This chapter traces the development of one of the central debates of late 20th-century moral philosophy — the debate between realism and what Rawls called “constructivism.” It argues that realism is a reactive position that arises in response to almost every attempt to give a substantive explanation of morality. It results from the realist's belief that such explanations inevitably reduce moral phenomena to natural phenomena. The chapter traces this belief, and the essence of realism, to a view about the nature of concepts: that it is the function of all concepts to describe reality. Constructivism may be understood as the alternative view that the function of a normative concept is to refer schematically to the solution to a practical problem. A constructivist account of a concept, unlike a traditional analysis, is an attempt to work out the solution to that problem. The chapter explains how the philosophies of Kant and Rawls can be understood on this model.
Keywords: concept, constructivist, describe, Kant, moral, naturalist, practical, problem, Rawls, realist