Natural Kinds Come Late
I think natural kind concepts have been getting more of a press than they deserve of late. It’s past time to put them in their place; and their place is that of self-conscious and cultivated intellectual achievements. Much of what is currentlybeing written about concepts—by philosophers, but also, increasingly, by psychologists—suggests that natural kindconcepts are the paradigms on which we should model our accounts of concept acquisition and concept possession atlarge. This is, I think, hopeless on the face of it. For one thing, as Putnam in particular has argued, natural kindconcepts thrive best—maybe only—in an environment where conventions of deference to experts are in place. But,patently, only creatures with an antecedently complex mental life could make a policy of adherence to such conventions.Adherence to conventions of deference couldn’t be a precondition for conceptual content in general, if only becausedeference has to stop somewhere; if my ELM concept is deferential, that’s because the botanist’s isn’t. Anyhow, it seemsjust obvious that concepts like STAR in, as one says, the ‘technical sense’—the concept of stars that is prepared todefer about the Sun and black dwarfs on the one hand and meteors and comets on the other—come after, andsometimes come to replace, their colloquial counterparts.
As I say, this view flies in the face of the current fashions in developmental cognitive psychology, which stress how early, and how universally, natural kind concepts are available to children. But I find that I’m not much convinced.There is, to be sure, getting to be a lot of evidence (contra Piaget) that young children are deeply into appearance/reality distinctions: they’re clear that you can’t make a horse into a zebra just by painting on stripes (Keil 1989); andthey’re clear that, for some categories (animals but not vases, for example), what’s on the inside matters to what kind athing belongs to (Carey 1985). It’s usual to summarize such findings as showing that young children are ‘essentialists’,and if you like to talk that way, so be it.5 My point, however, is that being an essentialist in this sense clearly does notimply having natural kind concepts; not even if a cognitivist picture of concept possession is assumed for sake of theargument. What’s further required, at a minimum, is the idea that what’s ‘inside’ (or otherwise hidden) somehow iscausally responsible for how
things that belong to the kind appear; for their ‘superficial signs’. It is, of course, an empirical issue, but I don’t know of any evidence that children think that sort of thing.
If it’s easy to miss the extent to which natural kind concepts are sophisticated achievements, that’s perhaps because of a nasty ambiguity in the term. (One that we’ve already encountered, in fact; it’s why I had to pussyfoot about whetherthey had WATER in the Garden). Consider this dialectic:
—Did Homer have natural kind concepts?
Sure, he had the concept WATER (and the like), and water is a natural kind.
—Did Homer have natural kind concepts?
Of course not. He had no disposition to defer to experts about water (and the like); I expect the notion of an expert about water would have struck him as bizarre. And, of course Homer had no notion that water has ahidden essence, or a characteristic microstructure (or that anything else does); a fortiori, he had no notion thatthe hidden essence of water is causally responsible for its phenomenal properties.
A ‘natural kind concept’ can be the concept of a natural kind; or it can be the concept of a natural kind as such (i.e. the concept of a natural kind as a natural kind). It‘s perfectly consistent to claim that Homer had plenty of the first butnone of the second. In fact, I think that’s pretty clearly true. So the suggestion is that, in the history of science, and inontogeny, and, for all I know, in phylogeny too, concepts of natural kinds as such only come late. Homer, and children,and animals, have few of them or none. Somehow, concepts of natural kinds as such emerge from a background ofconcepts of mind-dependent properties, and of concepts of natural kinds that aren’t concepts of natural kinds as such.Presumably it’s because they do somehow emerge from a background of other kinds of concepts that concepts ofnatural kind as such don’t have to be innate.