Determinism and free will

[Scott1328]

Even formally deterministic systems exhibit chaotic behavior. Newton's three body problem is a famous example.

It surprises me that rev is unable to grasp why making predictions is central to Dennet's concept of free will. It is how one evaluates the consequences of one's actions as one is choosing among alternatives.

[JimC]

Scott1328 wrote:

Even formally deterministic systems exhibit chaotic behavior. Newton's three body problem is a famous example.

It is formally classical (in the sense of not needing quantum theory), but can it be said to be truly deterministic? It is fully mechanical, in the sense that it only depends on simple physical forces, but given that, after a surprisingly short time, future positions and velocities of the objects simply cannot be calculated, even allowing to a universe sized calculator, I think we've left the Land of Determinism behind, Toto...

[Scott1328]

A deterministic system is a system whose future state is completely determined by its current state. It is chaotic if it exhibits these behaviors

Long term behavior is difficult or impossible to predict: Even very accurate measurements of the current state of a chaotic system become useless indicators of where the system will be. One has to measure the system again to find out where it is.

Sensitive dependence on initial conditions (a property noted by Poincare, Birkhoff, and even Turing): Starting from very close initial conditions a chaotic system very rapidly moves to different states.

Broadband frequency spectrun: That is, the output from a chaotic system sounds "noisy" to the ear. Many frequencies are excited.

Exponential amplification of errors: In any real world setting small amounts of external noise rapidly grow to control the sytem. If this noise is below measurement accuracy, so that an experimenter can't see or control the noise, then the system appears unpredictable. The microscopic "heat bath" is amplified to human scales.

Local instability versus global stability: In order to have amplification of small errors and noise, the behavior must be locally unstable: over short times nearby states move away from each other. But for the system to consistently produce stable behavior, over long times the set of behaviors must fall back into itself. The tension of these two properties leads to very elegantly structured chaotic attractors.

https://www.exploratorium.edu/complexit ... chaos.html

[JimC]

Scott1238 wrote:

A deterministic system is a system whose future state is completely determined by its current state.

This is stated mainly to attempt to rule out systems where other outside influences, material or otherwise, become factors in affecting the final state. However, it can only apply to a completely isolated system, which cannot exist in the real universe (unless we mean the entire universe itself)

Consider the 3 body problem, known to be intractable to prediction, and a perfect example of a system exhibiting chaos. The diverging possibilities of future states are incredibly sensitive; if the system were started a second later, then the difference in initial state caused either by something classical, like the arrival of a minute gravity wave from somewhere else in the universe, or something in the quantum realm, like a minuscule difference in the position and/or momentum of an electron will be enough to cause a significant change in future states.

What I'm trying to get at is that "completely determined" is an unachievable (in a real universe) state of mathematical perfection. It has as much reality as a Platonic form.

[laklak]

I have, on occasion, and by an act of what appears to me to be "free will", engaged in behavior that can best be described as chaotic. This generally results in someone yelling "WTF do you think you're doing?!" or "PUT YOUR HANDS ON YOUR HEAD SCUMBAG!".

[pErvinalia]

Enough is known about chaotic behaviour, in a wide variety of systems, to be sure that it is not rare, but frequently occurs in non-linear systems. Neural networks will not always generate the same output from different inputs that, as far as our measurements suggest, are the same. (Can't give you a reference, but I have read accounts of such phenomena in a variety of books and New Scientist articles over the years). To me, this allows for some "wiggle room", not just for Dennett's version of free will (which can have a political dimension, but is not purely that) but also for a more classical version of free will.

I'd need to see an example to comment.

[pErvinalia]

Even formally deterministic systems exhibit chaotic behavior. Newton's three body problem is a famous example.

I've addressed before, and no one has rebutted it. Chaos isn't a concept about indeterminism. It's about compounding margins of error and the difficulty of computability, AFAIK.

It surprises me that rev is unable to grasp why making predictions is central to Dennet's concept of free will. It is how one evaluates the consequences of one's actions as one is choosing among alternatives.

You'll have to try and explain it in more detail.

[JimC]

Read "Chaos" by James Gleik - a really good account...

However, if any aspects of either the firing of neuronal networks, and/or the growth and subsequent trimming of the connections between neurones exhibits chaotic behaviour (in particular unpredictable future states), then we have sufficient grounds to reject the dismissal of classical free will, let alone Dennett's version. From all I've read about neural networks, chaotic behaviour can occur in certain conditions.

[pErvinalia]

But again, chaos doesn't refute determinism.

[Scott1328]

Who is attempting refute determinism? It is you have failed to demonstrate how determinism rules out free will

[pErvinalia]

Jim is.

[pErvinalia]

...

[pErvinalia]

Free will is:
The ability of an agent to predict, on occasion, and evaluate the possible outcomes of various alternatives and behave according to that evaluation. This then indicates that there are degrees of freedom; the better an agent's ability to predict and evaluate the more freedom it has. Sometimes, though all the prediction and evaluation in the world will not help if there are no alternatives, in such cases there is no free will. This is the gist of Dennett's argument in Freedom Evolves.

Going back to this definition, that means that my phone has free will because it uses auto-correct.

[Scott1328]

No. Try for a less lame reductio ad absurdum

[JimC]

Who is attempting refute determinism? It is you have failed to demonstrate how determinism rules out free will

As the OP of this thread argued, I'm saying that a combination of chaos (extreme sensitivity to initial conditions) plus quantum mechanics (uncertainties in initial positions/momenta) means that the extreme, Lagrangian version of determinism cannot stand. Not even a being with infinite perception and computational power (who cannot exist anyway) could, by "knowing" the exact positions & momenta of every particle in the universe at some point in time, compute future states to perfection. If real determinism is anything, it is that; an idealised declaration of an unrealisable mathematical perfection in a real, stochastic universe.

This lack of full determinism means that the classical objection to free will disappears. I concede that a lack of determinism is not necessary to allow for Dennett's version, which I think is a pragmatically useful way to encompass the idea of ethical choices by reasonably autonomous agents.