Preliminaries

Categories, categorization, and the organization of information are crucial topics throughout the broad realm of cognitive studies, not merely in philosophy but in both theoretical and empirical work in linguistics, psychology, and the brain sciences. Each of these disciplines offers intriguing findings regarding the ways we categorize—findings of importance for the understanding of human knowledge.

The central philosophical point that categories are crucial for cognition, in general, is fully recognized in the empirical work of other disciplines. As the linguist George Lakoff emphasizes,

A point that is clear philosophically, and essentially a priori, is that categorization and discrimination are linked. To recognize things as belonging to different categories is to be able to discriminate, at least conceptually, between items in those different categories. The “at least conceptually” allows us to say that we can discriminate between prime numbers greater than a googol and non-primes greater than a googol, though actually being able to name any of the former may be beyond our abilities. With that proviso, indeed, to recognize things as belonging to different categories is to discriminate between them.

This in no way forces us to say that all discrimination entails categorization: that if we recognize that this thing is different than that, it must be because we have assigned the two things to different categories. Categories are kinds, with the kinship of kinds determined by the pragmatic context of our purposes. Two things x and y will always belong to different sets or different arbitrary collections: we need to merely think of (1) the set to which the coins in my pocket and x belong as members and (2) the set to which the coins in my pocket and y belong as members.