Archive for September, 2012

The precariousness of libertarian free will


I’d like to give you a glimpse of how I view free will and why.

This will not be a strictly formal philosophical argument. I have to admit some non-rational reasons for holding the position I hold. (Not irrational, I hope – I try not to contradict myself or the evidence, but you can’t ground every motivation in a reason that is itself grounded. Sooner or later, you have to accept something just because.)

I’ll start with a label: I am a determinism agnostic. I mean, I really don’t know whether our universe is completely governed by deterministic laws of cause and effect, or if there is some corner of real non-determinism in it. Not only that, I suspect it will forever remain impossible to know this absolutely.

Certainly a great deal of the universe’s behaviour is deterministic, from the cosmic-scale laws of gravity to the microscopic laws of cellular biology and chemistry. But is there some corner of indeterminacy? Some part of the universe’s behaviour that isn’t completely pre-destined based on prior causes? Some think the quantum world gives us that, in the apparently random variations of position or velocity observed at the smallest levels. In counterpoint to this idea of undirected indeterminacy is the hope of many that we – and perhaps other, more powerful players in the universe – have a ‘get-out-of-determinism-free’ card in the form of libertarian free will.

I don’t know. Looking at the trend of our understanding of the universe, and acknowledging my own aesthetic inclinations, I would guess not. I suspect it’s determinism all the way down. But I don’t know.

So does that mean I have no way to really decide whether or not we have libertarian free will? That I’m just going with my gut on this?

I’ll be honest: that’s part of it. But I also have two more substantial reasons for sticking with my compatibilist stance: one epistemological and one pragmatic.

The epistemological reason is this: it is possible to have positive evidence that event A is caused by event B; but it is impossible to have positive evidence that A is not caused by anything. Positive evidence for B causing A would be something like this: I usually observe A to follow B, and when I run an experiment to manipulate whether B occurs or not, I find A only occurring after B, but not after other events*. But what would show that A has no causal determiner? Nothing. Literally. The best I can ever hope for on that score is that, after a whole lot of honest searching, I fail to find some causal determiner of A. I can never be sure that a causal determiner isn’t just around the corner, and I can never exhaustively test all of the possible causes. So my best proof is nothing – no actual evidence contradicting the idea that A is undetermined, but no evidence confirming the idea either.

So libertarian free will can, in principle, be shown not to exist; but it can never, even in principle, be shown to exist.

Which brings me to the main pragmatic reason for preferring a compatibilist over a libertarian approach to free will. Someone who adopts a libertarian stance must beware the day that evidence is found to undermine that stance. Some function central to questions of free will may be found to have a clear, irrefutable physical cause – decision-making, execution of intentional action, whatever**. Libertarians are banking on the immediate physical exercise of free will having no determinate physical cause, but as described above they can never prove it. They can only declare that it hasn’t yet been disproven.

The compatibilist is safe in two ways. First, as mentioned above, it is impossible to conjure positive evidence against determinism. Second, even if such proof were possible, the compatibilist is not committed to determinism. Compatibilism simply claims that meaningful free will is compatible with a deterministic universe, not that it requires such a universe.

So, on the one hand are the libertarians, who could lose a key foundation of their stance any day if the right evidence is discovered. This seems to be a very precarious position to be in. On the other hand are the compatibilists, whose stance is secure under any empirical evidence that we might reasonably anticipate.

That, in a nutshell, is why I prefer a compatibilist stance:

  1. It is more aesthetically pleasing to me. In other words, my gut leans in that direction.
  2. It is more empirically supportable: any evidence on the question is either inconclusive or supports determinism.
  3. It is more pragmatically reliable: knowledge about the real world is very unlikely to undermine the stance, while such knowledge could easily undermine the libertarian stance.

So what does the world look like from this perspective? How do I fit myself into this picture as a meaningful actor in my own life? I’ll try to give you some answers on that soon. Stay tuned. For now, why don’t you let me know what you think? Do you agree? If you agree, do you lean toward compatibilism or do you still prefer to bet on libertarianism? What, honestly, do you think influences your view of free will?


* There are more subtleties to demonstrating causality, and it would never be absolute proof that A is caused by B, but it is possible to get strong evidence in favour of that hypothesis.

** Indeed, such evidence may already be trickling in. For example, there was a study in 2008 and another in 2011 that showed the “moment of decision” as experienced by individuals could be anticipated by a machine watching brain function (see here and here for details).