The Inferential Model of Concepts

It is often claimed that concepts are the building blocks of thoughts. If this claim is true, as I think it is, any adequate theory of cognition will require a theory of concepts. Both philosophers and psychologists have attempted to give such a theory, however, as with most of nature’s building blocks, developing a theory of concepts has not been an easy task. I want to argue that the difficulty is due, in part, to a fundamental error in how one ought to approach a theory of concepts. Most theories of concepts seek to explain the internal structure or the proper parts of concepts. For example, the classical theory of concepts claims that a concept is a set of necessary and sufficient conditions. On the classical theory, each of these conditions is a part of the concept. As another example, the prototype theory claims a concept is a collection of typical features. Again, each feature is a part of the concept. Borrowing a term from Laurence and Margolis (1999) I will say that a theory which emphasizes the internal structure of concepts fits the containment model of concepts. I think that better theories of concepts can be constructed by placing an emphasis on how concepts relate to one another. In particular one should emphasize the inferential relationships between concepts. Borrowing another term for Laurence and Margolis, I will say that a theory which emphasizes the inferential relationships between concepts fits the inferential model of concepts. That a concept’s role in inference should be important part of a theory of concepts is not a novel proposal (e.g., Field, 1977; Block, 1986; Harman, 1987; Pollock, 1989; Peacocke, 1992). However, the proposal has largely been treated as a theory of concepts. My suggestion is that the proposal is not a theory of concepts at all. Rather it is a model in which specific theories of concepts can be constructed. I want to argue that theories constructed under the inferential model are better than theories constructed under the containment model because the inferential model provides tools for constructing a theory of concepts which are not available when constructing theories under the containment model. How a theory makes use of those tools, though, is dependent upon the particular theory of concepts. As a result, my argument will have two parts. First, I will show how to reconstruct two specific theories of concepts, originally constructed under the containment model, to fit the inferential model. This modification results in theories that are both simpler and that have previously unavailable explanatory power. I will then discuss some of the general advantages of adopting the inferential model, using the modified theories as illustrations. The remainder of this paper is comprised of four sections. Section 1 gives a more detailed description of the containment and inferential models. Section 2 discusses the classical theory of concepts. First, I give a detailed account of the classical theory as constructed under the containment model. I then show how to modify the classical theory to fit the inferential model. I conclude the section by discussing the advantages of the modified theory. Section 3 considers the prototype theory of concepts. The structure of Section 3 is otherwise identical to that of Section 2. Finally, Section 4 demonstrates some of the general advantages of the inferential model.