INTRODUCTION

Like adults, children use categories as a basis for inductive inference. Having learned that some property is true of some individual (e.g., “My dog, Magic, likes marshmallows”), a child might assume both that other members of the same category (dogs) share this property and that members of other, similar categories (e.g., cats) might also share this property. In short, inductive inference may be guided by and reflect categorical relationships, hence the term “category-based induction” or CBI. Cognitive and developmental researchers have used a category-based induction paradigm not only to study the use of categories in reasoning, but also to draw inferences from patterns of reasoning about the nature of conceptual structures themselves (Atran et al., 2001; Carey, 1985; Gelman & Markman, 1986; Gutheil, Bloom, Valderrama, & Freedman, 2004; Gutheil, Vera, & Keil, 1998; Hatano & Inagaki, 1994; Inagaki, 2002; Johnson & Carey, 1998; Medin & Smith, 1981; Ross, Medin, Coley, & Atran, 2003; Waxman, Lynch, Casey, & Baer, 1997).

One of the most influential examples of the use of inductive projections to draw inferences about conceptual organization comes from research in the domain of folk biology involving categories of living things, including humans, nonhuman animals, and plants. Developmental evidence has revealed, in particular, certain systematic asymmetries in inductive strength among these categories. For example, researchers have found that children are more willing to project properties from humans to dogs than from dogs to humans.