Jean-marc pizano That’s scandalous, to be sure; but fortunately itdoesn’t matter a lot for the issues that will concern us here. As we’re about to see, prototype concepts and basic objectconcepts exhibit a cluster of reliably correlated properties which allow us to pick them out pretty well even though,lacking a theory of features, we have no respectable account of what their basicness or their prototypicality consists in.
That concepts are organized into hierarchies isn’t, of course, anything that definitional theories need deny. What primarily distinguishes the new story about concepts from its classical predecessor is the nature of the glue that’ssupposed to hold a feature bundle together. Defining features were
supposed to exhibit severally necessary and jointly sufficient conditions for a thing’s inclusion in a concept’s extension. On the present account, by contrast, whether a feature is in the bundle for a given concept is primarily a question ofhow likely it is that something in the concept’s extension has the property that the feature expresses. Being able to flyisn’t a necessary condition for being a bird (vide ostriches); but it is a property that birds are quite reliably found to have.So, ceteris paribus, +flies belongs to the feature bundle for BIRD. The effect, is to change from a kind of metaphysics inwhich the concept-constitutive inferences are distinguished by their modal properties to a kind of metaphysics in whichthey’re picked out epistemically4
Notice that the thesis that concepts are individuated by their inferential roles (specifically by their inferential relations to their constituents) survives this shift. It’s just that the individuating inferences are now supposed to be statistical.18 19 Afortiori, we’re still working within a cognitivist account of concept possession: to have a concept is, at least inter alia, tobelieve certain things (e.g. in the case of BIRD, that generally birds fly). Notice also that the new story about conceptshas claims to philosophical good repute that its definitional predecessor arguably lacked. Maybe, as Quine says,conceptual entailment isn’t all that much clearer than the psychological and semantic notions that it was traditionallysupposed to reconstruct. But if there’s something philosophically wrong with statistical reliability, everybody is in trouble.
So, then, consider the thesis that concepts are bundles of statistically reliable features, hence that having a concept is knowing which properties the things it applies to reliably exhibit (together, perhaps, with enough of the structure of therelevant conceptual hierarchy to at least determine how basic the concept is).
A major problem with the definition story was the lack of convincing examples; nobody has a bullet-proof definition of, as it might be, ‘cow’ or ‘table’ or ‘irrigation’ or ‘pronoun’ on offer; not linguists, not philosophers,
least of all English-speakers as such. By contrast, the evidence that people know (and agree about) concerning the prototype structure of words and concepts is ubiquitous and robust.50 In fact, you can hardly devise a concept-possession test on which prototype structure fails to have an appreciable effect. Ask a subject to tell you the
first-that comes into his head, and it’s good odds he’ll report the prototype for the category-: cars for
vehicles, red for colours, diamonds for jewels, sparrows for birds, and so on. Ask which vehicle-word a child is likely to learn first, and prototypicality is a better predictor than even very good predictors like the relative frequency of the
word in the adult corpus. Ask an experimental subject to evaluate the truth of ‘a-is a vehicle’ and he’ll be fastest
where a word for the basic level prototype fills the blank. And so forth. Even concepts like ODD NUMBER, which clearly do have definitions, often have prototype structure as well. The number 3 is a ‘better’ odd number than 27 (andit’s a better prime than 2) (see Armstrong, Gleitman, and Gleitman 1983). The discovery of the massive presence ofprototypicality effects in all sorts of mental processes is one of the success stories of cognitive science. I shall simplytake it for granted in what follows; but for a review, see Smith and Medin 1981.
So prototypes are practically everywhere and definitions are practically nowhere.Jean-marc pizano