1. If an agent has free will, then a being identical to that agent with a different causal history has free will.
2. Beings identical to agents with free will with different causal histories are possible.
Therefore, if there are agents with free will, it is possible for there to be agents with free will with different causal histories than them.

This argument seems to suggest that the causal histories of free-willed agents are irrelevant to their having free will.

What should we make of that? We could deny premise 1; this would amount to saying that the causal history of a free-willed agent is an essential feature of such agents, I think. Is this true? I am not sure. I have some inclination to think for example that if I have free will, a being identical to me but produced ex nihilo by a capricious deity would also have free will. That being would have the same subjective states, the same beliefs, desires, hopes, plans, and cares, a materially indistinguishable body, etc.

It's true that some writers make causal histories essential features of agents: for instance Kripke claims that if the actual Queen Elizabeth was born of two parents, it is an essential feature of her that she was born from those two parents and not others; she would not be the person she is without that specific biological organism. So one might claim that it's essential to being the self one actually is that one has a particular causal history of some kind, and then we would deny (1) by saying that two qualitiatively (and physically) indistinguishable persons might nonetheless in one case have and in the other case lack free will just because of their difference in origin. This seems wrong though, both psychologically and in terms of basic modal intuitions. The psychological wrongness comes from the fact that if we have freedom we ought to be able to exercise it through choice, reflection, intelligent action, etc., and qualitatively indistinguishable persons would have the same psychology even if divergent causal histories converged on those persons in the past. Modally speaking, imagine that at the moment of your conception, a quantum mechanical mishap caused your father's sperm to be obliterated, but as a matter of freak chance created a bit of sperm with exactly the same DNA, etc. inside of it, which conceived you. Everything else proceeded in exactly the same way it has and there is now a person qualitatively identical to you with the same DNA as you raised by the same people in the same society etc. except that this person is actually a product of immaculate quantum-mechanical conception. Is there any reason to think that there is a difference between you and this person with respect to free will?

(2) likewise seems hard to deny, unless one thinks everything proceeds by necessity, or that causal histories are essential to agents. A pyramid made of three bricks arrayed in exactly the same way seems to be the same pyramid whether the bottom level went left brick - right brick or right brick - left brick. As long as you wind up with the same structure it's, normally we think anyway, the same pyramid.

Another way one could try to go after the premises is to allow that different causal histories are possible but to restrict them to the right kind of causal histories: if an indeterministic history e.g. is essential to the free-willed agent, than only other indeterministic histories yielding qualitatively indistinguishable beings would yield free-willed beings, or something like that. But why think this? Again, does it really make a difference to a person's psychology or freedom what the inputs going into that person were?

If it does not, and something like this argument goes through, this is good news for the compatibilist. For it's easy to suspect on the basis of the conclusion above that

3. Whether or not a being has free will does not depend on the causal history of that being.

which, to the degree that it has the status of an 'intuition about free will' or whatever label we like to put on philosophical premises that we imagine to be grade A in character, directly contradicts the one I have claimed the traditional libertarian defender of free will wants to assert, and which the problem of distant causation seems to bring up more generally. That is, both

4a. Whether or not a being has free will depends on whether that being is not always (or, necessarily?) ultimately entirely controlled by events external to that agent, and

4b. If an agent has free will, that being must not have behaviors and mental states that are distantly caused/determined/controlled by factors outside that agent.

seem to entail

4. Whether or not a being has free will depends on the causal history of that being.

and (3) and (4) can't both be true without some disambiguation (depends in this sense, does not depend in this other sense, etc.).

Any thoughts?