Rea has an interesting paper arguing that if one assumes bivalence, then presentism is incompatible with free will. I think there are problems in his argument, but I was also thinking that there might be a variant argument to similar effect.
Start with this. Sally intentionally started a forest fire F, but she ceased to exist before the fire started. (E.g., she set fire to a pool of gasoline, intending the fire to spread to the forest, but ceased to exist before the fire spread to the forest.) The forest fire, then, is plainly something that Sally had a choice about, something that Sally is (or was? — the grammar of English is unclear on this point) responsible for.
A1. If x had a choice about the occurrence of E, then E depends on x.
A2. If E never depended, does not depend and will never depend on x, then x never had a choice about the occurrence of E.
A3. Necessarily, if E depends on x, then x exists.
A4. If E depended, depends or will depend on x, then there is a t such that E depended, depends or will depend on x at t.
A5. If E depended, depends or will depend on x at t, then it was, is or will be true at t that E depends on x.
A6. If was, is or will be true at t that E and x exist, then E and x existed, exist or will exist at t. (Presentism)
A7. Necessarily, if E depends on x, then E and x exist.
A8. Suppose for a reductio that Sally had a choice about the occurrence of F.
A9. Therefore, F depended, depends or will depend on Sally. (A2, A8)
A10. Therefore, there is a t at which F depended, depends or will depend on Sally. (A4, A9)
A11. Therefore, there is a t at which it was, is or will be true that F depends on Sally. (A5, A10)
A12. Therefore, there is a t at which it was, is or will be true that F and Sally exist. (A7, A11)
A13. Therefore, there is a t at which F and Sally existed, exist or will exist. (A6, A12)
A14. There is no t at which F and Sally existed, exist or will exist. (Sally ceased to exist before F started.) This contradicts A13!
Now, let t0 be the time at which Sally is setting fire to the gasoline. Then, at t0, the forest fire does not exist. But, perhaps, the state of affairs F* of a forest fire being about to happen exists. And F* depends on Sally. This seems to be the answer that those presentists who believe that truth supervenes on being will give.
It’s worth noting that this answer will fail if one accepts open future views, because at t0, F* does not yet exist, since it is not yet settled whether a forest fire will occur. After all, God might miraculously intervene, or weird quantum stuff might happen and the heat might all transmute into a dance of trees.
But suppose we reject open future views. Still, what does this answer come to? It comes to this: Sally had a choice about F*. Yes–but it is F* that we attribute to her, because F* does not exist. What exists now is F, and this Sally had no choice about, because F, unlike F*, never depended on Sally, since never was it the case that both F and Sally exist.
Here is a simpler variant.
B1. Being responsible for F is a property.
B2. One only has properties if one exists.
B3. One only exists if one exists presently. (Presentism)
B4. Sally does not exist presently.
B5. Therefore, Sally does not exist.
B6. Therefore, Sally does not have properties.
B7. Therefore, Sally is not responsible for F.
Now, an obvious retort is that Sally is not responsible for F, but she was was responsible for F. But this fails: for at any time at which F exists, Sally does not, and so Sally never was responsible for F, assuming B1-B3. All we can say is that Sally was responsible for F*. But F* is not such a big deal. It is F we’re worried about. (A forest fire’s being about to happen is only of interest because it is followed by a forest fire.)
Of course, one might say that our grammar misleads. “Sally is (or was) responsible for the forest fire” should be read as short for: “Sally was responsible for its being the case that a forest fire is about to happen.” Open futurists can’t say that, but other presentists can. Still, there is a cost for all closed futurist presentists. For they all leave it a mystery how what F has to do with Sally, given that Sally was only responsible, “in the proper sense of the word”, for F*. Is it a transitivity, maybe? Sally was responsible for F*, and F* caused F? But how could F* cause F, given that if A causes B, then A exists and B exists, whereas at no time did both F* and F exist, and hence never did both F* and F exist (assuming Presentism).