One strand in the consequence argument for incompatibilism
Suppose that determinism is true, and that I just put my hand down on my desk. As a compatibilist, I claim that this is a free but determined act. I was able to act otherwise, for instance to raise my hand. But there is a true historical proposition H about the intrinsic state of the world long ago, and a true proposition L specifying the laws of nature, such that H and L jointly determine what I did, and jointly contradict the proposition that I raised my hand. If I had raised my hand, then at least one of three things would have been true: contradictions would have been true, H would not have been true, or L would not have been true. So if I claim that I am able to raise my hand, I am committed to the claim that I have one of three incredible abilities: the ability to make contradictions true, the ability to change the past, or the ability to break (or change) the laws. It’s absurd to suppose that I have any of these abilities. Therefore, by reductio, I could not have raised my hand. – David Lewis
So goes the classic ‘consequence argument’ for incompatibilism, the thesis that free will is inconsistent with a deterministic universe. Against the consequence argument, Lewis goes on to point out that there are two different kinds of counterfactuals concerning the possibility of my raising my hand:
A: If I had raised my hand, either the state of the past or the laws of nature would have been different
B: If I had raised my hand, my act would have caused the past or the laws of nature to change
B is plainly absurd; one could not say that I ‘could’ raise by hand on the basis of B, and compatibilists do not say so. A, however, is perfectly all right on the determinist thesis, and incompatibilist ought to readily admit so. Now, with A there comes also an ability which I can be said to have, which I shall call A1:
A1: I am able to do something, such that if I did it, the state of the past or the laws of nature would have been different
I agree with the compatibilist that this represents a genuine ability I have. There is nothing contradictory in claiming anyone has such an ability, so I see no reason to think that it doesn’t represent a genuine property. The compatibilist claims that this argument for incompatibilism fails because it equivocates between the ability A1 which I do have, and the corresponding ability B1:
B1: I am able to do something, such that if I did it, the state of the past or the laws of nature would have been caused by my doing it
Against ability B1, the argument goes through*. But that, so says the compatibilist, is not what is at issue for we have abilities of the A1-type and those are good enough for making us free. Those who know me more than a little will be aware of my general disdain for arguing over definitions – if you want to call compatibilist freedom ‘free will’, then you are very welcome to make that stipulation. But the incompatibilist has available what I believe to be a very strong response, which is to say that the abilities such as A1 are morally irrelevant. For example, I have an A1-type ability to flap my arms and fly. I am able to flap my arms and fly, such that if I did it, the state of the past or the laws of nature would have been different. But it would be ridiculous to be accused of failing to act if I neglect to save someone from falling out of a building on the grounds that I ‘could’ have flapped my arms and flown to save them. So if we then extend this point to classic cases of, say, a child drowning in a pond who I fail to jump in and save because I didn’t want to get my clothes wet, the incompatibilist will make the analogous point which is my A1-type ability to jump in the pond and save the child is not a morally relevant one. It is of exactly the same kind as my ‘ability’ to flap my arms and fly, and I fail to see the morally relevant different between them except that in the save-the-child case we very much believe that I am morally responsible and so we just work backwards to get the right answer. But this is no way to do philosophy, for surely the onus is on the compatibilist to show why we should make a distinction.
I therefore conclude that while the consequence argument doesn’t necessarily succeed against it’s intended target – free will – it does make a powerful case for the incompatibility of moral responsibility with a deterministic universe. Indeed, I have often wondered whether it would be a big step forward in the debate over free will if we realized that what we are really arguing about is moral responsibility.
In philosophy, when we are trying to understand a concept or figuring out whether it actually applies as much as we initially believe it does, we can often get confused by two different ways of proceeding. One way is to look at the ordinary cases of the things we call ‘freedom’, ‘knowledge’ etc. and then see what is in common with those cases. Another way is to look at the kinds of reasons we give for or against the concept applying to a particular case. The problem is, these two ways of looking at it tend to come into conflict. In the case of freedom/moral responsibility – and, I would argue, in the case of knowledge – we have a conflict between our ordinary applications of the concept and the kinds of reasons we have for giving and (especially) denying that the concept applies. Sceptics about knowledge and moral responsibility say that if we consistently applied the kinds of reasons we give for denying that someone has knowledge (e.g. they haven’t ruled out all the possibilities) or is morally responsible (e.g. I can’t change my genes, so whatever my genes cause is something I am not responsible for) then we will end up denying that the anyone knows or is responsible for very much at all. It seems as if we either have to give up a whole lot of common sense thinking about who knows or is responsible for what, or we have to arbitrarily limit our application of the reasons we give for the concept not applying.
It strikes me that philosophy cannot tell you how to decide between those two, only that we must if we want to be consistent in our thinking.
*This very brief exposition of the consequence argument is indebted to Kadri Vihvelin’s excellent “Arguments for Incompatibilism” entry at the Stanford Encyclopedia of Philosophy