Human Nature and the Limits (If Any) of Political Philosophy

It is often supposed that a person is not required to do anything they cannot do. “Ought” implies “can,” as this is often put. Let’s accept that for the sake of argument. Still, it is not obvious that if I can’t muster the will to do something, then I can’t do it. An inability to will an action might not entail an inability to do the action, in which case the action might yet be required. I will discuss this question shortly. In any case, here is a related but different idea: even if it is not impossible to do whatever it is impossible to muster the will to do, perhaps it is still implausible to think one could be required to do what one could not muster the will to do. Perhaps we should accept that “ought” implies “can will.” If so, and if there are characteristic things that humans cannot muster the will to do, then human nature (in the sense of the limits of human motivational capacities) would stand as a prior set of facts that constrain what political philosophy can soundly prescribe or morally require. My thesis, simply stated, is that this is not so. If there are facts of human nature of this general kind, consisting in limits to what humans will be able to muster the will to do, they are not, simply as facts, constraints on what can soundly be prescribed or morally required. The reason is that agents’ abilities and inabilities to muster their will are subject to moral evaluation in their own right. Some such inabilities are