Let L be the laws of nature. Suppose:
- Everything in the causal history of the coming into existence of an entity is essential to the entity—it is impossible that that very entity exist without it. (Essentiality of origins)
- The complete causal history H of the coming into existence of Bob together with L entails every action of Bob's. (Determinism-plus)
- Bob cannot exist unless L is true. (Strong nomic boundededness)
- If it is metaphysically impossible for Bob ever to do otherwise, Bob is not free.
- Bob is not free.
Essentiality of origins is very controversial, but I think there are very good theoretical reasons to posit it. It yields, for instance, a very neat account of transworld identity.
Determinism-plus isn't just determinism. For suppose we live in an infinite deterministic universe and relativity theory holds. Then the backwards light cone of every action of yours is wider than the backwards light cone of your initial coming into existence, and there may be causal influences on your actions that did not influence your coming into existence. In such a setting, determinism-plus is false. On the other hand, determinism-plus is going to be true in a more Newtonian universe, where everything affects everything else instantaneously (say, via gravity), and so the causal history of your coming into existence contains all of the universe's state prior to your coming into existence. Also, in a some small finite relativistic universes, we might have determinism-plus.
Furthermore, determinism-plus's understanding of laws of nature rules out miracles. That's a serious problem. It may render determinism-plus incompatible with theism. Still someone, especially a non-theist, might think:
- If freedom is compatible with determinism, freedom is compatible with determinism-plus.
And I know there are compatibilists who are willing to deny (4).
This is a pretty weak argument. Still, it's worth thinking about. For the problems with the premises don't seem to be such as to be deeply relevant to whether there is free will. Maybe there is some way of building a better argument out of these options. I leave that for the reader.