I find it fascinating that there are people who claim that a belief in absolute, unconditional and unqualified Determinism that would preclude the existence of Free Will is akin to a religious belief that must be rejected without empirical evidence or mathematical proof of its existence, while those same people cling to the fantastical notion that they have Free Will, which is equally unprovable and can be accepted only on faith that it exists. Where there is a competition between beliefs in two equally unprovable and non-falsifiable beliefs, the proponent of neither belief has the burden of proof that the belief that they hold is superior to the belief that they do not hold.
People who advocate Free Will invariably resort to the argument that they make choices and/or decisions all the time, and that they can prove that to be so by being presented with multiple options from which they are free to choose. The fact that such people believe they are engaging in an exercise of Free Will, however, proves nothing, because a belief in something (no matter how real the belief may feel) does not make it so.
Even in a world in which Determinism is not absolute, unconditional and unqualified it may be that humans lack Free Will on account of their physical, genetic, biological, and chemical make-up combined with their history and environment. As such, it is logically possible to posit a world that is not perfectly deterministic and in which humans lack Free Will. It is not, however, logically possible to posit a world that is perfectly deterministic and in which humans have Free Will -- unless, of course, Free Will is defined as the exercise of a response to antecedent activity that could not be other than it is (even before the exercise occurs).
Most compatibilists accept the proposition that a person could not have acted differently than they did act after the act has occurred. But that also means that the person could not act differently than they are about to act before the act occurs -- otherwise, it would not be true to say after the act occurs that the act could not have occurred in any different way. Rather, it would simply be the case that the act, which could have occurred in any one of multiple ways, occurred in one particular way i.e., the way it occurred) and cannot be changed after the fact. So long as one accepts the proposition that all historical activity has occurred in the only way it could have occurred (as opposed to simply the only way it did occur), then all such activity was pre-determined to occur by antecedent activity before it actually occurred. That precludes the existence of true Free Will, and leaves only the possibility of an illusory Free Will in which a person does not know how they will act before doing so, but also is subject to the compulsion of the universe to act in only one manner.
As I have said before, I am not advocating that the universe is, in fact, perfectly deterministic. I am simply drawing a logical conclusion from what it means for the universe to be so.
Conversely, I would argue that a universe in which true Free Will does exist logically precludes that universe from being perfectly deterministic -- at all levels, and not simply at the quantum level. If the universe is not perfectly deterministic, then the universe must be entirely probabilistic, because any unforeseen activity in the seemingly natural course of the universe is capable of producing a ripple effect far beyond its probable consequences. In a probabilistic universe, anything is possible (even if not probable) except, perhaps, for the possibility of something being impossible. In a probabilistic universe, there can be no certainty about any future activity of any aspect of the universe, because there is always the possibility of one or more improbable actions occurring that will materially disrupt the seemingly natural operation of the universe.
I am confident that there will be folks on this board who will reject this post out of hand, based upon one or more non-logical arguments that will be based on emotional attachment to Free Will and/or a refusal to accept the premises of the post. Invariably, some of those folks will resort to ad hominin attacks, which say far more about the person makin the attack than about the target of the attack. More often than not, the rejection of this post will turn on claimed scientific or mathematical proof that is asserted to exist, but will not be shown in sufficient detail to support the claim -- because no such proof truly exists outside the minds of people who claim to assert the existence of such proof. For all of these reasons, to the extent I am able to do so, I will not be replying to comments that fail to accept the premises of the philosophical discourse this post is intended to engender, and argue instead based on changing the premises. If the logic of the arguments flowing from the premises is flawed, I would be pleased to learn about it. If, however, someone simply does not like the logical conclusions that flow from the stated premises of the argument, there is no point in engaging in discourse.
Let the games begin -- again, no replies to irrational assertions will be forthcoming
