Here, I argue that knowledge-level justification for p suffices to make it rationally permissible to treat p as a reason for action. I will arrive at this conclusion indirectly, by first defending the sufficiency direction of the knowledge norm for practical reasoning (KRS) in sections 4.1–4.4 against popular counterexamples. In section 4.5, I consider why our intuitions about the counterexamples are misleading. In section 4.6, by running the subtraction argument presented in Chapter 2, I argue that knowledge-level justification for believing p suffices in all contexts for rational permissibility and I point out how this view still vindicates part of the knowledge-first project.

In this chapter, I argue for a contextualist approach to epistemic norms for practical reasoning, according to which the degree of justification required for it to be permissible to treat p as a reason for action varies with context. In section 3.1, I introduce how these proposals are motivated and three questions that will shape the following discussion. In sections 3.2 to 3.4, I discuss the proposals of Brown, Gerken, and Locke in turn. The most pressing issue for current contextualist accounts is what I call the incompleteness problem, which is how context determines what degree of justification a context calls for. In section 3.5, I develop a solution to the incompleteness problem that involves a comparison of two opposing costs, the costs of error and the costs of further inquiry. Finally, I point out a context-invariant principle that will become significant in Chapter 5.