118 Prototypes and Compositionality

“coherence” of concepts, but it’s far from clear what they think conceptual
coherence is. At one point, having suggested that the theory theory should
provide “guidelines concerning which combinations of features form
possible concepts and which form coherent ones” (1987: 30), they offer, as
an example of an incoherent concept, “bright red, flammable, eats
mealworms, found in Lapland, and used for cleaning furniture”. So it
sounds as though the question about conceptual coherence that the theory
theory answers is: What’s wrong with this and other such concepts?
But it’s hard to believe that is the question since the answer, though
perfectly obvious and entirely banal, is one that Medin and Wattenmaker
don’t even consider. What’s wrong with the concept BRIGHT RED,
FLAMMABLE, EATS MEALWORMS, . . . etc. is that, as far as anybody
knows, there’s nothing that is, or would be, true of things in virtue of their
falling under it (except what follows trivially from their falling under it; e.g.
that they are, or would be, found in Lapland). In particular, there are no
substantive, counterfactual-supporting generalizations about such things;
so why on earth would anybody want to waste his time thinking about
them? Compare such unsatisfied (but coherent) concepts as UNICORN.
At least there’s a story about unicorns. That is, there are interesting things
that are supposed to be true about them: that their ground-up horns are
antidotes to many poisons; that if there were unicorns, virgins could catch
them if there were virgins, and so on. In short, such examples as Medin
and Wattenmaker offer suggest that being ‘coherent’ isn’t even a
psychological property: the incoherence of BRIGHT RED, FLAMMABLE,
. . . etc. is a defect not of the concept but of the world. It’s
therefore hard to see why a psychologist should care about it (though
perhaps a zoologist might).
Or perhaps Medin and Wattenmaker have some other construal of
conceptual coherence in mind; but search me what it is.26
To return to the main theme: many of the typical preoccupations of
theory theorists seem to be largely neutral on the issue of concept
118 Prototypes and Compositionality
26 See also Keil: “Prototypes merely represent correlated properties, they offer no
explanation of the reasons for those correlations (e.g. why the prototypical features of birds,
such as beaks, feathers, and eggs tend to co-occur)” (1987: 195). The suggestion seems to be
that the difference between prototype theories and theory theories is that the latter entail
that having a concept involves knowing the explanation of such correlations (or knowing
that there is an explanation? or knowing that some expert knows the explanation?). But, if
so, it seems that theory theories set the conditions for concept possession impossibly high.
I’m pretty confident that being liquid and transparent at room temperature are correlated
properties of water. But I have no idea why they are correlated. Notice, in particular, that
learning that being water is being H2O didn’t advance my epistemic situation in this respect
since I don’t know why being liquid and transparent at room temperature are correlated
properties of H2O. Do you?
individuation—Is conceptual change discontinuous? What makes a
concept coherent? Are children metaphysical essentialists?—and the like.
There is, to be sure, much that’s of interest to be said on these topics. But,
thank Heaven, not here. From our point of view, the crucial question is
whether, when a theory theorist says that concepts are typically embedded
in theoretical inferences, he means to claim that knowing (some or all) of
the theory is a necessary condition for having the concept. If yes, then the
‘which inferences’ question has to be faced. If no, then some positive
account of concept possession/individuation is owing. The definition story
and the prototype story are bona fide competing theories of concepts
because they do have answers to such questions on offer. As far as I can
make out, the theory theory doesn’t, so it isn’t.