Can you be a compatibilist and incompatibilist at the same time? The answer seems to be yes since the two theories seem to apply to two quite different conceptions of free will. They might even be both true at the same time since a certain entity in a possible world may have the two different kinds of free will at the same time. In the following lines I will argue that incompatibilism is internally consistent only if it uses a specific notion of free will, which I dubbed ‘pop up’ free will. Compatibilism, by the contrary, is inconsistent when applied to pop up free will, but consistent if a more conventional version of free will is used. This means that arguing for compatibilism does not automatically show that incompatibilism is wrong and vice versa. It also means that many arguments used by proponents of one view against the other are ineffective because they are based on a conception of free will that is not shared by the other side.
Compatibilism is the theory according to which free will is conceivable in a world that evolves according to deterministic rules. Whereas, according to incompatibilism, free will is inconceivable in such a world. While there can be no doubt that the two theories, as stated, express apparently opposite thesis, it is not so clear that they are using ‘free will’ in the same sense. Part of the problem is that there is not a unique definition of free will (or related words like ‘freedom’, liberty’, etc). In political philosophy there is a well-known distinction between negative and positive freedom. Whereas negative freedom is concerned with the absence of constraints, positive freedom is concerned with the agent being truly unconditioned when making his choices.1 In an analogous way we can distinguish at least two different common usages of 'free will': we can either mean spontaneity (the ability to choose without being determined) or accomplishment (the ability to fulfil a certain choice or desire). We might call these two abilities the ability to freely choose and to freely accomplish. In both cases the freedom of the agent implies that he must not be determined by external factors, either in making or fulfiling his choices.
What we have then are two radically different characterizations of ‘free will’: in terms of accomplishment, free will characterizes the relation between a desire and the conditions for it’s actual fulfilment. Graphically, we would have something like
D -> FWhen there is no impediment that prevents F to arise we say the subject is considered to be free, which just consists in the subject being able to make the proper F’s appear according to the D’s he has. (The F of course, may be anything, including another D.) There seems to be no inconsistency between having free will in this sense and living in a deterministic world. Ordinary computers, for instance, might be said to have free will in this sense. The only thing we need is a program that represents its own current desires, the actual states of the world, and ways to fulfil its desires. Then either the program ‘sees’ that it can fulfil his current desires, and then he may attribute to himself the property of being free, either he his prevented from doing that, and then he may say he is not free.
-> D (a genuine free Desire coming from nowhere!)
cause1 + cause2 + cause3 + causen... -> D (the illusion of having a free Desire)Obviously, a computer cannot be free in this sense, although perhaps an electron can. It is not entirely clear however, that it is possible, in our universe, to have a system complex enough to represent itself as having desires, but subtle enough for its decisions to be partly made on the basis of quantum uncertainty (the only source of true poppiness that we know of). But, independently of what is actually the case, it should be clear that in any possible world where
-> Dis the case, determinism certainly cannot be true. So, if the incompatibilist is using this ‘pop up’ version of free will, he is certainly right in affirming that this kind of free will is inconceivable in a deterministic world. It should be clear that both compatibilism and incompatibilism are consistent when they are used with the proper notion of free will. Imagine a fiction story where there would be inhabitants of two different worlds. The first would have inhabitants capable of being free in the sense that they were able to perform what they wanted, although their wants were entirely determined by the previous states of that world. The second would have inhabitants that would create part of their desires ex nihil, ab initio, from nothing. Now, it seems clear that the first world could evolve in an entirely deterministic manner, but not the second, since at least some parts of it (the agents’ bodies) would have actions that did not depend entirely on what happened before in that universe (or anywhere else). Moreover, in both universes, its inhabitants could well act and represent themselves as being as free as we do.
-> D and D -> F (where F can also sometimes be a particular D)Now this doesn’t seem very difficult but it leads to a situation in which when you pursue your desires you are determined, although when you create them you are (sometimes at least) popping up. In both senses you are and are not free. When you’re popping up you are free according to the ‘pop up’ free will perspective, but not regarding performance free will since you are not actually fulfilling a previous desire (actually you would not be fulfilling anything). On the other hand, if you already have desires and are acting upon them, you are free in the sense of performance, but you are obviously not popping up. So...
1 Check Isaiah Berlin seminal work for a more detailed account of the differences between positive and negative freedom: “Two Concepts of Liberty” in I. Berlin, Four Essays on Liberty.