Free Will vs. Predestination (12)

1 Name: Anonymous Scientist : 2009-04-28 15:24 ID:imaFwbtd

I was having a thought experiment the other day, and thought that it was interesting enough to share - and also ask you folks your opinions on the matter, and the ramifications it has on life.


  1. Human "Consciousness", actions, thought, and memory are all mediated and controlled by the Human Brain.
  2. Matter and Energy interactions could (concievably) be predicted perfectly into the future if all information at the present is known and all universal laws and constants were known.
  3. The Human Brain, as a part of the physical universe, could also be predicted.

At the moment of the universe's creation, everything that has happened, is happening, and will happen [Including this discussion] was inevitable and destined to occur, and free will is an illusion.

Now, there could be some problems with this mental experiment. First, not being a physicist, I'm not sure of the validity of my second assumption. Quantum Physics (I think) tells us that there is inherent probabilities in the interactions of particles, but is that truly random, or simply because we're not advanced enough to understand the laws that definitively determine a particle's behavior?

Any thoughts?

2 Name: Anonymous Scientist : 2009-05-03 12:32 ID:B91gbOcl

There's a more interesting question hidden there, is there true randomness?

If there's true randomness, then clearly we can't predict the future via the method you described, by taking everything into account and computing according to the laws of nature the next step.

Notice this does not answer whether we have free will or not. It is possible that which is truly random is not related to the human brain. Our thoughts could be the result of predictable chemical reactions. Randomness could affect our thoughts, but the outcome would still be predictable. That would mean brain-simulating AI is possible.

Leaving humans aside, you're talking about absolute knowledge. You assume there's someone with all the necessary knowledge (which amounts to infinite) to predict the future from knowledge of the present, and then you draw conclusions from that. You consider whether such entity exists or not, but you don't consider whether such entity could exist.

3 Name: Anonymous Scientist : 2009-05-04 12:50 ID:Heaven

all three of your assumptions might be (and probably are) wrong in the real world...

4 Name: Anonymous Scientist : 2009-05-04 16:46 ID:imaFwbtd


hmm, I didn't really think I was trying to assume anything about absolute knowledge, only that if all information was known, could an outcome be predicted. Whether there would be some machine or entity capable of calculating it is irrelevant.

I suppose I should have phrased it, does every reaction in the universe follow some natural law (even though we may not understand it yet)? If so, does it then follow that the Human Brain is just another reaction that could itself be predicted?

5 Name: Anonymous Scientist : 2009-05-04 23:52 ID:/o76f6SH

If and when the brain-predictitron is invented, you'll know the answer is, Yes.
If and when it is not invented, you'll know the answer is, Maybe.

6 Name: Anonymous Scientist : 2009-05-06 05:08 ID:+PvM45nQ

Well it depends on if you believe that the universe is infinite..
If so then everything that can happen is happening. Has already happened, and will continue to happen forever. Infinite universes mean that every possible outcome of any-thing is has and will happen at the same time and will continually happen somewhere forever.

7 Name: Anonymous Scientist : 2009-05-06 05:16 ID:+PvM45nQ

There is no physical way for a human to grasp this concept, seeing as we have never sent a human beyond the moon..
And truly know nothing about the universe

8 Name: Anonymous Scientist : 2009-06-22 03:52 ID:zEEPbpJi

The general consensus... maybe I shouldn't use that world... the strong majority opinion among quantum physicists is that even if we know ALL information in the universe, the random quantum behavior of every particle interaction would still be, purely, random. So the current idea in physics is that no outcome in nature can be specifically predicted; only a probability distribution of the outcome can be predicted.

But randomness isn't free will either. But if quantum interactions weren't actually random but somehow "free" in some sort of preternatural sense, there's no way for science to detect it.

But the nature of the interaction between mind and brain is such a giant mystery, it makes no sense to make your first assumption either. The arguments against free will seem as absurd to me as the arguments against an objective reality. Free will is one of the few things in existence that we can truly directly and intimately experience and reflect on. If anything deserves to be an axiom or assumption, I think it should be the existence of free will, along with the existence of the self and of external reality.

9 Name: Anonymous Scientist : 2009-07-10 19:24 ID:Ot7zjEn1

I've only done first year Uni Physics, but i have considered this very problem at great length, here are my thoughts:

  1. Agree entirely with first assumption
  2. There are many parts to this:

From a classical physics perspective, the universe is 100% deterministic. Thus your second assumption would be correct.
However, Classical physics is incomplete. Currently the greatest theory for understanding modern physics is taken to be quantum physics. Now I am not necessarrily saying that quantum physics is complete or perhaps even correct either, but at this point it is the best thing we have.
Now: in quantum theory, all particles are waves, and (I won't bore you with the details) due to this, it is impossible to know with 100% certainty both the location and the velocity of any particle (look up Heisenberg's uncertainty principle).
Now one could argue that it does not matter if we know both, all that matters is that they have both. The theory seems to imply that it does not actually have both unless measured which would render such an argument moot, but as previously, quantum theory is not perfect.
3. Assuming that all particles DO have both a certain location and a certain velocity at any certain time, then yes, I agree the brain could also be predicted. If not, they it cannot be predicted with 100% accuracy. (Though since our brains do not manipulate the quantum effects, and thus cannot control the randomness, they still probably are unable to actually exercise free will.)

Personally I think that it makes total sense that we can never know anything to 100% certainty, once you do alot of physics this much becomes apparent.
However, i do not believe that the fact that I know something is necessary for it to have happened or exist, thus I do believe that it is deterministic.

This has led me to 3 important realisations:

If we accept the possibility that a 'God' exists, then its interaction with this universe is dependant upon this argument!
If everything is deterministic, then the ONLY possible time that god MIGHT have interacted with the universe is at its very beginning. This means that it doesn't matter what you pray to god for coz he cant do a damn thing more!
Alternatively, there does exist true randomness, and this presents an opportunity for 'god' to interact with the universe subtly by ensuring that certain 'random' events turn out the way it wants.

I had once used your argument that it was possible to predict the future by knowing the conditions at any one time and having a perfect understanding of physics. I also knew that all possible variables must be calculated, thus the only way to predict with 100% certainty was to simulate the entire universe.
I imagined that a supercomputer of infinite power could simulate the entire universe in fast forward until it was viewing the future.
Unfortunately this hit a dead end when I realised that the computer would be required to simulate itself simulating itself simulating itself etc etc since it is a part of this universe, thus no matter how powerful the computer, you cannot possibly predict the future with 100% certainty even if you know exactly what the universe was like at one given point in time.

Less importantly, if the universe is deterministic, then there is only one possible way in which events can occur, thus there is no multiverse.

Anyways, philosophical or metaphysical food for thought =P

10 Name: Anonymous Scientist : 2009-07-11 15:25 ID:xbLLMI2g


I think the question is not if there is free will... but instead, what IS free will?

We obviously make some kind of 'choices'. But what are choices? Do we really know?

When you 'choose' between drinking chocolate milk or regular milk, did you actually make a choice, or do you just believe you did? i.e. did your subconscious mind weigh certain criteria and arrive at a specific preference of one over the other, or were you simply guided by a physiological 'craving' which would only allow you to go in one direction (making it somewhat of a non-choice but with the illusion of choice)?

11 Name: Anonymous Scientist : 2009-07-11 15:52 ID:xbLLMI2g

Continuation from above...

In addition, the way I see it, 'randomness' in thought or choice does not compute. as I fail to understand how we could engineer complex structures if our brains were very susceptible to true randomness. There may be some form of entropy involved but it will have a tendency to organize itself into order... otherwise I believe you'd be walking down the street and suddenly collapse and start eating mud or who knows what (and I'm sure some people with mental disorders have done it, but I mean average 'healthy' people)

12 Name: Anonymous Scientist : 2009-08-04 08:51 ID:rF7NaDLp


(3) But what about the observation? How can you determine observer and what exactly is observation? And then, what if free will is not actually about making choices but just determining one of variants or just being conscious, or being able to override basic chemical reactions of your brain, ie. when you become angry about something, happy etc. just because your brain released some substance and being able to "override" it with logical thinking (though it is still chemical reaction). But what if you assume existence of a soul and assume that randomness, choosing one or the other comes from that soul and brain is just a result of choices? Then soul would be the director, teacher, maker and human brain would be just student, work of the master. And free will would exist but we wouldn't really have it as we, as we are now, would be just something created by our souls, unless of course soul would manipulate with material world to a degree where we would start thinking about it. But this is rather religious and philosophical stuff which some of the people throw away immediately ;)

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