Abstract

I argue first that some propositions are obligatory without being obligatory for anyone (i.e., they are _impersonally_ obligatory): if each of us has promised to vote and thus has an obligation to vote, then it is obligatory (i.e., morally required) that we all vote, but it is not obligatory _for anyone_ that we all vote (because, for example, what is obligatory for you is that _you _vote, not that we _all_ vote). I argue next that “ought-implies-can” fails for_ impersonal _obligatoriness: if each of us has promised to (and can) finish first in a given race, and thus it is impersonally obligatory that we all finish first (i.e., that we all finish at the same time), it does not follow that anyone (or we) can make it the case that we all finish first (we may be unable to coordinate). I defend instead the following principle: if a proposition is (impersonally) obligatory—or forbidden—at time _t_, then it is _historically contingent _at _t_ (i.e., both the proposition and its negation are logically compatible with the history of the world up to and including _t_).