Today my victim is Hume. He is famously a compatibilist, believing that free will is compatible with determinism. But is this really what he believes? It isn't clear to me that he believes in either free will or determinism, and 'neither...nor' is not 'both...and.' If we define determinism, as I believe Tommi Uschanov once did, as the theory that every event has a cause, then Hume would not be a determinist if he did not believe that any event has a cause. And surely some people read him this way. Certainly some people read him as denying that we have free will, since he talks about the liberty of not being in chains rather than freedom of the will, and this (our not being in chains) is not what defenders of free will typically have in mind.
So, what does he actually say? This sounds pretty deterministic:
Everyone agrees that matter in all its operations is driven by a necessary force, and that every natural effect is so exactly settled by the energy of its cause that in those particular circumstances no other effect could possibly have resulted from that cause.But he also says this:
The necessity of any physical or mental action is not, strictly speaking, a quality in the agent; rather, it resides in the thinking or intelligent onlooker, and consists chieﬂy in the determination of the onlooker's thoughts to infer the occurrence of that action from some preceding eventsWhich sounds as though he is denying that there is any necessary force in any matter that drives its operations. The necessity is in the mind of the beholder, much as the badness of murder lies not in the act, according to Hume, but is a kind of function of the heart of those who contemplate the act. Because we all have much the same minds we all agree that murder is bad and that determinism is true. But it isn't really. (Kant then tries to solve this problem by claiming that the matter in question also exists only in the mind.)
And what of liberty or free will? Everyone knows that Hume says this:
I think less attention is paid to this passage:By ‘liberty’, then, we can only mean a power of acting or not acting according to the determinations of the will; i.e. if we choose to stay still we may do so, and if we choose to move we may do that. This hypothetical liberty—·‘hypothetical’ because it concerns what we may do if we so choose·—is universally agreed to belong to everyone who isn’t a prisoner and in chains. There’s nothing to disagree about here.
liberty, when opposed to necessity, is nothing but the absence of that determination ·in the onlooker’s thought· and a certain looseness or indifference which the onlooker feels in passing or not passing from the idea of one event to the idea of a following event.Liberty, too, is in the mind of the beholder, according to this. Hume seems to think it is rather illusory, but that is what he says it is. If this is right then liberty is not compatible with necessity at all. The onlooker's thoughts either have the determination in question or they don't. If they do, the agent's actions are necessary. If they don't, they are free.
I'm sure this has all been said before unless it is just badly wrong. But I wonder whether it relates to why (as I recall) Wittgenstein, in writing about free will, focuses so much on predictability.