The revival of interest in domains of cognition, especially in the contexts of cross-cultural and developmental studies, is a welcome new awareness of how different sorts of concepts and belief systems might become tailored to particular kinds of lawful regularities in our physical and social worlds. To make much progress, however, this new emphasis requires more precise distinctions between types of domains and better descriptions of the ways in which each type might vary across development and cultures. We can talk about domains as rarefied as a cardiologist's knowledge of arrhythmia to those as commonplace as everyday folk psychology. Domains can vary from the highly concrete causally rich relations in a naive mechanics of physical objects to the highly abstract noncausal relations of mathematics or natural language syntax. Lumping together all of these different sorts of domains so as to have similar effects on cognitive development is likely to be misleading and uninformative. In this chapter, I consider some distinctions and their implications for questions concerning the origins of concepts.

The focus of this chapter is on the emergence of biological thought. Concepts of living things may offer an especially clear illustration of how domains might be involved in the origins of more specific concepts, and conversely of how specific concepts become intertwined within larger belief systems. In addition, views of concept structure and use have increasingly invoked the special importance of those belief systems known as theories.

Introduction

A new emphasis has emerged in the literature on concepts and concept acquisition. There is now a strong focus on the role of theories and other explanatory belief systems in structuring concepts and conceptual change. A series of recent studies on adult concepts (e.g., Medin & Wattenmaker, 1987; Murphy and Medin, 1985; Rips, 1989) and a rediscovery of older work, such as Asch (1946), Luchins (1957), and Chapman and Chapman (1969), as well as developmental analyses (e.g., Carey, 1985; Keil, 1986, 1989; Wellman & Gelman, 1988), reveal the vital importance of theorylike beliefs in understanding concept structure and development. At roughly the same time, and for subtly related reasons, there has been a resurgence of interest in domain specificity of knowledge in cognitive development, with the consequence that researchers are now wondering whether the development of knowledge in different theoretical domains might influence concepts in ways that are unique to each domain. This chapter assesses how these two trends link up to help us understand the acquisition of word meaning.

Although the mapping between concept structure and semantic structure is certainly not one to one, as has been clearly illustrated by Clark (1983), neither are the relations random. I will argue that higher structural relations within and across concepts, as well as patterns of conceptual change, can have major and systematic influences on word meanings themselves. In this chapter I explore four aspects of concepts and conceptual change that may be particularly relevant to our understanding of semantic development: (a) interdomain differences, (b) causal beliefs versus atheoretical tabulations, (c) differentiation versus sharpening, and (d) the effects of a changing conceptual base on lexical induction.