1) If I don’t have free will, then I can’t choose what to believe.
2) If I can choose what to believe, then I have free will [from 1]
3) If I have free will, then I ought to believe it.
4) If I can choose what to believe, then I ought to believe that I have free will. [from 2,3]
5) I ought, if I can, to choose to believe that I have free will. [restatement of 4]
He remarks in the comments:
I’m taking it as analytic (true by definition) that choice requires free will. If we’re not free, then we can’t choose, can we? We might “reach a conclusion”, much like a computer program does, but we couldn’t choose it.
I understand the word “choice” a bit differently, in that I would say that we are obviously choosing in the ordinary sense of the term, if we consider two options which are possible to us as far as we know, and then make up our minds to do one of them, even if it turned out in some metaphysical sense that we were already guaranteed in advance to do that one. Or in other words, Chappell is discussing determinism vs libertarian free will, apparently ruling out compatibilist free will on linguistic grounds. I don’t merely disagree in the sense that I use language differently, but in the sense that I don’t agree that his usage correspond to the normal English usage. [N.B. I misunderstood Richard here. He explains in the comments.] Since people can easily be led astray by such linguistic confusions, given the relationships between thought and language, I prefer to reformulate the argument:
- If I don’t have libertarian free will, then I can’t make an ultimate difference in what I believe that was not determined by some initial conditions.
- If I can make an ultimate difference in what I believe that was not determined by some initial conditions, then I have libertarian free will [from 1].
- If I have libertarian free will, then it is good to believe that I have it.
- If I can make an ultimate difference in my beliefs undetermined by initial conditions, then it is good to believe that I have libertarian free will. [from 2, 3]
- It is good, if I can, to make a difference in my beliefs undetermined by initial conditions, such that I believe that I have libertarian free will.
We would have to add that the means that can make such a difference, if any means can, would be choosing to believe that I have libertarian free will.
I have reformulated (3) to speak of what is good, rather than of what one ought to believe, for several reasons. First, in order to avoid confusion about the meaning of “ought”. Second, because the resolution of the argument lies here.
The argument is in fact a good argument as far as it goes. It does give a practical reason to hold the voluntary belief that one has libertarian free will. The problem is that it does not establish that it is better overall to hold this belief, because various factors can contribute to whether an action or belief is a good thing.
We can see this with the following thought experiment:
Either people have libertarian free will or they do not. This is unknown. But God has decreed that people who believe that they have libertarian free will go to hell for eternity, while people who believe that they do not, will go to heaven for eternity.
This is basically like the story of the Alien Implant. Having libertarian free will is like the situation where the black box is predicting your choice, and not having it is like the case where the box is causing your choice. The better thing here is to believe that you do not have libertarian free will, and this is true despite whatever theoretical sense you might have that you are “not responsible” for this belief if it is true, just as it is better not to smoke even if you think that your choice is being caused.
But note that if a person believes that he has libertarian free will, and it turns out to be true, he has some benefit from this, namely the truth. But the evil of going to hell presumably outweighs this benefit. And this reveals the fundamental problem with the argument, namely that we need to weigh the consequences overall. We made the consequences heaven and hell for dramatic effect, but even in the original situation, believing that you have libertarian free will when you do not, has an evil effect, namely believing something false, and potentially many evil effects, namely whatever else follows from this falsehood. This means that in order to determine what is better to believe here, it is necessary to consider the consequences of being mistaken, just as it is in general when one formulates beliefs.