The problem of free will is always confusing, as linguistic and empirical considerations get boiled in the same pot.
The term “free will” existed before any conception of the universe as deterministic existed, just as the word “water” existed before we understood that it’s made of hydrogen and oxygen.
Hence, the term “free will,” at least in theory, is pointing to something in our experience that we can learn more about, just as we could learn more about water.
The question really becomes, What is the term “free will” pointing toward? I’m not asking for a definition; I’m asking whether there are any phenomena that we associate with this term.
Obviously, they would have to be psychological phenomena, things that pertain to introspection and consciousness. I think when you really get down to it, “free will” refers to the fact that our biological and mental lives require us to choose between alternatives. As you know, you can’t set your brain on autopilot. You can’t just tune out for a week while your body studies for the
SATs, goes to the test site, and wakes “you” up for an enjoyable weekend. No, it’s always you, whatever that “you” might turn out to be.
So, we’re compelled to think, to make choices. Likewise, we are able to think and make choices, even when not compelled; or at least there is no pain or distaste associated with the choice. I can choose strawberry or chocolate ice cream.
Hence, whatever consciousness or personhood is in your worldview, you have to think and make choices. You are forced to be conscious.
Now let’s advance the argument one level. Even if we decide that consciouness is 100% deterministic, that fact is irrelevent to the question of whether we are free. Why? Because, again, free/unfree is a concept originally applied to the phenomena of consciousness by that consciousness, so the concept can only be superficially voided by information external to that system.
In other words, if you say “But it’s not really me that is deciding if the universe is deterministic,” that’s wrong, since the terms “me” and “deciding” were originally applied to the decision-making system (consciousness), regardless of what we could further learn about that system.
As a counterexample, suppose I believe in a soul. I taste some ice cream and say, “I really feel this tastes sweet.” But later on I determine that the soul doesn’t exist. Does it make sense at that point to say, “I guess this ice cream doesn’t really taste sweet to me, since there is no soul in me really to taste it.” Nonsense, of course, since “sweet” originally applied to an introspective phenomenon.