For a half - century, I have been developing a view of free will that is incompatible with determinism and, in the process, attempting to answer the Intelligibility Question about such a free will: Can one make sense of an incompatibilist or libertarian free will without reducing it to mere chance, or mystery, and can such a free will be reconciled with modern views of the cosmos and human beings? In this paper, I discuss recent refinements to my earlier writings (...) on such a view, refinements developed in recent years in response to the large critical literature on my views in the past several decades. My view has usually been designated an event-causal view of libertarian free will and distinguished from non-causal and agent-causal libertarian views. But I was never happy with this designation of my view as “event-causal” and did not use it myself in earlier writings. In this paper, I explain why I now reject it altogether. I have come to believe that to avoid numerous misunderstandings in current debates about free will, we must distinguish four different kinds of libertarian theories, not merely three: in addition to non-causal, agent-causal, and event-causal theories, we need to add a fourth kind, which might be called an agent-causal/event-causal theory. My view has always been of this fourth kind. It represents what I call in the title of this paper the “fourth way forward” for making sense of an incompatibilist free will. (shrink)