Oh no not another free will thread.

[Edwardo Piet]

There's two conceptions of free will:

1: Compatabilist free will.
2. Incompatabilist free will.

Compatabilist free will stems from the philosophical view compatabilism, which is the view that free will can be compatible with determinism. In philosophy, determinism is the view that there is at any given moment exactly one physically possible future and all events can be traced back to prior causes, stretching back to the big bang and further if needed, to the first cause.

This means that in determinism, any action you take is determined by prior causes... so you couldn't have possibility done otherwise.

Now, whether you believe determinism is true or not, compatabilist free will is so loosely defined that it's possible even in such a universe. Meaning, even if you can't do anything other than you do... free will is still possible. How so? Because on the compatabilist view, all 'free will' means is to not be psychotic, not be drugged, to be a legal adult, to not be hypnotized, to not be coerced. It's just the free will in the sense that is meant in the legal system, the legal sense of free will. Or what is meant when asked the question "Are you signing this contract of your own free will?". It means, are you a responsible adult capable of making such decisions, are you mentally mature, are you being coerced?

If that's all free will is, then of course it exists. There's a big difference between your brain leading you to behaviors when you're fully sober and sane, and your brain leading you to behaviors when you're say, drunk, or psychotic, or you have a gun to your head. Obviously, your 'free will' is violated when you aren't in a sober state or you're being threatened by violence, or you're psychotic, etc.

The problem is most people believe in more than that. Most people do believe that they can do otherwise in exactly the same situation. Most people believe determinism is false, or they simply don't think about it. Most people may think that quantum mechanics supports indeterminism, because quantum events can't be unpredictable.