[excursionist]

I don't see how any kind of scientific experiment could possibly support the concept of free will. If the universe is deterministic, then obviously there is no free will - since humans are part of the universe. If it is non-deterministic then all we can say about events we identify as non-deterministic is that we don't understand them.

[chr1]

This is not obvious at all, even with deterministic and computable universe there is a good analog of free will.

The first thing that is needed or this to work, is for the part of universe representing the human to be separable from the rest of the universe (this is not true with superdeterminism, which requires choices that experimenters make to be correlated with the quantum states of particles they are studying, but then almost no one takes superdeterminism seriously).

This separability would allow to talk about choice, as it allows to modify or swap the human in question and recompute the future in the same universe where the human may make another choice.

The second thing is the conjecture of computational irreducibility: that is for sufficiently complex systems like humans and for sufficiently long timeframes, the only way to predict future state is to evaluate the system. This conjecture seems plausible because even cellular automata in chaotic state, do not appear to have any simplified method of evaluation

If this is true, you may be able to easily predict some of the choices human will make based on his state several seconds before that, but for longer time intervals the only way is to let the human live and make the choice (even if it lives in your computer simulation).

[NOGDP]

> The first thing that is needed or this to work, is for the part of universe representing the human to be separable from the rest of the universe

What do you mean by 'separable'? Humans are a product and part of the universe.

> This separability would allow to talk about choice, as it allows to modify or swap the human in question and recompute the future in the same universe where the human may make another choice.

I'm not sure what this shows. If you swap the human for a different one then you would expect a different choice. If you can't 'recompute' the exact same universe with the exact same human, that also doesn't show anything other than your inability to recompute.

> If this is true, you may be able to easily predict some of the choices human will make based on his state several seconds before that, but for longer time intervals the only way is to let the human live and make the choice (even if it lives in your computer simulation).

The fact that we can't perfectly predict what a human will do doesn't mean there is free will. It just means we don't understand the system enough.

[chr1]

If universe is deterministic and computable, then it is possible to create a simulation of a part of the universe that would be complex enough to contain humans and would be simple enough to pause computation, make changes to the state, copy the state, etc. So for simplicity i will talk about this simulated universe.

Separable here roughly means that to compute further states of a human you need to follow only particles in that human and not deal with variables describing the whole universe.

You can recompute exact same universe with exact same human, but it will give you the same result. Recomputing with different human shows that different choice was possible in principle.

In the simulation we can perfectly predict what the human will do, but if computational irreducibility conjecture is true there is only one algorithm to make that prediction, which is running the simulation itself. And because running the simulation is equivalent to letting the simulated human to live that means we do not predict, but merely observe the choice.

This is not exactly what everyone thinks when talking about free will, but this is a close enough equivalent that can exist in a computable universe, because multiple choices are available, and the choice is made by the part of the universe representing the human.

[NOGDP]

> If universe is deterministic and computable, then it is possible to create a simulation of a part of the universe that would be complex enough to contain humans and would be simple enough to pause computation, make changes to the state, copy the state, etc. So for simplicity i will talk about this simulated universe.

I don't see how the 'computable' part is relevant in regards to free will. You can write a program that outputs random numbers that it reads from some source, and you can simulate it by writing another program that outputs random numbers from the same source. The two equivalent programs will generate different numbers, but that doesn't mean they had any choice over the numbers they printed.

> Recomputing with different human shows that different choice was possible in principle.

Recomputing with different human is equivalent to creating an impossible universe. It's impossible to have two different people in the exact same situation at the same point in time in the same deterministic universe. The very action of pausing or modifying the universe from without would make the universe non-deterministic.

> And because running the simulation is equivalent to letting the simulated human to live that means we do not predict, but merely observe the choice.

Who's choice? If the algorithm is making the choice then the humans simulated by such an algorithm would not have any more free will than a video game NPC.

[chr1]

Using random numbers affects the condition about determinism not computability. If universe is not deterministic then the choice made does not depend only on the human making choice but also on the state of generator that creates random numbers. Of course even here it is possible that the state of human is organized in such a way to change probability distribution to not depend on randomness, but that becomes equivalent to deterministic universe with additional complications.

The computability is relevant to the argument because it allows us to create simulation, and to observe a universe from outside. If it was not computable, say required real numbers with infinite precision, and the finite approximations were not able to describe complex things such as humans, then we would not be able to complete our thought experiment.

> The very action of pausing or modifying the universe from without would make the universe non-deterministic.

There are two parts, the starting state and the evolution rule. Here the evolution rule is still deterministic, and the requirement is for it to be able to continue from different starting states.

> Who's choice? If the algorithm is making the choice then the humans simulated by such an algorithm would not have any more free will than a video game NPC.

If human is a part of universe, and does not have a soul, then he is equivalent to its starting state plus the algorithm. If the computation cannot be reduced to a simpler algorithm then no matter how you compute the future state you get that human thinking, feeling and making a choice. The difference with game NPC is that the algorithm doesn't have a hardcoded set of inputs and outcomes but can accept any inputs and produce outcomes that can't be predicted by anything other than that algorithm with that starting state.

[NOGDP]

> If the computation cannot be reduced to a simpler algorithm then no matter how you compute the future state you get that human thinking, feeling and making a choice.

What's the difference between the human thinking, feeling, making a choice and a trained neural network making a 'choice'? I would not say a neural network has free will.

> The difference with game NPC is that the algorithm doesn't have a hardcoded set of inputs and outcomes but can accept any inputs and produce outcomes that can't be predicted by anything other than that algorithm with that starting state.

You can have a program that could accept any inputs (say any binary sequence) and produce output based on that.

I think that if the universe is deterministic and computable then that implies no free will, since humans are part of the universe and therefore also deterministic and computable.

[codeulike]

Or, its deterministic, but so complex that its literally impossible to exploit the determinism to 'look ahead' in any way ... you'd need to simulate every subatomic particle, therefore needing something bigger than the universe to 'look ahead'. So perhaps the universe is like a deterministic computer that is calculating its own future. The determinism in that case just doesn't really mean anything - it can't be repeated, it can't be predicted or exploited. And so the whole problem goes away.

[pedrocr]

How does the problem go away? If you can prove your thesis then even though you can't exploit the determinism you've proven that you can't influence the future. Doesn't that mean that free will doesn't exit and is thus an extremely important result?

[codeulike]

The future is unknowable and you're part of the mechanism that is unfolding it microsecond by microsecond. The question of whether or not you can 'influence' it doesn't make any sense.

That is, Free Will as a concept doesn't really make any sense. Does Free Will mean if exactly the same situation happened twice, the person might choose different things? But its somehow different to just being random? And when does exactly the same situation every happen twice anyway? Its an incoherent concept.

In my head, I have sortof redefined 'free will' like this:

The world is a mass of cause-and-effect chains. For a given object/being, if you were to 'trace' those cause-and-effect chains, would most of the proximate links in the chain be within the object/being, or outside of it? e.g. a rock can fall and roll around if pushed, those chains of cause-and-effect are mostly outside it. Us, as humans, choose to do things using our brains, so the chains of cause-and-effect (or the first bits of the chain at least) are within our brains. Naturally if you trace the cause-and-effect far enough you will get to some external cause (memories of previous events, learning etc). But if you look at the proximate cause-and-effect chains, they're mostly in our brains. That - for me - is roughly what I take Free Will to mean. The center-of-gravity of recent cause-and-effect chains reside within us. We have it, most animals have it to varying degrees. Rocks dont have it.

[chr1]

There is also the case of several simulations of a smaller universe running in our universe, with the external observer trying to look ahead.

But even if you could simulate the universe to look ahead, most likely there is only one possible algorithm of simulation, so looking ahead is still equivalent for the tested subject living and making its choice.

So even if it can be repeated, the simulation is more like a time machine than a formula.

[excursionist]

It's possible to predict local events with a certain degree of accuracy. The better our models/knowledge and computational capacity the greater the accuracy. We can see patterns on a macro level and exploit them without looking at electrons.

[codeulike]

Sure yep, thats like the whole of science. But we can't predict things at the level that people worrying about Free Will worry about. i.e. what people are going to do next. Or what they will be doing in 15 years time. Or going further, the nightmre of determinism is the idea that someones whole life is determined before they are born and so on. That sort of thing is forever beyond the reach of all computation.