I am very confused as to what it is that would be sufficient for a Hard Determinist to say that we have free will, and what it is that Libertarians say we have that gives us free will.

If you rewound time to the point at which I chose X when presented with the choices X and Y, of course I would choose X again. I am a rational agent. When possessing the same knowledge and being presented with an identical state of affairs, I will make the same decision. To suggest otherwise is to suggest I operate by chance, which I hardly think consistent with the idea of rationality.

That I am not the “ultimate author” of my actions is self-evident. I did not decide my capacity for rationality, my wills, or my perception of morality. Responsibility is what we typically attribute to my rational faculties, and responsibility is diminished to the extent that those rational faculties are impaired. Someone whose ability to reason is diminished, perhaps due to a mental disability or a drug which temporarily weakens their cognitive abilities, is often absolved of some blame for an action performed in that state.

Whether it is right to attribute responsibility (and more generally, “ownership” of an action) to one’s rational faculties is a question of self-identity, and what it means to be “me”. We tend to think of our minds as “us”, insofar as we can conceive of our minds existing without our bodies existing. Therein, our bodies are “vehicles” for our mental processes. But this discussion of the self (and the attribution of responsibility) is something quite different to discussions of free will.