A Rough Account of Substantive Rationality

This chapter gives a rough account of substantive rationality, the kind of rationality that contrasts with the book’s main topic, structural rationality. On this account, which mirrors some recently popular accounts in the literature, substantive rationality consists in responding to evidence-relative, right-kind reasons. It also argues against further restrictions on the kinds of reasons relevant to structural rationality—such as a “practical condition” and a condition excluding moral reasons—and introduces the distinction between ex ante and ex post substantive rationality. Finally, it explores accounts of structural rationality that closely mirror the offered account of substantive rationality by understanding the former as responsiveness to “subjective” or belief-relative reasons and argues that these accounts fail.