harman is right in denying that his account
of content similarity presupposes a “‘robust’ notion of content or meaning
identity”. For whether it does depends on how the relevant “aspects of
4 See also Smith, Medin, and Rips: “what accounts for categorization cannot account
for stability [publicity] . . . [a]s long as stability of concepts is equated with sameness of
concepts . . . But there is another sense of stability, which can be equated with similarity of
mental contents . . . and for this sense, what accounts for categorization may at least partially
account for ‘stability’ ”(1984: 268). Similar passages are simply ubiquitous in the cognitive
science literature; I’m grateful to Ron Mallon for having called this example to my attention.
usage” are themselves supposed to be individuated, and about this we’re
told nothing at all.
Harman is, of course, too smart to be a behaviourist; ‘usage’, as he uses
it, is itself an intentional-cum-semantic term. Suppose, what surely seems
plausible, that one of the ‘aspects of usage’ that a good translation of ‘dog’
has to preserve is that it be a term that implies animal, or a term that
doesn’t apply to ice cubes, or, for matter, a term that means dog. If so,
then we’re back where we started; Harman needs notions like same
implication, same application, and same meaning in order to explicate his
notion of content similarity. All that’s changed is which shell the pea is
under.
At one point, Harman asks rhetorically, “What aspects of use
determine meaning?” Reply: “It is certainly relevant what terms are
applied to and the reasons that might be offered for this application . . . it
is also relevant how some terms are used in relation to other terms” (ibid.:
166). But I can’t make any sense of this unless some notion of ‘same
application’, ‘same reason’, and ‘same relation of terms’ is being taken for
granted in characterizing what good translations ipso facto have in
common. NB on pain of circularity: same application (etc.), not similar
application (etc.). Remember that similarity of semantic properties is the
notion that Harman is trying to explain, so his explanation mustn’t
presuppose that notion.
I don’t particularly mean to pick on Harman; if his story begs the
question it was supposed to answer, that is quite typical of the literature
on concept similarity. Though it’s often hidden in a cloud of technical
apparatus (for a detailed case study, see Fodor and Lepore 1992: ch. 7), the
basic problem is easy enough to see. Suppose that we want the following
to be a prototypical case where you and I have different but similar
concepts of George Washington: though we agree about his having been
the first American President, and the Father of His Country, and his
having cut down a cherry tree, and so on, you think that he wore false
teeth and I think that he didn’t. The similarity of our GW concepts is thus
some (presumably weighted) function of the number of propositions
about him that we both believe, and the dissimilarity of our GW concepts
is correspondingly a function of the number of such propositions that we
disagree about. So far, so good.
But the question now arises: what about the shared beliefs themselves;
are they or aren’t they literally shared? This poses a dilemma for the
similarity theorist that is, as far as I can see, unavoidable. If he says that
our agreed upon beliefs about GW are literally shared, then he hasn’t
managed to do what he promised; viz. introduce a notion of similarity of
content that dispenses with a robust notion of publicity. But if he says

32 Unphilosophical Introduction

2 Unphilosophical Introduction
that the agreed beliefs aren’t literally shared (viz. that they are only
required to be similar), then his account of content similarity begs the
very question it was supposed to answer: his way of saying what it is for
concepts to have similar but not identical contents presupposes a prior
notion of beliefs with similar but not identical contents.
The trouble, in a nutshell, is that all the obvious construals of similarity
of beliefs (in fact, all the construals that I’ve heard of) take it to involve
partial overlap of beliefs.5 But this treatment breaks down if the beliefs
that are in the overlap are themselves construed as similar but not
identical. It looks as though a robust notion of content similarity can’t
but presuppose a correspondingly robust notion of content identity.
Notice that this situation is not symmetrical; the notion of content identity
doesn’t require a prior notion of content similarity. Leibniz’s Law tells us
what it is for the contents of concepts to be identical; Leibniz’s Law tells
us what it is for anythings to be identical.
As I remarked above, different theorists find different rugs to sweep this
problem under; but, as far as I can tell, none of them manages to avoid it.
I propose to harp on this a bit because confusion about it is rife, not just
in philosophy but in the cognitive science community at large. Not getting
it straight is one of the main things that obscures how very hard it is to
construct a theory of concepts that works, and how very much cognitive
science has thus far failed to do so.
Suppose, for example, it’s assumed that your concept PRESIDENT is
similar to my concept PRESIDENT in so far as we assign similar
subjective probabilities to propositions that contain the concept. There
are plenty of reasons for rejecting this sort of model; we’ll discuss its main
problems in Chapter 5. Our present concern is only whether constructing
a probabilistic account of concept similarity would be a way to avoid
having to postulate a robust notion of content identity.
Perhaps, in a typical case, you and I agree that p is very high for ‘FDR
is/was President’ and for ‘The President is the Commander-in-Chief of
the Armed Forces’ and for ‘Presidents have to be of voting age’, etc.; but,
whereas you rate ‘Millard Fillmore is/was President’ as having a
probability close to 1, I, being less well informed, take it to be around
p = 0.07 (Millard Fillmore???). This gives us an (arguably) workable
construal of the idea that we have similar but not identical PRESIDENT
concepts. But it does so only by helping itself to a prior notion of belief
identity, and to the assumption that there are lots of thoughts of which
5 ‘Why not take content similarity as primitive and stop trying to construe it?’ Sure; but
then why not take content identity as primitive and stop trying to construe it? In which
case, what is semantics for?
What Concepts Have To Be 33
our respective PRESIDENTs are constituents that we literally share. Thus,
you and I are, by assumption, both belief-related to the thoughts that
Millard Fillmore was President, that Presidents are Commanders-in-Chief,
etc. The difference between us is in the strengths of our beliefs, not in their
contents.6 And, as usual, it really does seem to be identity of belief content
that’s needed here. If our respective beliefs about Presidents having to be
of voting age were supposed to be merely similar, circularity would ensue:
since content similarity is the notion we are trying to explicate, it mustn’t
be among the notions that the explication presupposes. (I think I may have
mentioned that before.)
The same sort of point holds, though even more obviously, for other
standard ways of construing conceptual similarity. For example, if
concepts are sets of features, similarity of concepts will presumably be
measured by some function that is sensitive to the amount of overlap of
the sets. But then, the atomic feature assignments must themselves be
construed as literal. If the similarity between your concept CAT and mine
depends (inter alia) on our agreement that ‘+ has a tail’ is in both of our
feature bundles, then the assignment of that feature to these bundles must
express a literal consensus; it must literally be the property of having a tail
that we both literally think that cats literally have. (As usual, nothing
relevant changes if feature assignments are assumed to be probabilistic or
weighted; or if the feature assigned are supposed to be “subsemantic”,
though these red herrings are familiar from the Connectionist literature.)
Or, suppose that concepts are thought of as positions in a “multidimensional
vector space” (see e.g. Churchland 1995) so that the similarity
between your concepts and mine is expressed by the similarity of their
positions in our respective spaces. Suppose, in particular, that it is
constitutive of the difference between our NIXON concepts that you think
Nixon was even more of a crook than I do. Once again, a robust notion
of content identity is presupposed since each of our spaces is required to
have a dimension that expresses crookedness; a fortiori, both are required
6 Alternatively, a similarity theory might suppose that what we share when our
PRESIDENT concepts are similar are similar beliefs about the probabilities of certain
propositions: you believe that p(presidents are CICs) = 0.98; I believe that p(presidents are
CICs) = 0.95; Bill believes that p(Presidents are CICs) = 0.7; so, all else equal, your
PRESIDENT concept is more like mine than Bill’s is.
But this construal does nothing to discharge the basic dependence of the notion of
content similarity on the notion of content identity since what it says makes our beliefs
similar is that they make similar estimates of the probability of the very same proposition;
e.g. of the proposition that presidents are CICs. If, by contrast, the propositions to which
our various probability estimates relate us are themselves supposed to be merely similar, then
it does not follow from these premisses that ceteris paribus your PRESIDENT concept is
more like mine than like Bill’s.
to have dimensions which express degrees of the very same property. That
should seem entirely unsurprising. Vector space models identify the
dimensions of a vector space semantically (viz. by stipulating what the
location of a concept along that dimension is to mean), and it’s just a
truism that the positions along dimension D can represent degrees of Dness
only in a mind that possesses the concept of being D. You and I can
argue about whether Nixon was merely crooked or very crooked only if the
concept of being crooked is one that we have in common.
It may seem to you that I am going on about such truisms longer than
necessity demands. It often seems that to me, too. There are, however, at
least a zillion places in the cognitive science literature, and at least half a
zillion in the philosophy literature, where the reader is assured that some
or all of his semantical troubles will vanish quite away if only he will
abandon the rigid and reactionary notion of content identity in favour of
the liberal and laid-back notion of content similarity. But in none of these
places is one ever told how to do so. That’s because nobody has the
slightest idea how. In fact, it’s all just loose talk, and it causes me to grind
my teeth.
Please note that none of this is intended to claim that notions like belief
similarity, content similarity, concept similarity, etc. play less than a central
role in the psychology of cognition. On the contrary, for all I know
(certainly for all I am prepared non-negotiably to assume) it may be that
every powerful intentional generalization is of the form “If x has a belief
similar to P, then . . .” rather than the form “If x believes P, then . . .”. If
that is so, then so be it. My point is just that assuming that it is so doesn’t
exempt one’s theory of concepts from the Publicity constraint. To repeat
one last time: all the theories of content that offer a robust construal of
conceptual similarity do so by presupposing a correspondingly robust
notion of concept identity. As far as I can see, this is unavoidable. If I’m
right that it is, then the Publicity constraint is ipso facto non-negotiable.
OK, so those are my five untendentious constraints on theories of
concepts. In succeeding chapters, I’ll consider three stories about what
concepts are; viz. that they are definitions; that they are prototypes/
stereotypes; and (briefly) something called the ‘theory theory’ which says,
as far as I can make out, that concepts are abstractions from belief
systems. I’ll argue that each of these theories violates at least one of the
non-negotiable constraints; and that it does so, so to speak, not a little bit
around the edges but egregiously and down the middle.We will then have
to consider what, if any, options remain for developing a theory of
concepts suitable to the purposes of an RTM.
Before we settle down to this, however, there are a last couple of preliminary
points that I want to put in place.