A technical question about free will

[jogger08152]

Physicists:

Does quantum physics support, contradict, or not speak to the the idea that humans have free will?

Specifically, how does quantum indeterminacy affect the question of human free will? It seems to me that it ought to increase the likelihood quite a bit, relative to the classical idea of a universe in which, if the state of all things were known absolutely at any given point in time, the outcomes of all interactions could be calculated precisely, given enough computing power.

Thanks,
Jogger

[Skidoo]

If I understand you right, please explain how indeterminacy (of any sort) could cause or otherwise improve self-determinacy.

You volunteered this opinion, so I'm curious how you got there.

[jogger08152]

In classical physics, the supposition existed that if you could know everything about the universe at a given time (the "state" of the universe), you could use that knowledge (given vast, Godlike computing power), to precisely predict all future states of the universe (and could, I think, extrapolate backwards to predict all past states as well).

This idea, which I understand quantum physics to contradict, seems to me to be incompatible with free will: while I might believe, for instance, that I can either turn right at the next stop sign I encounter or instead proceed through the intersection, in fact, a precise prediction could have been made (theoretically) as to which direction I would "choose" 20 million years before my birth, or indeed, .0000001 seconds after the Big Bang. In other words, in classical physics, my "choice" would be predetermined, and therefore (at least it seems to me), not really a choice at all. The laws of physics and the "motion" of the universe would have determined (pre-determined, in fact, as in predetermined causally) my actions. This in turn would seem to proscribe the possibility of my having free will.

In quantum physics, as I understand it, the universe doesn't work deterministically, but instead is governed by probability. Simply, if you could know the state of the universe at any given time - but quantum physics applied - you could not use the knowledge to predict the future state of the universe. (Actually, I believe I may be expressing this incorrectly: quantum physics may deny the possibility of knowing the state of the universe in the first place.)

Again, disregard the difficulties of obtaining the knowledge and of making perfect predictions based upon it. The point is, in classical physics, with perfect observation and a powerful enough computer, you could do it. In quantum phsyics, you can't - I think. But I'm not sure. My understanding of all of this is limited - hence my request for clarification.

-J

[ChrisV]

Quantum physics implies some kind of hole in determinacy, but it depends on what interpretation you apply. In the Copenhagen Interpretation, the future is not predetermined, which is good news for free will. In other interpretations, such as the Transactional Interpretation, the future has in some sense already happened, as there are backwards in time signals in this interpretation. However it is still not possible to determine the future from the universe's present state.

[Nielsio]

[ QUOTE ]
In other words, in classical physics, my "choice" would be predetermined, and therefore (at least it seems to me), not really a choice at all.

[/ QUOTE ]


Choice is a causal mechanism.

[DrunkHamster]

I just finished writing a philosophy essay on this topic - I don't know that much about the physics, but philosophically it is very interesting:

You are really asking 2 questions: does physics support determinism (i.e. the thesis that a proposition A detailing the state of the universe at time t, and L the laws of physics together entail B, the state of the universe at some time after t.) This is not known conclusively - look here for an article on why.

The other question, which occupies philosophers much more, is whether or not if determinism were true free will would exist. The best people to read on this subject are Van Inwagen, Ayer, and probably Strawson. A nice web page by Honderich (who is closely involved in the argument) is here

[Skidoo]

[ QUOTE ]
Choice is a causal mechanism.

[/ QUOTE ]

Proof?

[jogger08152]

I can't follow the math in the first article; can you explain why we don't know whether physics supports determinism (or do you have a link to an explanation of this) in lay terms?

The second link looks promising; I just finished Determinism's Consequences -- The Mistakes of Compatibilism and Incompatibilism, and What Is To Be Done Now, and it seems most people take the existence of free will to be the axiomatic starting point (I haven't read any of the sublinks in part 8 yet though) and concentrate mainly on explaining its nature. Is this correct? In other words, it seems people are mainly interested in finding a way to allow determinism and free will to coexist because they believe they experience free will, and they think there is a good chance the universe is deterministic. This strikes me as kind of a weird approach: because the experience of free will is more compelling (to me) than the belief in a deterministic universe, I find myself thinking there must be something wrong with determinism. But then I don't see any need to rationalize the two, since if the universe is deterministic, there's no reason I can think of why it couldn't exist in such a way as to fool me into thinking I have free will even though I don't actually have it. (I don't think this is the case, mainly because of Occam's razor: most likely the universe simply isn't deterministic, which seems to gibe with quantum physics. Hence my original question.)

Anyway, thanks very much for your reply!

Best regards,
Jogger

PS - you mentioned writing an essay on this topic recently; would you mind sharing what you discussed? (You're welcome to PM me if you'd like.)

[Skidoo]

[ QUOTE ]
But then I don't see any need to rationalize the two, since if the universe is deterministic, there's no reason I can think of why it couldn't exist in such a way as to fool me into thinking I have free will even though I don't actually have it.

[/ QUOTE ]

Not that either of us is right or wrong here, but this is the second seemingly incomprehensible concept you've introduced in this thread (in fact, it's probably a good thing).

First was your suggestion that non-determinacy is an improvement over pre-determinacy as a basis for self-determinacy. This was more of a question by you than an assertion, so I'm not calling on you to prove it or anything.

Now it's this notion of the illusion of free will. How is this even possible, in your opinion? If you attempt to exercise what you think is free will and then you exercise it, it's free will. In other words, how can unfree will exist?

[arahant]

Free will is definitely not taken as a given by most modern, intelligent people. The compatiblists are just kind of reaching...

In response to your original question:
Does it actually matter whether the universe is deterministic or not? If you have some kind of quantum switch in your head that results in your decisions being 'truly' random, does this constitute free will? It's important to note that the indeterminacy of quantum physics (in interpretations that posit indeterminism) is not a question of ignorance, but of genuine randomness. There is no underlying mechanism that WE can't predict, the mechanism is simply unpredictable by nature.

Further, quantum effects aren't really relevant for the human brain. Even assuming that your choices WERE somehow randomized as a result of quantum indeterminacy, your perception of how you arrived at those choices (i.e., your illusion of free will) would be no different than if they were 'deterministic'.