One way is to show that, given a state of the universe, it is possible to determine the next state. From what I understand, this does not seem to be the case.
I think free will vs deterministic physics is a false dichotomy.
My instinct is that physics is performing a computation at optimal efficiency. Even if everything is deterministic, there is no other way to determine the outcome other than letting it play out.
In other words, even if a decision you made was bound to happen, there was no other way to find out what that decision would be beside letting you compute it.
So, your decisions can be both deterministic and unpredictable.
From this perspective, I don't think the existence or absence of randomness makes any difference on the question of free will.
Lets assume determinism is epistemological unfeasible, ie not possible to evaluate all the states due to limitations. Unpredictability makes no difference to the ontological question of whether actions are due to casual chain or pure irreducible randomness (if it exists in fundamental level). There is no other alternative. Free will is ill defined/semantic nonsense in libertarian sense of its use as there are only two possibilities.
Is this a strictly hypothetical thought experment-type of design? Ie, nothing that could be realistically built and tested? I am asking because our current understanding of physicas is that it is practically impossible to know exactlt the state of even a single particle, let alone of the whole universe, to the precision even theoretically required to "determine" the next state. (Outside of simplistic esperiments in a laboratory.)
This is not a limitation of technical prowess, this is a quality of quantum particles, of thermodynamics, etc.
My point is, if it is impossible to construct such an experiment, it means it is not a question within the domain of science. Science deals with hypothesis which can be realistically disproven.
>From what I understand, this does not seem to be the case.
Maybe. Determinism isn't dead, by any means. Depending on what model of quantum mechanics turns out to actually be correct, full determinism might be just fine. But even if one of the models that would invalidate full on determinism is correct, 'adequate determinism', similar to what Stephen Hawking believed in, might apply - the idea that the level any quantum fluctuations occur at makes it unlikely to result in any difference at the level that human thought, etc., operates at.
Exactly, which makes "free will" a semantic nonsense term. Understanding that neither determinism nor in-determinism of the universe show anything about popular conception of free will (libertarian sense) allows one to exit a semantic misconception.
If determinism is correct, then given enough storage and computational power (or intelligence capable of doing this within their mind), an outside observer would be able to figure out every single action I would ever take before I took it.
If how my brain works is deterministic, and all of my encounters are able to be pre-determined, and those all deterministically shape my decisions and actions, then... how I can I possess libertarian free will?
I think it can't be the case because the brain is a chaotic system. But hiding behind chaotic behavior to preserve "free will" is farcical, isn't it? We can't know how the pendulum[0] will swing next, so we can say that it's got free will?
Well, chaos theory is explicitly not a denial of determinism, and speaks more to our ability to precisely measure state and accurately model it than anything else. The more precisely you can can measure state, the longer the Lyapunov time, and the longer we can accurately predict the future states of the system.
There are systems today that we can predict fully (i.e. we can predict what will happen faster than it can actually happen) that decades ago would have been unpredictable due to their chaotic nature. There are systems we cannot predict today that we will be able to in the future. Brains very well could be one of them.
It's not "farcical". If you could prove that physical states are deterministic, you could prove that there is no free will. That statement makes no claims whatsoever about what it means that physical states are not known to be deterministic. In other words, it could have been useful as proof negative of free will, but not as proof positive. And that's okay.
Wheter "free will" exists or not seems like a technicality, tied to whether the Universe is deterministic or not. Whether or not it's deterministic, a brain must still go through its thought processes to come up with any decision. The only difference that non-determinism makes is that the decision may randomly go one way or the other based on low-level fluctuations. Thinking and decision making still occurs even if the Universe is deterministic.
To be clear, I think that free will--by definition--cannot exist in a purely deterministic universe. Any semblance of free will in such a universe would be purely illusory. It also cannot exist in a universe where events can only ever be some combination of random events and determined events. Randomness is also not free will.
Free Will would have to be some other special category of events that is neither determined not random. We don't have a word or phrase to describe what these events would be like other than "Free Will." However, lacking the vocabulary and math to describe it does not make it non-existent.
>Free Will would have to be some other special category of events that is neither determined not random. We don't have a word or phrase to describe what these events would be like other than "Free Will." However, lacking the vocabulary and math to describe it does not make it non-existent.
That is not even non-existent, more like a misconception which one comes out of by thoroughly examining what "feels" correct. Like Wittgenstein said one of the jobs of philosophy is to free us out of semantic knots. I see free will such a knot arising due to our conception of a separate self from the causality, leading us to project a conception of freedom which makes no sense when examined upon.
I think this is some kind of supernatural "free will", and no mechanism has been found for such a thing in science. It's associated with mind–body duality, souls, homunculi inside the body, that kind of thing.
It doesn't have to be super natural either, though. By the nature of it's existence, the universe proves that there can be chains of events spawned that completely undermine our current treatment of causality. A realistic model must include at least one of the following:
1) Events with no cause such as the beginning of the universe or broader multiverse, depending on your beliefs or 2) Infinite regressions of causal chains if you believe that the universe or God (or a god) has always existed or
3) Some combination of the above.
In all of these, somehow there can be uncaused effects, but in 1) and 3) some causal chains can just begin existing, like free will would require.
My instinct is that physics is performing a computation at optimal efficiency. Even if everything is deterministic, there is no other way to determine the outcome other than letting it play out.
In other words, even if a decision you made was bound to happen, there was no other way to find out what that decision would be beside letting you compute it.
So, your decisions can be both deterministic and unpredictable.
From this perspective, I don't think the existence or absence of randomness makes any difference on the question of free will.