A technical question about free will

[Metric]

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The upshot of all this is that it seems to me that the universe probably isn't deterministic, and my understanding of quantum physics (such as it is) also seems to support the notion of a non-deterministic universe. (Which is why I asked my question; basically I want to back-check whether or not Q.P. actually does support a view of the universe as non-deterministic.)

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The way quantum physics balances determinism and probability is extremely subtle. Extremely subtle. Only now is a really good understanding of this emerging, in the context of quantum information theory. One way to describe the situation is this: the full quantum state of the universe evolves in a completely deterministic way -- however, the information obtained by one quantum subsystem (an observer) about another quantum subsystem (say, an atom), is inherently probabilistic. This may seem contradictory on the surface, and indeed the entire 20th century had to pass before people really began to nail this concept down.

[madnak]

Being brief.

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if all of my actions could be predicted with absolute certainty before I was born, I cannot have true free will

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What is "true free will?"

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obviously I have the perception that I have free will,

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That's not obvious to me. Can you explain why it should be?

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in the sense that even though I'm typing this sentence right now, it sure *feels* like I could stop, if I wanted to

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If you wanted to stop, then there would exist a cause for your stopping (the desire to stop typing). The statement "if" here represents a causal contingency - how is this consistent with your presentation of free will (which you have described as being the opposite of causal contingency)?

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I think it matters a great deal, yes. It seems to me that a universe that is completely deterministic, that is, whose future interactions are all perfectly predictable given some present set of knowledge, would automatically preclude free will, since free will implies the ability to make choices that potentially affect outcomes. (Thus, if the outcome is already known, then my "choices" that lead to it must also be known, and therefore are in some sense, "immutable in advance", and thus aren't really choices at all. Instead they would have to be, in some form, mere consequences of the laws of the universe.)

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This isn't a valid argument, and it doesn't work as an appeal to my intuition (partly because I think the intuition of "free will" is essentially a western cultural construct in the first place, partly because appeals to emotion just aren't valid rationally, and partly because I have no such intuition and so the example fails to resonate and seems like nonsense to me).

The outcome can only be predicted if you can fully identify and calculate the effects of every event preceding it, including your choices. Thus, your statement amounts to "if I know for a fact what I'm going to choose, then I can't choose otherwise." While tautologically true, this statement is completely circular and has no apparent relevance to determinism, free will, or physics.

[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'.

[jogger08152]

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In response to your original question:
Does it actually matter whether the universe is deterministic or not?

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I think it matters a great deal, yes. It seems to me that a universe that is completely deterministic, that is, whose future interactions are all perfectly predictable given some present set of knowledge, would automatically preclude free will, since free will implies the ability to make choices that potentially affect outcomes. (Thus, if the outcome is already known, then my "choices" that lead to it must also be known, and therefore are in some sense, "immutable in advance", and thus aren't really choices at all. Instead they would have to be, in some form, mere consequences of the laws of the universe.)


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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.

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To the extent that quantum physics tells us that our universe - and therefore, our choices - are not predictable in this way, it increases the likelihood of free will. It does not necessarily, and need not, constitute it. (Of course, maybe it does something else that I'm not aware of or not thinking of, that would also preclude free will. But absent this, quantum physics as I understand it (note though, that my understanding is second hand, at best that of a decently bright lay person without the scientific skills necessary to verify the explanations/summaries I've run across) does seem consistent with my perception that I have free will.)

Best regards,
Jogger

[Sephus]

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To the extent that quantum physics tells us that our universe - and therefore, our choices - are not predictable in this way, it increases the likelihood of free will.

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if they're predictable according to probability distributions instead, it doesn't seem to make free will any more likely.

[Brom]

Here's a quote from a Wiki article that pretty much sums up what I thought on the compatability of quantum physics with determinism;

"So quantum mechanics is deterministic, provided that one accepts the wave function itself as reality (rather than as probability of classical coordinates). Since we have no practical way of knowing the exact magnitudes, and especially the phases, in a full quantum mechanical description of the causes of an observable event, this turns out to be philosophically similar to the "hidden variable" doctrine."

Link

[Piers]

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

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not speak to.

I think to understand free will it is best to consider the brain as an organic computer. Somewhere between the biochemical level (Hardware) and the discharge of thoughts moving through the brain (software) it should eventually be possible to isolate the patterns that generate the sensation of free will.

Quantum physics is at a completely different level. Might as well use quantum physics to determine how long to microwave a frozen pizza.

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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.

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This does not necessarily follow. And not only because its neither possible to know the state of all things nor have enough computing power. And it has nothing to do with the sensation of free will, which a consequence of certain biochemical processes in the brain.

[Skidoo]

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Might as well use quantum physics to determine how long to microwave a frozen pizza.

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Quite right. And besides, I would question how this notion of accounting for free will with incompleteness ever got started. A system not having a unique state does not give it the ability to choose its state. That's apples and oranges.