Jonathan Caleb Kendrick

The Lewis–Kratzer restrictor theory of conditionals struggles to account for a key difference between epistemic and deontic conditionals: while the epistemic conditional “if $$\varphi $$, must $$\varphi $$ ” is trivially true, the deontic conditional “if $$\varphi $$, ought $$\varphi $$ ” is not trivially true. I propose a simple solution to this problem: deontic and epistemic modals are sensitive to different kinds of reasons. Deontic modals are sensitive to reasons for action, while epistemic modals are sensitive to reasons for belief. The initial contrast arises because, while the fact that $$\varphi $$ is always a reason for believing $$\varphi $$, the fact that $$\varphi $$ is not always a reason for doing $$\varphi $$. In this paper, I make this intuition precise by drawing on the default premise semantics proposed by Cariani (2024, 2025) which enriches Kratzer’s (1981a, 1986, 2012) premise semantics for modals and conditionalsis intuitively true. Given reasonabl with default rules from non-monotonic logic (Reiter, 1980; Horty, 2007b, 2012).