Are compatibilism and incompatibilism compatible?
by Pedro Fonseca

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 -> F

When 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.

On the other hand, if we think that we are free only if our desires are not determined, the question about our freedom becomes ‘where did the D came from?’ And we will want to know if the D arose from a sequence of causes, or if it just popped up from nowhere to be seen.

pop!  -> 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

pop! -> D

is 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.

On the other hand, if the incompatibilist would use a version of free will based on the ability to perform, he would certainly be wrong. For instance, it is sometimes said that if determinism is true than given any distant past state of the universe, and set of physical laws, it is already determined what I am going to do in the next five minutes (or decades). It is then said that, since I have no control on what happened millions of years ago, and also on the laws of the universe, I have therefore no control on what is going to happen to me in the next five minutes, and therefore I am not free. But, if we are speaking about ‘performance’ free will, this argument is irrelevant. If we were speaking about control in the poppiness version we would be right. Because, in that version, ‘control’ has to do with ‘true’ desires – the ones that pop up and are not determined – being able to determine future events. If past events entirely determined future events then the pop that is produced now cannot influence the future and therefore we are not free. But, in the performance perspective, control has obviously nothing to do with breaking causal chains. We will analyze this in a subsequent text, but for now let«s just notice that the argument from past states of the universe only makes sense for a omniscient observer, it presupposes an omniscient point of view. From an omniscient point of view, that is indeed what we would find out if we lived in a deterministic world: we are not free, our actions have already been determined by past events. But, from our current point of view we have only knowledge of an infinitesimal part of reality. More specifically we do not know in detail what has happened, what are the laws of the universe, and what is going to happen (although we’re not completely clueless). However, when we perform we do expect that some sets of internal decisions are systematically correlated with sets of external events (for example moving the arm, opening the window and letting warm air come in). In a deterministic universe, such limited beings would represent the past as fixed and the future as open and uncertain. And they would also represent their decisions as based on their beliefs and attitudes, just as we do. And even if they would think that in fact they live in a deterministic universe (as the heirs of Newtonian dynamics did) they would have no choice but to continue to represent themselves and others as free, although, they would know that that kind of representation was due to their limited knowledge. I know of no better argument that can show that free will, in the sense of being able to fulfil desires, is incompatible with determinism.

Does this show that compatibilism is actually compatible with incompatibilism? Well... close, but not quite, at least as far as I can ‘see’. First of all there is a question of general attitude, compatibilists have generally an attitude towards life, etc, that is different from incompatibilists. So in a sense it might be difficult to be both at the same time. However, regarding the theories the situation is different. We have actually to show that a reasonable psychology can be built (in a possible world, of course) that incorporates both the poppiness and the performance factor. We would have both

pop!  -> 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...

A different question is to know if the pop up thing as any meaning at all. On the one hand it seems to be a logical absurdity contradicting the principle that ‘from nothing, nothing comes’. On the other hand, some current interpretations of quantum mechanics seem to look at nature that way, sometimes it is even said that the whole universe might have appeared from a fluctuation coming from nothing. (All kinds of particles are constantly coming up from nothing, they just disappear shortly after.) Obviously, this is just an interpretation, but if physicists thought it was a notion robust enough to be part of a fundamental theory of reality, why shouldn’t we.

Part of the reason is that coming up from nothing, in quantum mechanics, is associated with randomness, but randomness, even in ‘pop up’ free will is certainly not what we want. In a following text I will present a way in which I think we may find a point of equilibrium between the need to be determined by on the one hand nothing and avoiding randomness on the other.

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.