A quick Thomistic argument for alternate possibilities

1. I freely choose between A and B only if I am deciding in the light of a non-dominated reason for A and a non-dominated reason for B.
2. A non-dominated reason for C is a causal power for deciding in favor of C.
3. If x has a causal power for φing, then x can φ.
4. So, if I freely choose between A and B, then I can decide in favor of A and I can decide in favor of B.

Acting otherwise and choosing otherwise

The traditional Humean compatibilist position, prior to Frankfurt's examples, is that a deterministic agent who is free could still have acted otherwise because

1. had she wanted to, she would have acted otherwise.

But the question relevant for determination of responsibility isn't whether one could have acted otherwise (uncontroversial Frankfurt cases, where Black acts only after the choice has been made, show that), but whether one could have chosen otherwise.

I wonder if a similar conditional-type of story can be told about the ability to choose otherwise? The obvious analogue to (1) is to say that

2. had she wanted to, she would have chosen otherwise.

But actually this condition is often false despite the agent being free. For it often, perhaps even always, happens in the situation of a free choice that the agent both wants to choose A and wants to choose B, but because she cannot go for both, she must choose between them. Suppose the agent chooses A. It is surely false that had she wanted to, she would have chosen B. For she did want to choose B, and did not—what better refutation is there of the subjunctive conditional than that the antecedent is true but the consequent is false?

But presumably in this case the agent didn't on balance want to choose B. So perhaps our compatibilist-friendly alternate possibilities condition is:

3. had she on balance wanted to, she would have chosen otherwise.

That may be true, but it is obviously a very weak condition. Perhaps even a trivial one. Indeed, we might reasonably say that what is constitutive of the agent's on balance wanting to choose A is precisely that she is such that given the choice she will choose A. If so, then (3) is trivially true in every case. And even if it's not trivially true in every case, it's going to be true in too many cases of freedom-canceling brainwashing to capture the alternate possibilities intuition.

It may be wiser, then, for the compatibilist to simply retreat from affirming any kind of alternate possibilities condition on freedom. But there is a cost to that.

(I am omitting consideration of the usual finkish objections (of which Frankfurt cases are one of the earliest examples) to conditional analyses. Maybe there is some way around those.)