APPENDIX 6A

APPENDIX 6A
Similarity
‘Hey, aren’t you just saying that all that has to be innate in a DOORKNOBacquisition
device is the capacity to learn to respond selectively to things
that are relevantly similar to doorknobs? And didn’t Quine say that years
ago?’
No, I’m not and no, he didn’t. Not quite.
There are two ways to understand the claim that the process of
acquiring DOORKNOB recruits an innate ‘similarity metric’. One is
platitudinous, the other is committed to innate ideas—in effect, to the
innateness of the concept SIMILAR TO A DOORKNOB. The geography
around here is pretty familiar, so we can settle for a quick tour.
On the first way of running it, the similarity story is just the remark
that, given appropriate experience of doorknobs, creatures like us converge
on a capacity to respond selectively to things that are like doorknobs in
respect of their doorknobhood. This is perfectly self-evidently true; nobody
reasonable could wish to deny it. It doesn’t, however, explain the fact that
we learn DOORKNOB from doorknobs; it just repeats the fact that we do.
So construed, the similarity story is completely neutral on the issues this
chapter is concerned with, viz. whether the structures in virtue of which we
are able to converge on selective sensitivity to doorknobhood need to be
innate, and whether they need to be intentional.
On the other, unplatitudinous, way of running the similarity theory, it
is itself a version of concept nativism: it’s the thesis that what’s innate is
the concept SIMILAR TO A DOORKNOB. There seems, to put it mildly,
to be no reason to prefer that view to one that has DOORKNOB itself be
innate. (Indeed, the first would seem to imply the second; since the concept
SIMILAR TO A DOORKNOB is, on the face of it, a construct out of the
concept DOORKNOB, it’s hard to imagine how anyone could think the
one concept unless he could also think the other.) None of this bothers
Quine much, of course, because he pretty explicitly assumes the Empiricist
principle that the innate dimensions of similarity, along which experience
generalizes, are sensory. But Empiricism isn’t true, and it is time to put
away childish things.
Quine’s story is that learning DOORKNOB is learning to respond
selectivity to things that are similar to doorknobs.What the story amounts
to depends, in short, on how being similar to doorknobs is construed.Well,
there’s a dilemma: if being similar to doorknobs is elucidated by appeal to
doorknobhood, then the story is patently empty; ‘How is the concept that
expresses doorknobhood acquired?’ is the very question that it was
supposed to be the answer to. If, on the other hand, being similar to
The Standard Argument 145
doorknobs is spelled out by reference to properties other than
doorknobhood, Quine has to say which properties these are, where the
concepts of these properties come from, and how radical nativism with
respect to them is to be avoided.
Like Quine, I’ve opted for the second horn of the dilemma. But, unlike
Quine, I’m no Empiricist. Accordingly, I can appeal to the doorknob
stereotype to say what ‘similarity to doorknobs’ comes to, and—since ‘the
doorknob stereotype’ is independently defined—I can do so without
invoking the concept DOORKNOB and thereby courting platitude.
So I’m not saying what Quine said; though it may well be what he
should have said, and would have said but for his Empiricism. I often have
the feeling that I’m just saying what Quine would have said but for his
Empiricism.18
18 I am also, unlike Quine, not committed to construing locking in terms of a capacity
for discriminated responding (or, indeed, of anything epistemological). Locking reduces to
nomic connectedness. (I hope.) See Fodor 1990; Fodor forthcoming b.