44 The Demise of Definitions, Part I

evaluable (for soundness, validity, reliability, etc.), defining inferences are
semantically evaluable inter alia.
—Publicity is satisfied since there’s no obvious reason why lots of
people might not assign the same defining inferences to a given word or
concept. They might do so, indeed, even if there are lots of differences in
what they know/believe about the things the concept applies to (lots of
differences in the ‘collateral information’ they have about such things).
—Compositionality is satisfied. This will bear emphasis later. I’m going
to argue that, of the various ‘inferential role’ theories of concepts, only the
one that says that concepts are definitions meets the compositionality
condition. Suffice it for now that words/concepts do contribute their
definitions to the sentences/thoughts that contain them; it’s part and parcel
of ‘bachelor’ meaning unmarried man that the sentence ‘John is a bachelor’
means John is an unmarried man and does so because it has ‘bachelor’
among its constituents. To that extent, at least, definitions are in the
running to be both word meanings and conceptual contents.
—Learnability is satisfied. If the concept DOG is a definition, then
learning the definition should be all that’s required to learn the concept. A
fortiori, concepts that are definitions don’t have to be innate.
To be sure, learning definitions couldn’t be the whole story about
acquiring concepts. Not all concepts could be definitions, since some have
to be the primitives that the others are defined in terms of; about the
acquisition of the primitive concepts, some quite different story will have
to be told. What determines which concepts are primitive was one of the
questions that definition theories never really resolved. Empiricists in
philosophy wanted the primitive concepts to be picked out by some
epistemological criterion; but they had no luck in finding one. (For
discussion of these and related matters, see Fodor 1981a, 1981b.) But,
however exactly this goes, the effect of supposing that there are definitions
is to reduce the problems about concepts at large to the corresponding
problems about primitive concepts. So, if some (complex) concept C is
defined by primitive concepts c1, c2, . . ., then explaining how we acquire
C reduces to explaining how we acquire c1, c2, . . . And the problem of how
we apply C to things that fall under it reduces to the problem of how we
apply c1, c2, . . . to the things that fall under them. And explaining how we
reason with C reduces to explaining how we reason with c1, c2, . . . And so
forth. So there is good work for definitions to do if there turn out to be
any.
All the same, these days almost nobody thinks that concepts are
definitions. There is now something like a consensus in cognitive science
that the notion of a definition has no very significant role to play in
theories of meaning. It is, to be sure, a weakish argument against
44 The Demise of Definitions, Part I
definitions that most cognitive scientists don’t believe in them. Still, I do
want to remind you how general, and how interdisciplinary, the collapse
of the definitional theory of content has been. So, here are some reasons
why definitions aren’t currently in favour as candidates for concepts (/word
meanings):
—There are practically no defensible examples of definitions; for all
the examples we’ve got, practically all words (/concepts) are undefinable.
And, of course, if a word (/concept) doesn’t have a definition, then its
definition can’t be its meaning. (Oh well, maybe there’s one definition.
Maybe BACHELOR has the content unmarried man. Maybe there are
even six or seven definitions; why should I quibble? If there are six or seven
definitions, or sixty or seventy, that still leaves a lot of words/concepts
undefined, hence a lot of words/concepts of which the definitional theory
of meaning is false. The OED lists half a million words, plus or minus a
few.)
Ray Jackendoff has suggested that the reason natural language contains
so few phrases that are definitionally equivalent to words is that there are
“nondiscrete elements of concepts . . . [which] play a role only in lexical
semantics and never appear as a result of phrasal combination” (1992:
48). (I guess that “nondiscrete” means something like analogue or iconic.)
But this begs the question that it’s meant to answer, since it simply assumes
that that there are contents that only nondiscrete symbols can express.
Notice that you don’t need nondiscrete symbols to express nondiscrete
properties. ‘Red’ does quite a good job of expressing red. So suppose there
is something essentially nondiscrete about the concepts that express lexical
meanings. Still, it wouldn’t follow that the same meanings can’t be
expressed by phrases. So, even if nondiscrete elements of concepts never
appear as a result of phrasal combination, that still wouldn’t explain why
most words can’t be defined.
—It’s a general problem for theories that seek to construe content in
terms of inferential role, that there seems to be no way to distinguish the
inferences that constitute concepts from other kinds of inferences that
concepts enter into. The present form of this general worry is that there
seems to be no way to distinguish the inferences that define concepts from
the ones that don’t. This is, of course, old news to philosophers. Quine
shook their faith that ‘defining inference’ is well defined, and hence their
faith in such related notions as analyticity, propositions true in virtue of
meaning alone, and so forth. Notice, in particular, that there are grounds
for scepticism about defining inferences even if you suppose (as, of course,
Quine does not) that the notion of necessary inference is secure.What’s at
issue here is squaring the theory of concept individuation with the theory
of concept possession. If having a concept requires accepting the
The Linguist’s Tale 45
inferences that define it, then not all necessities can be definitional. It is, for
example, necessary that 2 is a prime number; but surely you can have the
concept 2 and not have the concept of a prime; presumably there were
millennia when people did. (Similarly, mutatis mutandis, for the concept
WATER if it’s necessary that water is H2O. I’ll come back to this sort of
point in Chapter 4.)
It is often, and rightly, said that Quine didn’t prove that you can’t make
sense of analyticity, definition, and the like. But so what? Cognitive science
doesn’t do proofs; it does empirical, non-demonstrative inferences. We
have, as things now stand, no account of what makes an inference a
defining one, and no idea how such an account might be devised. That’s a
serious reason to suppose that the theory of content should dispense with
definitions if it can.
—Although in principle definitions allow us to reduce all sorts of
problems about concepts at large to corresponding problems about
concepts in the primitive basis (see above), this strategy quite generally
fails in practice. Even if there are definitions, they seem to play no very
robust role in explaining what happens when people learn concepts, or
when they reason with concepts, or when they apply them. Truth to tell,
definitions seem to play no role at all.
For example, suppose that understanding a sentence involves recovering
and displaying the definitions of the words that the sentence contains.
Then you would expect, all else equal, that sentences that contain words
with relatively complex definitions should be harder to understand than
sentences that contain words with relatively simple definitions. Various
psychologists have tried to get this effect experimentally; to my knowledge,
nobody has ever succeeded. It’s an iron law of cognitive science that, in
experimental environments, definitions always behave exactly as though
they weren’t there.
In fact, this is obvious to intuition. Does anybody present really think
that thinking BACHELOR is harder than thinking UNMARRIED? Or
that thinking FATHER is harder than thinking PARENT? Whenever
definition is by genus and species, definitional theories perforce predict
that concepts for the former ought to be easier to think than concepts for
the latter. Intuition suggests otherwise (and so, by the way, do the
experimental data; see e.g. Paivio 1971).
Hold-outs for definitions often emphasize that the experimental failures
don’t prove that there aren’t any definitions. Maybe there’s a sort of
novice/expert shift in concept acquisition: (defining) concepts like
UNMARRIED MAN get ‘compiled’ into (defined) concepts like
BACHELOR soon after they are mastered. If experiments don’t detect
UNMARRIED MAN in ‘performance’ tasks, maybe that’s because
46 The Demise of Definitions, Part I
BACHELOR serves as its abbreviation.4 Maybe. But I remind you, once
again, that this is supposed to be science, not philosophy; the issue isn’t
whether there might be definitions, but whether, on the evidence, there
actually are some. Nobody has proved that there aren’t any little green
men on Mars; but almost everybody is convinced by repeated failures to
find them.
Much the same point holds for the evidence about concept learning.
The (putative) ontogenetic process of compiling primitive concepts into
defined ones surely can’t be instantaneous; yet developmental cognitive
psychologists find no evidence of a stage when primitive concepts exist
uncompiled. I appeal to expert testimony; here’s Susan Carey concluding
a review of the literature on the role of definitions (‘conceptual decompositions’,
as one says) in cognitive development: “At present, there simply is
no good evidence that a word’s meaning is composed, component by
component, in the course of its acquisition. The evidence for componentby-
component acquisition is flawed even when attention is restricted to
those semantic domains which have yielded convincing componential
analyses” (1982: 369). (I reserve the right to doubt that there are any such
domains; see below.)
So it goes. Many psychologists, like many philosophers, are now very
sceptical about definitions. This seems to be a real case of independent
lines of enquiry arriving at the same conclusions for different but
compatible reasons. The cognitive science community, by and large, has
found this convergence pretty persuasive, and I think it’s right to do so.
Maybe some version of inferential role semantics will work and will
sustain the thesis that most everyday concepts are complex; but, on the
evidence, the definitional version doesn’t.
I’d gladly leave it here if I could, but it turns out there are exceptions to
the emerging consensus that I’ve been reporting. Some linguists, working
in the tradition called ‘lexical semantics’, claim that there is persuasive
distributional (/intuitional) evidence for a level of linguistic analysis at
which many words are represented by their definitions. It may be, so the
argument goes, that these linguistic data don’t fit very well with the results
in philosophy and psychology; if so, then that’s a problem that cognitive
scientists should be worrying about. But, assuming that you’re prepared to
take distributional/intuitional data seriously at all (as, no doubt, you
The Linguist’s Tale 47
4 I am playing very fast and loose with the distinction between concepts and their
structural descriptions (see n. 1 above). Strictu dictu, it can’t both be that the concept
BACHELOR abbreviates the concept UNMARRIED MAN and that the concept
BACHELOR is the concept UNMARRIED MAN. But not speaking strictly makes the
exposition easier, and the present considerations don’t depend on the conflation.