Complicated questions tend to need complicated answers. How about this: Assuming the world is deterministic, can there be free will?
No, yes, no, yes, no, yes, no, and yes. As follows:
If events in the world are fully determined, we cannot change what happens, hence we cannot make choices.
We think we think we must have a choice in the sense that we could have made a different choice in the exact same circumstances, but implicitly that’s not what we really want. We want to be able to do what we want. If our desires are the thing that determines what we choose, then the choice is free. This idea is called voluntarism. It works even in cases where we want to resist some particular desire — as we do want to resist it, we just want the desire to resist be the one to get followed.
That doesn’t work because we can show examples where we act out of a desire but not freely. If someone’s making you do something at gunpoint, you’ll want to do what they’re telling you so as not to get shot, but that’s not a free choice.
It’s true voluntarism needs to be amended by adding stipulations such as that someone else forcing you to do things is never freedom. This doesn’t contradict determinism, though, just an oversimplified view of voluntarism.
Well, regardless of all that, what we mean by free choice does involve the possibility of doing otherwise in a strong sense. Not just that if you wanted to do otherwise, you’d do otherwise. Not every person has the same intuitions, but this seems to be a very common requirement. It can also be shown people implicitly want to do what they want to, not undetermined things. This shows that the very concept of free will that we have is contradictory; it requires both determinism and indeterminism. As such, we certainly can’t have free will.
Yes, that intuitive concept of free will is contradictory. However, the discussion under voluntarism above shows that we don’t actually need the part about it being possible to do otherwise under the exact same circumstances — the one that contradicts determinism. It may be part of our intuitive concept, but we can use a concept that leaves it out, and we’ll lose nothing but the contradiction. What’s actually valuable about free will, and what we should wish for, and what we usually implicitly assume anyway, is a version of voluntarism where we are able to act on our best desires. In other words, we can change an existing concept if that’s rational to do.
All right then, we’ve solved the conceptual problem. How about we now look at the actual world? People having free will is threatened by something quite else than the general possibility of determinism. People constantly act irrationally and out of reasons they don’t even see at the time — not the best reasons. They are determined by the wrong reasons. Humans have the capacity in theory to rationally deliberate and act to their best interests, but their brains and bodies are also built with all kinds of other systems that often influence them instead, leaving the thinking part to rationalise or bemoan irrational acts.
True — but note the part that we do have the capacity to be free. To be as rational as possible in the sense that it makes us free is what we should aim for. It’s also what we should ask of ourselves and others. If we conceptualise ourselves and others as not free, we and they are less likely to be and become more free. We can become more free, and we should do it to make the world a better place, so we should stress the capacity to become so, not the grim fact of how little people may be free already.
The lesson: A lot of questions can’t just be answered “yes” or “no”. In addition, understanding how “opposite” answers can be true at the same time is deep understanding. In the above example, there’s a kind of succession of increasing understanding, with every answers mostly involving understanding of the answers above it but also going beyond them. Of course, these are really brief summaries, and don’t necessarily give out the understanding that leads to them. The matter would need to be discussed at more length if it were more than an example.