We like to think that we are sometimes morally responsible for some of the things we have done. It seems natural to suppose that if a person is morally responsible for something he has done, then he could have done otherwise. But there is a puzzle here. Precisely what do we mean when we say of a person who acted in a certain way that “he could have done otherwise”? Chisholm takes this as a fundamental question in the metaphysics of action. It seems to be his way of conceiving of the so-called “free will problem”. He discussed this topic in “Freedom and Action” (1966), “He Could Have Done Otherwise” (1967a) and then again in [P&amp;O] as well as in quite a few other papers. It would be very difficult to describe in detail all the twists and turns of Chisholm’s constantly evolving views on this topic. Instead, we will focus on some of the more persistent and characteristically Chisholmian points.