The randomness objection to libertarian free will holds that undetermined choices will be random and hence unfree. Some randomness-based objectors to libertarianism are compatibilists who think free will is possible, but requires choices to be determined (e.g., David Hume). Others think that free will is impossible (cf. Galen Strawson). I will offer an argument against the Humeans, those who think that freedom is possible but it requires determinism for the relevant mental events. Consider three cases of ordinary human-like agents who have not suffered from brainwashing, compulsion, or the like:
- Gottfried always acts on his strongest relevant desire when there is one. In cases of a tie between desires, he is unable to make a choice and his head literally explodes. Determinism always holds.
- Blaise always acts on his strongest relevant desire when there is one. In cases of a tie between desires, his brain initiates a random indeterministic process to decide between the desires. Determinism holds in all other cases.
- Carl always acts on his strongest relevant desire when there is one. In cases of a tie between two desires, his brain unconsciously calculates one more digit of π, and if it's odd the brain makes him go for the first desire (as ordered alphabetically in whatever language he is thinking in) and if it's even for the second desire (with some generalization in case of an n-way tie for n>2). Determinism always holds.
Gottfried isn't free in cases of ties between desires--he doesn't even make a choice. Our Humean must insist that Blaise isn't free, either, in those cases, because although Blaise does decide, his decision is simply random. What about Carl? Well, Carl's choices are determined, which the Humean likes. But they are nonetheless to all intents and purposes random. A central part of the intuition that Blaise isn't free has to do with Blaise having no control over which desire he acts on, since he cannot control the indeterministic process. But Carl has no control over the digits of π and these digits are, as far as we can tell, essentially random. The randomness worry that is driving the Humean's argument that freedom requires determinism is not fundamentally a worry about indeterminism. That is worth noting.
Now let's go back to Gottfried. Given compatibilism it is plausible that in normal background conditions, all of Gottfried's choices are free. (Remember that if there is a tie, he doesn't make a choice.) Suppose we grant this. Then there is a tension between this judgment and what we observed about Carl. For now consider the case of closely-balanced choices by Gottfried. Suppose, for instance, Gottfried's desire to write a letter to Princess Elizabeth has strength 0.75658 and his desire to design a better calculator has strength 0.75657. He writes a letter to Princess Elizabeth, then, and does so freely by what has been granted. But now notice that our desires always fluctuate in the light of ordinary influences, and a difference of one in the fifth significant figure in a measure of the strength of a desire will be essentially a random fluctuation. The fact that this fluctuation is determined makes no difference, as we can see when we recall the case of Carl. So if we take seriously what we learned from the case of Carl, we need to conclude that Carl isn't actually free when he chooses between writing to Princess Elizabeth and designing a better calculator, even though he satisfies standard compatibilist criteria and acts on the basis of his stronger desire.
What should the Humean do? One option is to accept that Gottfried is free in the case of close decisions, and then conclude that so are Carl and Blaise in the case of ties. I think the resulting position may not be very stable--if compatibilism requires one to think Carl and Blaise are free in the case of ties, then compatibilism is no longer very plausible.
Another option is to deny that Gottfried is free in the case of close decisions. By parallel, however, she would need to deny that we are free in the case of highly conflicted decisions, unless she could draw some line between our conflicts and Gottfried's fifth-significant-figure conflict. And that's costly.
Finally, it's worth noting that the objection, whatever it might be worth, against the incompatiblist that we shouldn't need to wait on science to see if we're free also works against our Humean.