All absudities we can come up with rely for their absurdity on the contrast with the real world as we experience it. But if that world is not actually deterministic then of course a non-deterministic world looks exactly like our world. — Echarmion

Can you explain this in more detail? Why would a non-deterministic world appear like ours? Why would a non-deterministic world "appear" at all? You possess genes passed down faithfully over thousands of generations through sexual acts repeated over thousands of generations. That's not happening in a universe without that deterministic regularity. There's no reason to expect the same act to achieve the same thing billions of times over, the same useful gene to be replicated billions of times over.

But who are we asking? Ourselves. Are we an unbiased observer? There doesn't seem to be a reason to think that our brains are somehow designed to answer the question. — Echarmion

Almost certainly our brains are evolved to identify deterministic behaviour. And the overwhelmingly likely explanation for that given natural selection is that it is useful. Identifying causality in a non-deterministic world doesn't seem useful. There would be no benefit in a frog being able to predict where the fly will be in 0.5 seconds such that it can flick out its tongue in the right direction if the fly's trajectory is random. Therefore such a characteristic would not evolve. We are inclined towards determinism because the universe seems deterministic, not the other way around.

Certainly it would prove it incorrect in this instance. For example some cheating could well be at play.

These criteria seem to come from nowhere and go nowhere. I didn't ask about any of that. I asked you to imagine an experiment that could disprove determinism. And you have failed to do so. — Olivier5

And, as I keep saying, you don't to devise a particular experiment. Any experiment that fulfils those criteria would suffice. The important thing would be the measurement that is inconsistent with the presumption of determinism.

Any experiment that fulfils those criteria would suffice — Kenosha Kid

Your criteria are Chinese to me. Give me one example of an experiment that could disprove determinism. The question is very simple.

For example some cheating could well be at play. — Olivier5

Through gritted teeth... all relevant information

Through gritted teeth... all relevant information — Kenosha Kid

You are not God, are you?

Certainly it would prove it incorrect in this instance. — Olivier5

Okay, so then if you take a radioactive material, where there are a few mol of atoms decaying, you can be sure there is something going wrong if hitting that 2^-100 probability in finding a non-decayed atom?

You are not God, are you? — Olivier5

If the relevant information required omniscience, it would not be a good test for determinism. Gimme a holler when you acquire the ability to retain information.

Probabilistic theories are in practice discarded when their odds of being wrong is repeatedly calculated at more than 10%. Some place the bar at 5%. It's subjective. To simplify it means that in a casino, a player who beats the odds repeatedly by more than 10% should be looked at very closely, cause something is askew in his stats.

You are a bit slow realizing the problem... Omniscience is required to test determinism. One has to know the true laws of nature in order to know if they are determinist of not. There's no other way. Otherwise you're only testing an hypothethis, which you can reject if the experience fails, without rejecting determinism. Another determinist hypothesis may still work. Maybe you just tested the wrong theory.

That is why you are incapable of thinking of an experiment disproving determinism. It's not your fault; it cannot be done.

What is your fault, really, is your hubris, your way of thinking as if you were God, to assume you can know all relevant information about a certain situation, for instance. This is ridiculous, sorry to say, and not worth my time. How the heck would you know that you know all relevant information, pray tell? You have an all-relevant-information meter hidden somewhere that we should know about?

Can you explain this in more detail? Why would a non-deterministic world appear like ours? Why would a non-deterministic world "appear" at all? — Kenosha Kid

Why would random fluctuations in the wave function collapse into precisely the effects we experience as classical mechanics? Prima facie, the way the universe actually appears to work is absurd, at least to our everyday notions. Until the second half of the 20th century, the assumption behind determinism was that the universe was an actual, mechanical mechanism. But we haven't found the cogs and wheels, indeed what we did find is completely strange. And we still haven't figured out how it all fits together. Doesn't that show that what appears to be a determined, "mechanical" apparatus can turn out to be anything but?

We just know that it's sufficiently predictable to get cars, planes and microscopic electronics. That proves that the universe isn't so random as to prevent these kinds of predictions. And yet everyone one of us can easily set up an experiment where the outcome is dependant on a random quantum fluctuation, and according to our current understanding, there is no way to predict that exact outcome.

We are inclined towards determinism because the universe seems deterministic, not the other way around. — Kenosha Kid

How would we know the difference though? This kind of evolutionary argument always presupposes that the end result is in fact selected for. But we know that not every attribute of every organism is actually selected for. Some are random in an evolutionary sense, i.e. they aren't actually the result of any selection pressure.

It's the same with determinism more generally. We assume "the" universe is deterministic because we can make all these predictions. But what this fails to recognise is that the predictions are our universe. There aren't two universes, the "real" and the "model" in our mind. Whatever "the" objective universe may be, the universe in our mind is a collection of predictions. We don't check these against an objective reference point somewhere. It's only when new information does not fit the pattern at all that we re-evaluate and then only to find a new solution that is "good enough". Maybe the result is something that looks like the "real" universe. But maybe it's a weird jury rig, like so many of the results of evolution are.

To simplify it means that in a casino, a player who beats the odds repeatedly by more than 10% should be looked at very closely, cause something is askew in his stats. — Olivier5

Thats trivial. Just as trivial as that there is no proof of anything. The casino can get him out without having to justify it. Just as there is no objective criterion to dismiss a theory. I remember a cite from Popper stating that one could know how things are not. In statistics this is not the case. In this sense Popper was outdated by theories that do not care about truth but about usefulness or buisiness values.

One has to know the true laws of nature in order to know if they are determinist of not. — Olivier5

Again, not relevant. Newton's laws are sufficient to wang a probe around the solar system for a few decades and land it in your back garden. Tackling this with GR would again be intractable. But even more broadly, Galileo was able to make perfectly good predictions about balls rolling down inclined planes without knowledge of general relativity, or whatever true law GR is an approximation to.

Otherwise you're only testing an hypothethis, which you can reject if the experience fail, without rejecting determinism. Because another determinist hypothesis may still work. — Olivier5

Yes, that's true. I could write down a mathematical formula that describes how a ball released from a box will accelerate upward into the sky at 9.8 m/s/s then find that my theory is wrong. But, as I've already explained, that is irrelevant. What would be relevant is if I released the ball and sometimes it stayed still, sometimes it flew upward, sometimes it disappeared completely, sometimes it quoted Shakespeare. If that happened, with all relevant information about the ball available to me and no conditions in the setup that made me either predict those outcomes deterministically or lead me to believe I could not make a prediction that would discern deterministic from non-deterministic behaviour -- and no such possibilities spring to mind -- I would not expect a new deterministic theory to explain it and would likely consider determinism well and truly falsified.

The tractability of a problem is relevant insofar as I can have some expectation of what outcomes would be considered consistent or inconsistent with determinism. For instance, the Schrödinger's cat thought experiment is intractable because I cannot solve the time-dependent many-body wavefunction of a radioactive isotope, radioactivity detector, hammer, glass vial of poison gas, cat and box. I can have no real expectations of an outcome, and no means of establishing whether repeated experiments are at all comparable.

Irrespective of the particular theory of gravity, I do have the means to compare what happens to a ball released from a box. It is a tractable problem. What the final state of the ball is is not important. The phenomenon could be completely non-deterministic and still consistent with a deterministic theory if I only check once. What is deterministic is being able to repeat the same experiment under the same conditions (to whatever precision is relevant) and expect the same result.

You are doing this already btw. Whenever I hear this sort of thing I can't not chuckle, because there you sit, hitting keys on your keyboard with utmost expectation and surety that when you hit the key T a T (or t, as you select) will appear on your screen in the expected place and when you hit send it will with complete fidelity appear on everyone else's screen precisely where you intended, as you explain to us that the universe is not deterministic. I would wager that, were it a R in place of a T, you would blame yourself for a typo rather than blame the complex infrastructure we have for its lack of fidelity or the Universe for its lack of determinism. Your sheer persistence in arguing for a non-deterministic world is a testament to how deterministic you really know the world to be. And there's quantum mechanics involved in that process between you hitting a key and me reading your T to boot.

So... Did you find that magical experiment yet?

So... Did you find that magical experiment yet? — Olivier5

I found that no amount of explanation is going to demonstrate how that question demonstrates zero understanding.

I'll take that as a no.

I'll take that as a no. — Olivier5

Do as you please, but don't expect kudos for it.

You just proved that determinism is a metaphysical theory, because there is no conceivable experiment with a conceivable outcome that could prove it false. Even if balls spake in Shakespearean verses, we would still be looking for what could possibly cause that, rather than just conclude "oh well, the universe is acting funny tonight".

I expect you to understand it at some point, but perhaps not today.

Why would random fluctuations in the wave function — Echarmion

There are no random fluctuations in the wavefunction. In even the probabilistic interpretations of QM the wavefunction evolves deterministically under a wave equation until measurement.

Prima facie, the way the universe actually appears to work is absurd, at least to our everyday notions. — Echarmion

Well QM is certainly absurd according to everyday notions, whether it proves deterministic or not.

Doesn't that show that what appears to be a determined, "mechanical" apparatus can turn out to be anything but? — Echarmion

Definitely. I'm not arguing for a deterministic view of QM though. Whether QM is Copenhagen-like or MWI-like is not within our grasp atm. I'll go where the evidence goes. But by the same token, it can't be used as proof that the universe is macroscopically or microscopically non-deterministic.

That proves that the universe isn't so random as to prevent these kinds of predictions — Echarmion

Or indeed any kind of prediction at the moment. It is unfortunate and perhaps not uncoincidental that the realm of physics where determinism is in doubt is the one where we cannot make predictions. We can't solve the equations even crudely for measurement apparatus. That's a huge problem.

But what you're talking about here is Popper's indeterminacy of the gaps. This presumably fundamental randomness of the universe is weirdly constrained to whatever our peak technological capability ends up being.

But we know that not every attribute of every organism is actually selected for. — Echarmion

Such as? There's the supposed junk DNA, but they are not physical characteristics that can be provided for. If there is a characteristic that benefits us, there has to be an environment in which that benefit can be exploited. Or God, I suppose. Something, anyway, that persists useful characteristics from generation to generation for hundreds of thousands of years, despite evolution apparently being purely random. ???

We don't check these against an objective reference point somewhere. It's only when new information does not fit the pattern at all that we re-evaluate and then only to find a new solution that is "good enough". — Echarmion

Very true, science is not divine revelation. But we do have consensus. A non-deterministic theory of nature not only had to explain why you experience the same phenomena under identical circumstances, but why everyone else does so too. So far, no one has reported that a ball on an inclined plane had a 50/50 chance of rolling up.

In this sense Popper was outdated by theories that do not care about truth but about usefulness or buisiness values. — Heiko

That may well be the case. But people who do not care about truth don't usually succeed very long. Everything is that trivial in the end: it's about probabilities, always. There is no full certainty about much. All we know in biology is based on stats for instance. And yet it works. We're learning useful stuff.

But people who do not care about truth don't usually succeed very long. — Olivier5

People... usually know that everything has it's place. This is why there is not too much arguing about maths being a "sure" basis for empirical science. Even if the content can only be described via probabilities it is simply not true that

Everything is that trivial in the end: it's about probabilities, always. There is no full certainty about much. — Olivier5

you'd either have to say there is no certainty about nothing or consider metaphysics.
Schroedinger's cat may well know if it is alive or not.

you'd either have to say there is no certainty about nothing or consider metaphysics. — Heiko

I do consider metaphysics, I don't discard them. Every body got some metaphysics or another. Mine is that the universe is open, evolutive, not predetermined, and thus that time is not redundant, and that we can be free.

There are no random fluctuations in the wavefunction. In even the probabilistic interpretations of QM the wavefunction evolves deterministically under a wave equation until measurement. — Kenosha Kid

Right, I tend to mix this up. What I was getting at is that classical mechanics arise from events that are not mechanical, and not determined in the way that interactions are in classical mechanics.

This isn't proof that the universe is non-deterministic. I have already pointed out that I am not trying to prove the nature of the universe to you. What I am saying is that the experience with classical mechanics should be a cautionary tale for everyone who assumes the universe must be deterministic based on everyday phenomena.

But what you're talking about here is Popper's indeterminacy of the gaps. This presumably fundamental randomness of the universe is weirdly constrained to whatever our peak technological capability ends up being. — Kenosha Kid

Isn't that essentially Einstein's argument of the hidden mechanics? There is no evidence, right now, that the uncertainty can be resolved.

Such as? — Kenosha Kid

Lots of organs are weird and inefficient. The human eyeball is a common example, as are various vestigial limbs found in species.

But we do have consensus. A non-deterministic theory of nature not only had to explain why you experience the same phenomena under identical circumstances, but why everyone else does so too. So far, no one has reported that a ball on an inclined plane had a 50/50 chance of rolling up. — Kenosha Kid

We already have a theory that explains how lots of individually non determined events combine into sufficiently deterministic phenomena. Interference patterns. Again this isn't "proof". I obviously have no idea how the universe " really" works.

Isn't that essentially Einstein's argument of the hidden mechanics? There is no evidence, right now, that the uncertainty can be resolved. — Echarmion

What I mean is that as we measure, say, the spin of a neutron to ever greater precision, the degree of freedom of non-determinism to show its face gets ever smaller.

Lots of organs are weird and inefficient. The human eyeball is a common example, as are various vestigial limbs found in species. — Echarmion

Ah, but that doesn't mean they weren't selected for. We have an appendix that is useless to us, but we are descended from grass eaters.

Again this isn't "proof". I obviously have no idea how the universe " really" works. — Echarmion

It can't be proven. My point was just that you have an extremely simple explanation for consensus -- determinism -- or a really complicated and dubious one.

complicated and dubious one — Kenosha Kid

It's not complicated to abandon an hypothesis, especially when it makes no pragmatic difference whatsoever.

It's not complicated to abandon an hypothesis, especially when it makes no pragmatic difference whatsoever. — Olivier5

Can I ask... Is English your first language?

No, I'm French.

No, I'm French. — Olivier5

Okay cool. Sorry, it's come across several times like you're willfully misunderstanding everything. Obviously there's a slight language barrier and I should have considered that. My bad.

Modesty aside, my English is good enough to understand what you are trying to say. And to the degree that my own words are imprecise, if you care for a more detailed and elaborate exposition of the indeterminist thesis, the Open Universe is your book. It could teach a lot in terms of adopting a human perspective on science, as opposed to God's view, which you tend to adopt a bit too easily.

You could start with the following principles:

1. In no situation can we possibly know all relevant information about a case, and even if by miracle we did know everything relevant about a case, we couldn't be sure of it.
2. We can never measure anything exactly, there's always a margin of error.
3. We can never be sure that any of our scientific theories is true.

So all we got are uncertain theories and unprecise measurements about an incomplete list of variables. Let that sink in for a second.

Now, determinism states that IF we knew with exactitude all there is to know about a state of affairs at time t; and IF we knew all the laws of nature; and IF we had infinite computation capacity; THEN we could predict exactly the state of affairs at time t + x.

The first two conditions will never be met. The third one would require infinite energy and time so it will never happen... None of these conditions will ever apply in our human lives. So much so that determinists appeal to various demons in their demonstrations, like the Laplace's demon.

Ergo determinism is perhaps a usable theory for demons, but it says nothing relevant to the human condition and the possibility of human knowledge.

In no situation can we possibly know all relevant information about a case, and even if by miracle we did know everything relevant about a case, we couldn't be sure of it. — Olivier5

If this were true, science wouldn't work, technology wouldn't work. One has to be able to know a sufficient amount of information in order to guarantee regularity of outcome and if we can do that -- which we clearly can -- then we can know what we need to know. This regularity of outcome is itself determinism.

We can never measure anything exactly, there's always a margin of error. — Olivier5

Error is not the same as non-determinism. Particle physicists can measure the magnetic moment of a neutron to within $10^-29$. That doesn't mean that because there is error, that quantity is not determined, and tomorrow someone could measure it as 1000 it's measured value. It just means there are technological limits to measurement. We would still see neutrons respond the same way to the same magnetic field, which is determinism. Error is not a path to non-determinism: non-deterministic behaviour is.

We can never be sure that any of our scientific theories is true. — Olivier5

You quote Popper like he's an authority, but demand proof? As I've said before, you don't need to know about general relativity to know that a ball on an inclined plane will roll downhill. That is also determinism.

The first two conditions will never be met. The third one would require infinite energy and time so it will never happen... None of these conditions will ever apply in our human lives. So much so that determinists appeal to various demons in their demonstrations, like the Laplace's demon. — Olivier5

That adds nothing. The above is only important IF we also wanted to know the exact position of every particle at some future date. To know whether a ball will roll downhill or uphill, none of that information is relevant.