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.