I saw an argument a while ago:

1. Everything in nature is either determined or random
2. Free will is neither determined nor random
C. Free will does not exist.

This seems like a good argument to me. It seems to me that neither a deterministic algorithm nor a random number generator have free will. If we are entirely composed of such elements, then we cannot have free will, because all of our choices could be decomposed into elements that are not free. Therefore, I concluded a while ago that belief in free will is the same as belief in the supernatural.

Free will in principle seems to be outside the scope of mathematical/scientific description, because the laws of a system describe how a system must be, but the "free" in "free will" means that we are not forced or predetermined to do anything, and thus free will could not be described by any kind of law.

My father said once, however, that he thinks that the randomness of quantum mechanics might somehow contribute to free will. I didn't like the idea at first because of the above argument, but after thinking it over, it does sort of make sense. I will discuss some other ideas relating to free will first, however.

Even if our choices were fully determined, in practice, the processes leading to our choices are extremely complex, so that nobody would ever be able to predict with certainty ahead of time what a person might do.

Also, I've heard from computer programmers that it is generally impossible to know in advance what the result of a computation will be. The fastest way to find the result of a computation is to just do the computation. Therefore, whatever computations are going on in our heads, it is generally impossible for anyone (including ourselves) to know what we will settle on before we have settled on something. This is another point that explains why we have the experience of free will, even if it might not technically exist.



Now, for the problem of a system that has both deterministic and random elements. I imagine that the human mind is mostly deterministic, but that the exact manner in which we perceive events may have some randomness in it due to quantum effects that might take place at the level of individual neurons. Also, even if the external circumstances are actually determined, due to our limited knowledge, they appear somewhat random to us.

As an example of how human behavior on a certain level is deterministic, a person who gets punched in the face will almost certainly experience either fear or anger rather than joy (meaning that the emotional response is not random). So, our emotional responses are fairly easy to predict. And our emotional responses get our thinking processes started. So, for instance, a punch to the face triggers pain, which perhaps triggers fear when the person realizes he's being attacked, which triggers thought processes aimed at avoiding a potential second blow, which are then followed by actions.

However, the exact manner in which an event is perceived or acted on might be somewhat random. What if a certain state of mind might cause one neuron out of a thousand to behave in an unpredictable manner (it may or may not fire), due to quantum fluctuations which are truly random. Maybe this might have some minute effect on the final result, such as by noticing or not noticing the color jacket of an attacker, or the exact position of the next footstep.

Another interesting thing about the human mind is that it can think about itself. We can think about what our values are or what the outcomes of previous choices were, and thus value things differently than we did in the past. So, as an analogy, we are like a computer program that has some capacity to rewrite its own code.

So, I think of our control system as something like a mostly deterministic algorithm, but with the special property of having access to its own source code, and with some small degree of true randomness somewhere in the process. So, the result might be that when we have many experiences, we typically respond to them in a predictable way, but one day we might randomly have a change of heart and become a somewhat different person. Now, if this "randomness" comes from predetermined external circumstances, then it only appears to be random. But if it comes from quantum fluctuations in our own minds, then it truly is random. Now, I don't know if this is consistent with what theists would think of free will, but it would explain how it might be possible that a person might make an unusual choice which maybe not even God himself would be able to predict*.

*If God is like a computer programmer, then he might choose on purpose to add a true random number generator (like what appears to be the case for quantum particles), or maybe add a special type of thing called "Free will" which is neither determined nor random, and in either case, he would not be able to predict what would happen before it happened. This would not diminish from his omnipotence, because he chose on purpose to make it this way. In a similar way, you wouldn't say that a programmer was necessarily incompetent for adding a random number generator to his code. Now, if God exists outside of time, it might be the case that he still has foreknowledge, not because he's writing the books of our lives for us, but because he can finish reading the book before we have finished writing.

Of course, this is all just speculation. It was just interesting to me that you can come to some idea that's similar to free will using only reasonable speculation from known physics.