Jerry Coyne as a new post up on free will.
One of the recurrent arguments made by free-will “compatibilists” (i.e., those who see free will as being compatible with physical determinism), is that those of us who are incompatibilists—in my case, I think people conceive of free will as reflecting a dualistic “ghost in the brain,” and find that incompatible with the determinism that governs our behavior—is this: “Nobody really believes in dualistic free will—the sense that one could have done otherwise. Thus, invoking your kind of incompatibilism is accepting a form of free will that nobody espouses. So why bother to beat a dead horse?”
Actually, as a compatibilist myself, I’ve never made this argument, and I don’t really see it that much from the compatibilists I’ve read. But anyway, I’m more interested in something else Jerry wrote.
He looks at a study that in a questionnaire that posited two universes. In universe A, everything is deterministic. In universe B, everything is deterministic except for human decision making. The study then goes on to ask the respondents questions with interesting results. I recommend reading Jerry’s post for the details.
But after covering those details, he makes this assertion:
To me, the data show that the most important task for scientists and philosophers is to teach people that we live in Universe A.
Except that we don’t. Oh, our universe has a lot in common with universe A, but A is not the one we live in. I covered this in detail in another post, but the TL;DR is that quantum uncertainty does affect the macroscopic world. If it didn’t we wouldn’t even be aware that it existed. And the fate of Schrodinger’s cat in the famous thought experiment is not determined prior to the cat being placed in the box, in other words the cat’s fate wasn’t set at the big bang.
Of course, given how deterministic the macroscopic laws of nature have been shown to be, in nature those effects generally would have to be incredibly small, within the margin of error of our measurements. But that’s all it would have to be for the butterfly effect to kick in, snowballing in complex dynamic systems to eventually make those systems inherently unpredictable, even in principle.
This is one of the reasons why I’ve said before that determinism and free will are really separate issues. If you define free will as indeterminism, you’ve cracked the door open to libertarian free will. Now, I don’t personally think quantum uncertainty rescues libertarian free will, since there’s nothing in that uncertainty that anyone could take credit for. But if you’re basing your opposition to libertarian free will solely on determinism, you should be aware that determinism isn’t as certain as many assume.