Wednesday, August 24, 2011

The Problem of Free Will (what's the problem again?)

Are we the authors of our own actions? Do we have free will? Whether this question can be answered in the affirmative has far reaching consequences for moral theory, political discourse, and even our interpersonal relationships.

At first glance it seems like a textbook example of a question so stupid only a philosopher could ask it. Of course we are free. We experience our free choice all the time, in big and small decisions. We decide what to have for breakfast, what to wear, what careers to pursue, who to marry, and a whole host of other things. What could be more obvious than that we have free will? It turns out, though, that when you look closely at the idea of free will, especially in light of our ideas about causation, the question isn't nearly as stupid as it looks.

The core notion at issue is fairly straightforward, I think, but let's be clear what we are talking about when we say a decision (or choice) exhibits free will. Here's one way to formulate the issue that I think captures the everyday intuition of what it means to say we are free:
For a decision to be an act of free will, it must be possible that the agent could have decided otherwise, even if all the events leading up to the decision were the same.

This ability to do otherwise, I think, lies at the center of the free will debate. In moral, legal, and interpersonal affairs we want to know whether people could have done otherwise than they have done. It has implications for responsibility and punishment, because we don't think of someone as responsible for an event if there is genuinely nothing they could have done differently.

With that in mind, let's put together a quasi-formal version of the intuitive argument that we all implicitly endorse when thinking about free will in a casual way:
Argument for Free Will (F)
FP1. We have introspective evidence that we have free will (i.e., we experience ourselves as having the ability to have done otherwise)
FP2. Introspective evidence is reliable
     FC. Therefore, we have free will
I think something very much like this argument is at the core of our confidence that we are free. Everyone knows the feeling of being free; we all have the experience of deliberating, or weighing our options, and then choosing the action we want to take. So the first premise (FP1) seems true. FP2 appears to be equally unassailable. How could we be wrong about our own feeling of freedom? So the conclusion (FC) appears to hold.

But how does this intuition relate to our thoughts about causation? When we think about choice, we think about it as having an effect in the world. Our ability to choose freely makes our choices causes of other events in the world. The material world may be deterministic, and effects may even follow regularly from our choices, which serve as causes. But our choices are not necessitated in the same way as physical events, right? This intuitively plausible line of thought starts to breakdown when we think about the mechanisms by which this free choice might operate.

What sort of a thing is a choice? How is it related to the physical world, if it is not itself physical? How can we account for its causal ability? If we adhere to physicalism (i.e., the view that all facts are physical facts), then here's the problem in a nutshell:
Argument for Determinism (D)
DP1. Decisions are mental events
DP2. Mental events are physical events
     DC1. Decisions are physical events

DP3. Physical events are fully determined by preceding physical events or physical states*
     DC2. Decisions are fully determined by preceding physical events or physical states

DP4. Events that are fully determined by preceding events could not be otherwise than they are
DP5. For a decision to be an act of free will, it is possible that the agent could have decided otherwise
     DC3. There are no acts of free will
DC1 follows DP1 and DP2 by straightforward reasoning. DP3 is stipulated by physicalism; DC2 follows from DC1 and DP3. DP4 is basically the definition of "determined." DP5 is essentially our earlier formulation of the necessary conditions for a decision to be free. DC3 follows from DC2, DP4 and DP5. So, we aren't free, then.

One venerable old philosophical strategy is to deny DP2 (i.e., to deny physicalism), and assert mind-body dualism. This is the obvious approach, especially if we want to preserve the notion of the immaterial soul. Descartes, for one, thought that merely by conceptual analysis the divide between mind and matter could be established. The concept of thought simply doesn't enter into the concept of matter, which is made up of our notions of extension and solidity, etc. Since mind can be thought of without the idea of matter, the two simply must be really independent of one another. But unfortunately for the dualist there is substantial evidence that our mental states are indeed physical states (aside from the fact that conceivability arguments fail to generate true facts about the world). Take as just one example Phineas Gage, who was a walking refutation of dualism. Brain injury essentially turned him into a different person altogether. Add to that the fact that our judgement is affected by drugs and alcohol, fatigue, etc. and arguing that the mind is independent of the body becomes problematic to say the least. Defending dualism is a much bigger challenge than Descartes thought.

So, if we are convinced that dualism is false, then the only other way to avoid the deterministic conclusion is to try to argue against the causal closure of the physical, which is essentially to argue that almost everything we know about the natural world is wrong.

We're left with two compelling intuitions, that we are free and that the world operates by physical causes, but that don't appear to be compatible. I don't know which side is right, but I plan to try to think it through in public over the next few weeks.

There are two broad categories of philosophical positions on free will, incompatibilism (which includes both determinism and the various forms of voluntarism or libertarianism) and compatibilism. Like everything I write about, the topics are far too broad to be adequately addressed in blog posts. But what I hope to do in some future posts is sketch the terms of the debate in a little more detail and look at some historical attempts at solving the problem. That's the plan, anyway.
*If we were being pedantic, DP1 is strictly false, because there is a class of subatomic or quantum events that are genuinely uncaused (i.e., random). So DP1 and all the other premises and conclusions would have to be suitably revised to include the provision that decisions are not free if they are caused by random quantum fluctuations. But since the idea that our decisions are random quantum fluctuations isn't any friendlier to free will than determinism, let's not be pedantic.

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