Did 'might' make right? Epistemic modals in practical reasoning

Many philosophers have recently adopted a nonfactualist semantics for epistemic modals. In this paper, I pose a challenge for nonfactualism. I begin by noting that we often cite previously uttered epistemic-modal sentences as justifications for particular actions. Moreover, as I show, any utterance of an epistemic-modal sentence can, in principle, be later cited as justification for some action that was taken in light of it, even if the prejacent has since been revealed to be false. I then show that to justify action in this manner, utterances of epistemic-modal sentences must be construed as asserting propositions about what is compatible with the agent’s informational state at the time of assertion. This is incompatible with standard forms of nonfactualism about epistemic modals.