In an article at
Mind Matters neurosurgeon Michael Egnor discusses the debate between determinists (those who believe that there's no free will) and libertarians (those who believe we have free will). Egnor writes:
In a previous post, I argued that if determinism is true, we cannot have free will. That is, if everything we do is determined by the laws of physics and chemistry, there is no room for genuine freedom. In that respect, I am an “incompatibilist”—I don’t believe that free will is compatible with determinism.
What do I mean by determinism? Determinism, in the scientific sense intended here, is the view that for every moment in time, the state of the universe is completely determined by the state that immediately precedes it.
If you knew all of the details of the universe — the location and state of every particle — at any given moment, you could know with certainty what comes next. Determinism is more or less the view that nature is a machine. If we know the position of the gears, we can know the future with certainty.
The basic argument for the belief that our choices are
not free goes something like this:
- Every event in the physical universe is the inevitable consequence of prior causes (i.e. every event is physically determined).
- Our choices are events in the physical universe (i.e. they occur in the material brain).
- Therefore, our choices are the inevitable consequence of prior causes (i.e. they're determined by our strongest motives)
This is obviously a valid argument. If each of the premises is true then the conclusion follows, but it's not clear that either of the two premises is true, and the first premise seems, in fact, to be false. Here's Egnor:
In 1964, Irish physicist John Bell (1928–1990) published a paper titled “On the Einstein, Podolsky, Rosen Paradox”. In it, he observed that there is a way to test determinism at the quantum level by measuring the ratio of quantum states of particles emitted by radioactive decay.
Bell’s experiment has now been done many times, and the answer is unequivocal: determinism at the quantum level is not true. Nature is not deterministic.
The experiments showed that every quantum process entails some degree of “indeterminism”; that is, there are predictable probabilities but there is never certainty. If we knew the exact state of the universe at any given moment, we could still never know with certainty what would happen next.
Determinism in nature has been shown, scientifically, to be false. There is no real debate about this among physicists. So the question as to whether determinism, if it really existed, would be compatible with free will is merely an academic question, an interesting bit of metaphysical speculation.
If all this is true, then the first premise in the above syllogism is false and the entire argument collapses. It may still be that our choices are not free, of course, but, if so, some other argument is going to have to be employed to demonstrate that, and it's not clear what that argument could be.