I would very much like it to be the case that I am free. But what (I've been wondering) is it that I want?
I don't just want to have choices-- to be able to choose A or B. Sure, it would be nice if I could have chosen chocolate, though I chose strawberry, but really, so what? I'm not too distressed by the idea that I'm a strawberry-choosing marionette.
The best way I can explain what I do want is by analogy with divine agency. We have this idea of a deity who has thoughts about what he wants to happen. He sees that the current course of events will lead to outcome A, but he wants B to occur instead. He doesn't intervene as a result of the past; it's all about B--he wants it, so he intervenes. And he's effective. His intervention changes the future so that B will occur instead of A.
It doesn't seem like this sort of agency and impact is too much for a person to want. The way things are going, let's pretend, it appears I will not wake up in time to catch a plane tomorrow morning. I want to catch my plane, not miss my plane. So I try to alter the future--I set my alarm. I do that because I want to catch my plane, period; not because of the past. Before I intervened, I was heading for missing my plane, and now I'm heading for catching my plane. Thus, in this portrait, I have the power to alter the future on the basis of my own reasons.
All that seems eminently desirable--it makes sense to want to make a difference to the future, and to want your own reasons to be in charge. That's what I want, but can I have it?
There are two sticking points. Can it really be true that I set my alarm for the sake of catching my plane, period? If determinism is true, then the past made it inevitable that certain brain events would occur, and they would cause me to set my alarm. You could tell the whole story about what led to the alarm setting, without even mentioning the plane. That's not what I want.
The other sticking point has to do with the description of the intervention (setting my alarm) as diverting the future from one trajectory to a different one. If determinism is true, there was always just one trajectory. My thought about not missing my plane was on that single trajectory, and so was setting my alarm.
One strategy for defusing angst about free will is to say there's nothing really desirable about having it, but it seems obvious that it is desirable. Having free will is getting to have things turn out differently in the future, owing entirely to your reasons. What's not to like?!