Deterministic but Unpredictable

A friend and I were discussing Douglas Hofstader’s new book “I Am a Strange Loop”, specifically his comments on Free Will. He tries to dismiss the entire philosophical exercise and focus more on the notion of “choice”, but it seems clear that at a deeper level he ultimately sides with pure determinism. This appears to be the emerging consensus of the scientific community as shown in this poll of “professional evolutionary scientists.” (Overall Hofstader’s book was a bit disappointing and somewhat derivative of his earlier work.)

At a spiritual level, it can be unnerving to think that all of one’s actions are, in essence, predetermined and could in principal be predicted if the initial conditions were known with enough accuracy. Henri Poincaré’s work on the famous 3-body problem though demonstrated over a hundred years ago that it is impossible to ever approach such a calculation—things may be deterministic but they are unpredictable.


Two other books that I recently read, Ivar Ekeland’s book “Mathematics and the Unexpected” and Nassim Nicholas Taleb’s snarky “The Black Swan” both deal in their own way with implications of unpredictability and discuss Poincaré’s work. Coincidentally both books highlight this difficulty by referencing the same detail from a 1978 paper by Professor Michael Berry called “Regular and Irregular Motion” which analyzed Poincaré’s insights in great detail.


On page 95 of that paper, Berry calculates that, given a billiard table, after only 9 collisions, in order to make a accurate prediction of the final state, the gravitational effects of the people in the room would need to be taken into account. After 56 collisions, the effects of a single electron at the edge of the visible universe would be required!

» Posted: Saturday, June 16, 2007 | Comments (6) | Permanent Link


“it can be unnerving to think that all of one’s actions are, in essence, predetermined and could in principal be predicted if the initial conditions were known with enough accuracy”

But what else could we hope for? Isn’t it that we want: who, or what, we are to determine our actions?

I want to think that my genetics + my environment + some good meals + some good books + some good intoxicants + some other (real) stuff —> me. Then me + a choice —> my decision. That is determinism, right? The alternative is just random and unpredictable and not particularly human.

» Posted by David S. on June 18, 2007 09:02 AM

It’s the nature of “a choice” that is the issue. The definition of “Free Will” I imagine most people assume is one where the decision making process is something they are in control of.

Determinism states that there is no actual controller per se, and hence no real “choice”; the decision is nothing more than the summation across the existing state of the underlying physical substrate. In classic Newtonian physics you could in principal figure out what the result would be given the initial conditions. Quantum mechanics of course adds a level of pure randomness to the mix which makes the final state indeterminable (even beyond the complications highlighted by Poincaré.) But in any case, determinism states that people are no more in control of their actions than a wave is in control of its rippling across a pond. We’re a localized reversal of the universal entropy, unwinding like a clockworks. Sure, we have fun while we’re doing it, but it may be more satisfying to imagine that we are in the driver’s seat and not just along for the ride (as enjoyable as that ride may be.)

All evidence certainly points toward Determinism. For example, Benjamin Libet has experiments that demonstrate decisions are set in motion in the brain ~500ms (!) before the person is aware of making them. (Which I had discussed here.)

Philosophers of science such as Martin Gardner (see his collection of essays “The Night is Large”) state outright that all evidence would seem to be against Free Will, but look to the weirdness of the quantum world as a potential way of decoupling from pure determinism. This is not to say that consciousness isn’t fully materialistic, i.e., an emergent property of the cells that make up the brain, but that somehow the as-yet-unknown mechanisms that give rise to consciousness allow for the kind of free will I’m referring to. Nobody has a mechanism which would provide for this of course…

» Posted by winter on June 19, 2007 10:16 AM

Perhaps it is not the definition of “choice” that is problematic, but the definition of “controller”. The I in me, if you will.

Certainly, Occam’s razor instructs us that we should stop looking for magic when there is no need. But it does not seem to me that we have given anything up by doing so. When you say, “the kind of free will I’m referring to,” I would like to know what exactly that is.

If I ask someone, “what do you mean by free will?”

They might answer, “I mean that I make choices—-who I am, what I know, everything that is me determines my choices.”

“Great,” I say, “that is what you have. Interestingly, it is, strictly speaking, deterministic.”

“Oh, well then, I mean something else… something more.”

“Well then, I can’t help you.”

To be honest, trying to construct some ontology to work with that includes a notion of free will worth caring about seems fruitless. There is an irreconcilable tension between defining the individual with free will and then defining free will as something separate. I would describe this in detail but the margins of your page styling don’t leave room enough for me to properly expound my thoughts.

Anyway, it strikes me that the hope for something supernatural—-and that is what this notion of free seems to require—-is like the hope that Earth is the center of the universe and the hope that humans are not simply another species resulting from evolution.

David S.

p.s. Keep up the good blogging.

» Posted by Anonymous on June 20, 2007 09:37 AM

As James Jeans said, “The question is not are we free but why do we think we are free”.
I believe the universe is deterministic yet unpredictable. Therefore, I am free to believe I am free.

» Posted by William Hill on July 23, 2007 06:55 AM

“…the hope for something supernatural…”

I have to plead guilty in this regard. While I see myself as a materialist in that I believe we are the product of our physical brains, a model of consciousness that allows ideas to emerge “de novo” would by some definition make us godlike.

“I believe the universe is deterministic yet unpredictable. Therefore, I am free to believe I am free.”

My previous comment aside, I think all evidence points in this direction.

» Posted by winter on July 23, 2007 01:47 PM

Limitations of a scientific theory of human consciousness

» Posted by David S. on May 1, 2008 09:17 AM