Why so many want, or are not disturbed by, a "deterministic" universe?

[HomesliceMMA]

Determinism, as I understand it, means that everything that can ever happen could, has already been determined, because everything is just a reaction based on everything else. With good enough instruments you could predict with 100% accuracy the future of everything in the universe. Quantum mechanics, as I understand it, truly has a random element to it, so seems inconsistent with determinism.

I am curious, why do so many people want a universe to be deterministic? Or at least, are OK with a deterministic universe? The thought seems absolutely appalling to me - if everything is just a reaction to other things, then an argument for a determinative universe is necessarily not based on logic and reason, but instead its just what the chemicals in your brain are telling you to do, and that was your destiny. No arguments, points, logic, etc. is "real" in the sense that if it happens to be correct its not because if its inherent correctness, but just luck of the draw that the chemicals in your brain told you to make that argument/point/logical deduction, etc.

I don't see how a deterministic universe is not appalling to everyone...

 

[PeroK]

Determinism, as I understand it, means that everything that can ever happen could, has already been determined, because everything is just a reaction based on everything else.

That's about it.

With good enough instruments you could predict with 100% accuracy the future of everything in the universe.

That doesn't follow. At the very least the instruments are part of the universe and you can not [edit] (even theoretically) measure everything to unlimited accuracy.

Quantum mechanics, as I understand it, truly has a random element to it, so seems inconsistent with determinism.

Correct, although some might argue with that.

I am curious, why do so many people want a universe to be deterministic?

Good question. Human frailty, IMO.

Or at least, are OK with a deterministic universe? The thought seems absolutely appalling to me

It doesn't make any practical difference. The universe is FAPP probabilistic, regardless of whether the underlying laws of physics are deterministic or not.

 

[Frabjous]

Non-deterministic does not mean free will exists. So it is really just a different set of aesthetics.

 

[HomesliceMMA]

With good enough instruments you could predict with 100% accuracy the future of everything in the universe.

That doesn't follow. At the very least the instruments are part of the universe and you can (even theoretically) measure everything to unlimited accuracy.Thanks PetroK! On the one above, are you saying that in a deterministic universe you CANNOT measure everything to unlimited accuracy? I think maybe you were just typing quick and left out the "not" part. So, if I am right, in a deterministic universe, everything that will happen is known from the inception if one were to know the initial conditions, its just that measure same to 100% accuracy would be impossible? Why impossible? I don't mean like the uncertainty principle, like not real limitations that might be in our universe, I just mean theoretical limitations in a deterministic universe.

It doesn't make any practical difference. The universe is FAPP probabilistic, regardless of whether the underlying laws of physics are deterministic or not.

Probabilistic means like based on probabilities at the quantum level like in quantum mechanics, correct? I'm OK with probabilistic as long as it is not deterministic, its deterministic that is the bridge too far IMO for the reasons I stated.

Thanks!

 

[HomesliceMMA]

Non-deterministic does not mean free will exists. So it is really just a different set of aesthetics.

I would say that is correct - non-deterministic does not necessarily mean free will exists, but it certainly allows that possibility. Deterministic (as I understand it) does not allow that possibility. So if this were a deterministic universe we would necessarily not be using logic address the points we are addressing here, or any other points described on this forum, any other forum, or by anyone ever - there is no such thing as logic and reason, all that goes out the window because "the [chemicals] made [them][us] do it".

 

[PeroK]

On the one above, are you saying that in a deterministic universe you CANNOT measure everything to unlimited accuracy? I think maybe you were just typing quick and left out the "not" part.

Yes, corrected.

So, if I am right, in a deterministic universe, everything that will happen is known from the inception if one were to know the initial conditions, its just that measure same to 100% accuracy would be impossible? Why impossible? I don't mean like the uncertainty principle, like not real limitations that might be in our universe, I just mean theoretical limitations in a deterministic universe.

1) You can only measure something to a finite accuracy. This gives you only almost perfect predictions for a limited time. Not indefinitely. And, complex systems can be very sensitive to initial conditions.

2) Even without QM there are too many atoms to measure the position and momentem of them all. E.g. every molecule in the Earth, or the whole solar system. That's impossible even if you fill the solar system with as many measuring devices as possible.

3) Systems may generally be chaotic, even if they are governed by simple mathematical equations.

In short, deterministic doesn't mean indefinitely predictable. These are different concepts.

 

[Frabjous]

non-deterministic does not necessarily mean free will exists, but it certainly allows that possibility.

I am not sure I believe that.

 

[HomesliceMMA]

Thanks PeroK! I think I follow you. Taking your last statement:

"In short, deterministic doesn't mean indefinitely predictable. These are different concepts."

Got it, and I think I understand. But deterministic would mean there is no free will, would you agree with that? And more broadly, in a deterministic universe, when one thinks they are using logic or reason, they are not, those thoughts of theirs had to occur?

 

[HomesliceMMA]

I am not sure I believe that.

But see, it is my view that if you don't think you have free will, you saying you are not sure you believe that is in fact not based on logic or reason - you were determined to say that at the beginning of the universe. Indeed, nothing you ever said, did, or thought was based on logic or reason, it was all determined from the inception. Its like a paradox, at least of sorts - you are saying, based on logic, you don't believe their can be free will, but if there is no free will you could not have used logic to get to that conclusion. Your "logic" would just be "I said it because I had to say it, and what I say next I will say because had to say it".

 

[Frabjous]

But see, it is my view that if you don't think you have free will, you saying you are not sure you believe that is in fact not based on logic or reason - you were determined to say that at the beginning of the universe. Indeed, nothing you ever said, did, or thought was based on logic or reason, it was all determined from the inception. Its like a paradox, at least of sorts - you are saying, based on logic, you don't believe their can be free will, but if there is no free will you could not have used logic to get to that conclusion. Your "logic" would just be "I said it because I had to say it, and what I say next I will say because had to say it".

That there was a 95% chance I would say one thing and a 5% chance that I would say another does not mean I had any say in the choice.

 

[PeterDonis]

I am curious, why do so many people want a universe to be deterministic?

This is not a question about physics, it's a question about people's feelings and opinions. As such, it is off topic in this forum. So are discussions of free will vs. determinism, since such questions are not questions about physics.

Thread closed.