Abstract

Fish gotta swim and birds gotta fly . Robins eat worms, dogs chase cats, roses love sunshine . These kinds of relations are as much a part of our understanding of the world as are the direct properties of the entities themselves . Relational knowledge is a prominent feature of human categories-indeed, of human cognition in general . Nowhere is this clearer than in our ability to learn relational categories like gift, weapon, predator, or central force system. By relational categories, I mean categories whose meanings consist either of (a) relations with other entities, as in predator or gift, or (b) internal relations among a set of components, as in robbery or central force system . My purpose here is, first, to discuss relational categories and how they are learned, and second, to discuss how children learn relational information about object categories . Relational categories contrast with object categories' (e.g., tiger or cow), whose members share intrinsic features, often including perceptual commonalities. Of course, object categories typically 'contain not only property information but also relational information . For example, that tigers hunt and eat animals is part of our concept of a tiger, along with intrinsic attributes such as their stripes . I return to the role of relational information in ordinary object categories later . For now, I make a strong contrast between object categories and relational categories, to better reveal the dimensions of difference .