The European has an interview with Stephen Wolfram, (Many of you will know Wolfram as the designer of the famous computer program Mathematica.) The interview is mostly about progress in computer technology and its social benefits, but there’s one question about free will.
The European: This equation of nature and technology raises a few very hard questions about the definition of life, about free will, and about intelligence. What are the mathematician’s answers to those questions?
Wolfram: Let’s talk about free will first. The problem with human free will is that deterministic stuff is going on underneath, like the chemical processes in our brain, but that we don’t seem to act in a deterministic way. People used to think that deterministic processes must result in deterministic behavior, and that belief has underpinned much of the debate about free will. It’s the reason why the science fiction robots of the 1950s often speak very logically and behave very stupidly. The main scientific discovery is that it must not be like that. We can have simple deterministic underpinnings that result in very complex and seemingly random behavior.
Computational irreducibility is a key feature of life: We cannot grasp life through a formula, but must really simulate and observe it to see what happens. That’s how we as humans end up freeing ourselves from the deterministic rules. I tend to think that the concept of computational irreducibility is probably the answer to the philosophical debates of the past two thousand years about the relationship between free will and determinism. Philosophy is always at a certain distance to human behavior, so a lot of questions really get answered by science.
This answer seems to me misguided, because deterministic underpinning that can result in “unpredictable” behavior doesn’t bear on the classical issue of free will. First of all, “deterministic underpinnings” mean that behavior (including “choice”) is still determined, even if “complex and seemingly random.” After all, chaos theory, which is purely deterministic, yields systems whose outcomes are unpredictable if you don’t know the exact starting point. But chaos in our brain doesn’t give us free will.
As for this sentence,
I tend to think that the concept of computational irreducibility is probably the answer to the philosophical debates of the past two thousand years about the relationship between free will and determinism.
I simply don’t understand it. It seems to mean that if we can’t reduce behavior to predictive equations, we don’t have free will. But that doesn’t bear on the question of whether all our behavior is determined purely by our genes and our environments, and that we have no real choices.
Now my definition of “real choice”, i.e., free will, has always been this: if we could rerun the tape of life to the moment when we made a decision, with every particle in the universe in the same place at that moment, and yet we could have made a choice different from the one we did, then that is free will.
But, as some readers have pointed out, if quantum indeterminacy obtains, then perhaps rerunning the tape could yield a different decision, and that contradicts my assertion that I don’t accept quantum effects, which are random, as part of free will.
I then modified my definition to include “if you rerun the tape of life and could have consciously made a different decision at that moment, then you have free will.” But that doesn’t work either, for quantum effects might manifest themselves by making your decision seem conscious—especially if, as some experiments show, a conscious decision is simply how our brain perceives a decision that was really made unconsciously.
So for me (and I realize this isn’t true for others), whether we have free will or not boils down to whether quantum indeterminacy holds at the level of the brain and human behavior. Some people say yes; others say no. This is a matter for empirical study. But whether or not those effects exist won’t affect the conclusions of philosophical compatibilists: folks like Dan Dennett who claim that pure determinism is compatible with free will. To compatibilists, free will is completely independent of the issue of physical “causation.”