We have two definitions of free will. One is meaningful and relevant. The other is meaningless and irrelevant. The real question is, “Why would anyone choose the meaningless and irrelevant definition?”
In operation, “free will” refers to a person deciding for themselves what they “will” do, “free” of coercion or other undue influence.
This is meaningful because it distinguishes between a deliberate act, versus an act that someone was forced to commit against their will. In matters of moral and legal responsibility, we hold the person accountable if they acted deliberately, but if they were coerced, then we hold accountable the guy who held a gun to their head.
And it is relevant because coercion or undue influence may be present or absent. Either you made the choice or someone else forced the choice upon you.
Okay, so what about the other definition of “free will” the one where it is defined as “freedom from causal necessity/inevitability”? Well, if we presume perfectly reliable cause and effect, then every event that ever happens is always causally necessary or causally inevitable. And, of course, this would include all the events in our mind as well.
But is that meaningful? Actually, no. Because it turns out that what we will inevitably do is exactly the same as what we would have done anyway. It is just us, being us, doing what we do, and choosing what we choose. And that is not a meaningful constraint.
Yet perhaps it is still relevant? Afraid not. Reliable cause and effect is not something that can be either present or absent. It is a background fact of all existence. It is not something which we can in any sense be “free of”.
So, what are the grounds for replacing a meaningful, relevant operational definition of free will, with a meaningless, irrelevant one?
It appears that many philosophers and scientists, people who really should know better, have somehow managed to play a big joke on themselves. But I think it has ceased to be funny.