Acting and believing on the basis of reasons

This paper provides an opinionated guide to discussions of acting and believing on the basis of reasons. I aim to bring closer together largely separate literatures in practical reason and in epistemology. I focus on three questions. First, is basing causing? Causal theories of basing remain popular despite the notorious Problem of Deviant Causal Chains. Causal theorists in both the epistemic and practical domains have begun to appeal to dispositions to try and solve the problem. Second, how unified are acting and believing on the basis of reasons? I consider an important challenge to their unity due to Setiya. I sketch a response, which posits unity of causal structure across acting and believing on the basis of reasons. Third, how does acting or believing on the basis of a good reason relate to acting or believing on the basis of a reason simpliciter? I generalize a recent argument of Lord and Sylvan's to include acting as well as believing. The conclusion is that, for both believing and acting, phi ing on the basis of a good reason does not amount to phi ing on the basis of a reason that just so happens to be good.