I've had some interesting correspondence about the concept of libertarian free will since I discussed this in the context of Lee M. Silver's Challenging Nature. I maintain that the idea has never been developed in a form that is intellectually coherent, and that there is no real prospect that it ever will be.
That raises two related groups of issues. First, if I am correct is it a tragedy? Putting it another way, how deeply are we committed to this idea as part of our ordinary concept of ourselves as agents? What have we lost if the idea needs to be jettisoned? In my view, it is not a tragedy at all, since compatibilist free will is the only kind of free will worth having, but I expect a lot of people will disagree with me. Since I was a child, I've never found the idea of libertarian free will even slightly plausible, but I am probably in the minority on that. Second, have we fully thought through the implications, not only for theology and philosophy of religion but also for many of our social practices, such as those of reward and punishment? It is at least possible that some of our important practices make metaphysical assumptions that cannot be supported by reason. If so, what then?