Practical reason: rationality or normativity but not both

The term ‘practical reason’ has two quite different meanings. They arise from the ambiguity of the noun ‘reason.’ In one of its meanings, practical reason can be identified with rationality and in the other with normativity. But the two meanings are often fused in philosophy, and indeed the distinction between rationality and normativity is often obscured. There are philosophical theories that identify the two. This chapter aims to hold apart the two meanings of ‘practical reason.’ It starts by analyzing the rational meaning and the normative meaning in sections 2 and 3, respectively. Section 4 gives a simple reason for thinking that rationality and normativity must be distinct: one is a mental property, and the other is not. Your degree of rationality depends only the properties of your mind, whereas often you ought normatively to act on the world outside your mind. Section 5 examines and rejects two possible responses. One denies that rationality is a mental property; the other asserts that normativity is a mental property. Section 6 describes a different argument in a Kantian spirit. A special, reified concept of Rationality might possibly be united with normativity, but it is far from our ordinary concept of rationality. Section 7 summarizes the chapter’s argument and draws the conclusion that the two meanings of ‘practical reason’ cannot be successfully unified. This book therefore covers two distinct topics.