Tuesday, 30 October 2012

Determinism and chaos

I have been listening to a talk recorded at Portsmouth Skeptics in the Pub, and published via the Skepticule podcast.  It was Jonathan Pearce talking about free will and determinism.  He counted how many of the audience might be convinced that we do not have free will at the beginning and the answer was around two thirds.  This had changed by the end.  I'm not going to recount his talk, but just talk about the things that have always bothered me about determinism.

Determinists argue that the whole of the future is determined - albeit not necessary pre-determined by a specific entity.  As such they try to convince us that we don't really have free will.  They often use masses of 'evidence' to convince us - and it doesn't convince me.

The evidence comes from the interpretation of results of experiments which seem to show that (for example) our muscles prepare for movement before our minds decide to make the movement.  At first sight these ideas seem compelling, but then you realise that the results are open to interpretation in more ways than one.

Seemingly 'unconscious' actions only suggest that there is no central 'me' who acts like a CPU in a computer.  However, when you consider that our inner awareness is clearly highly distributed through the brain, and that the brain functions fast enough for delays not to be noticeable in everyday life, you realise that evolution did rather a good job.

Worse still, I can't believe that determinists have such a naive view about the predictability of the future state of the universe.  I see this on several levels:
  • Even on the basis of a truly complete knowledge of the state of every particle and of all the energy in the universe, they miss an important point - namely chaos.  Chaos theory acknowledges that even the tiniest deviations from what can (in principle) be measured, will lead to a fundamental unpredictability.  It is unavoidable.  Increasing the power of your computer only delays the moment of unpredictability.
  • Moving into the quantum physics regime (and in this case I am not using the quantum physics metaphor to prove anything, but to question something) they neglect (or deliberately misunderstand and ignore) Heisenberg's uncertainty principle.  You just can't know everything about the universe as it is just now.  Whether we really understand quantum mechanics or not, it has shown itself to be much better in the predictions business than the philosophy of determinism.  I know where I would put my money on this argument.
  • This is not even to mention quantum fluctuations . . . particles and their anti-particles being created spontaneously from a quantum vacuum.
So let's face it.  The future is not actually determined by the present state of the universe except that it is like weather forecasting.  We can fairly reasonably predict trends for the near future, and we can see a final end to the universe as a huge expanse of cold darkness.  But the details get more hazy as the future unfolds.

My free will to publish this post - or not - can't seriously be questioned.

. . . and Pearce's talk was very interesting, even if (Note: IF) his own views are entirely fallacious! For a philosopher that is not an insult but a challenge.

Small note:  Listen to the podcast to see how the opinions had changed by the end of his talk.  I suspect that he was not expecting the reaction of an audience of skeptics!


Jonathan MS Pearce said...

hi there

Thanks for those comments.

Just a quick point before returning to this later. Chaos theory IS deterministic. Small variations have a large end effect - but they don't 'change' anything. The sheer volume of variables makes the system practically unpredictable, but it is still theoretically predictable. As wiki states:

"Small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for such dynamical systems, rendering long-term prediction impossible in general.[1] This happens even though these systems are deterministic, meaning that their future behavior is fully determined by their initial conditions, with no random elements involved.[2] In other words, the deterministic nature of these systems does not make them predictable.[3][4] This behavior is known as deterministic chaos, or simply chaos."

Jonathan MS Pearce said...

On QM, most physicists adhere to the Many Worlds Interpretation, a deterministic interpretation. The field is split.

Of course, the talk was on free will as incoherent. It does not need determinism. Near-determinism as espoused by people who do adhere to the HUP, like Hawking, still refutes free will, since an agent cannot have ownership over random.

Jonathan MS Pearce said...

In other words, you have not shown that you did, indeed, have free will to write that!

You see, free will is unable to be established philosophically, irrespective of the science.

eg http://en.wikipedia.org/wiki/Dilemma_of_determinism

(philosophical causality)