Predictability Problems in Physics

I dispute this. Weather is not predictable. People are not predictable. Stocks are not predictable. All these are chaotic systems too. A large proportion of what we deal with in life is neither predictable nor deterministic from a human point of view.

Chaotic systems are an important example. They are, in principle, predictable. However not practically so, because we do not have perfect knowledge.

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I think we should separate predictability and determinism. In the classical picture, in principle most things exactly follow Newtonian mechanics and we would be able to predict it if we had enough computing power. Thus, they are deterministic - they follow certain rules exactly. Chaotic systems in classical physics are also in principle deterministic in this way, even if they are not predictable.

Now, one could argue that if one can’t produce an equation that accurately predicts the behavior of a system, one has not showed that that system is actually deterministic. In other words, even if Newtonian mechanics assumes determinism (except for the edge cases), we have not proven that nature
follows it exactly. Nancy Cartwright has argued against this sort of “physics fundamentalism” in her paper Fundamentalism and the Patchwork of Laws. I appreciate her argument, but it is an argument about nature and whether classical physics applies to it, not classical physics itself. Whereas here, here we are assuming that classical physics applies to all of nature. (Even though we know that it doesn’t because of QM and so on.) We have to use this assumption because otherwise there is no real way to calculate P(X). To calculate P(X) we have to assume some theory of nature.

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Okay, so you are saying the weather is deterministic, but not predictable. Okay. However, I do not think we know whether people are deterministic or not. Even from a purely scientific point of view, it is possible quantum noise might be important in neural circuits:

Considering that we are social animals. Just about our entire world is not predictable, and possibly not even deterministic.

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You would also need the initial conditions for everything, or conditions at some starting point from which we could begin computing.

I’m inclined to disagree with that.

Newton’s mechanics is itself deterministic. But I don’t think there’s a required assumption of determinism.

I remember struggling with this several decades ago. The world does not look deterministic, even if only because human behavior does not look deterministic. I eventually came to a way of understanding Newton’s mechanics which did not imply determinism.

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I agree that that is a tantalizing possibility. After all, once we put quantum mechanics in the picture determinism goes out the door entirely. (Although, yes, we do not know if quantum indeterminacy at the micro-, particle level has non-trivial macro-level consequences.)

I have no idea whether people are deterministic or not from a theistic point of view. We would have to get into the issue of God’s foreknowledge vs. determinism, and libertarian vs. compatibilist free will. But my original intention of responding to this issue was regarding Eric’s probabilistic formulation of teleology. In that case, I believe he thinks it is also applicable to teleology in the things of nature, such as heat-seeking missiles. So people are not what we’re talking about.

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I think we are saying the same thing. Newtonian mechanics is deterministic. We don’t know if nature is deterministic. Thus we are also saying that we don’t know if nature follows Newtonian mechanics exactly. (This is even without bringing QM into the picture.)

Can you explain that a little more?

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I’ll disagree with that. We do know that there are non-trivial macro-level consequences.

There are numerous research papers on quantum indeterminacy. A published research paper is a non-trivial macro-level consequence.

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That’s an interesting way to look at it. But that macro-level consequences involves human agents. And human agents, with free will and all the uncertainty and unpredictability that comes with that, are difficult to incorporate into physics as part of the theory itself. So I guess what I’m saying is that we don’t know if there are entirely natural, mechanistic macro-level consequences.

Let me add a quick comment on this:
Norton’s dome is indeed not an issue, because it requires very specific configurations. However, space invaders are problematic because one does not know when/whether the invader appears prior to it appearing. In other words, in a world with only classical mechanics without SR, there is no way to know that we are in a daily life situation that are in principle deterministic.

As I mentioned in a previous post, if one gives up locality, it is possible to have a deterministic QM. One can also have a (in my opinion nonelegant) deterministic Relativistic QM. I believe the jury is still out on whether there is a field theory extension to deterministic QM. However, giving up locality might run afoul on how one would evaluate Eric’s P(X)'s in practice. I am not sure on this point.

Chaos is an example where predictability can fail in the following sense: given any computational resolution, for a chaotic system I can come up with a configuration that a computer with said resolution will get the time evolution wrong.

I agree with @dga471 that we should separate determinism and predictability. However, I believe that if either determinism or predictability fails, Eric’s P(X) program is not tenable. If determinism fails, P(X) is never 1, while if predictability fails, it is not possible to evaluate P(X) to test the theory.

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Yes, it does. But they chop down a bunch of trees to make paper for printing those research papers. And that’s a macro-level consequence that physics can observe, though it still involves human agents.

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Yes. Besides non-locality, one could ensure determinism with QM via the superdeterministic loophole. Basically, our choices are not truly free, even when conducting scientific experiments. Sort of like the quantum version of the Omphalos hypothesis. While this is extremely unpalatable from a purely scientific perspective (as it is unfalsifiable), it occurred to me that it is possible that from God’s POV something like this is the case.

If predictability fails for some cases but not others (while determinism still holds), one could just say that we can prove teleology exists for some systems but not others. I think that would be good enough for a lot of people.

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I’ll try to get to this tomorrow.

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Sure, the printing of the paper could be analyzed using physics. But physics can’t show that the printing of the paper was caused by certain people understanding things about quantum mechanics. (“Understanding” is not a rigorous physics concept.) For that you need sociology (or common sense :sweat_smile:). Because it can’t analyze the causal link that is crucial to macro-level consequences, it can’t prove that there are macro-level consequences.

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Hmm, this is an interesting thought on superdeterminism. I have to give it more thought.

I think I agree with this.

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Yes that is correct. It is one of many challenges to ASC (@EricMH). Even if we had all the natural laws, we do not expect the will allow us to compute P. Moreover, there is always a possibility that it is an unknown law creating an unaccounted for pattern.

In the case of DNA I can present examples of DNA patterns that we do not how they were produced. We can imagine what might cause these patterns but we have not yet proven it. So I’d add that we don’t have all the laws in view either in biology.

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This ignores the elephant in the room, free will.

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Superdeterminism is an interesting idea to consider more generally when you think about the scientific studies on miracles or intercessory prayer that has been done and found negative results. Or why it is generally not fruitful to consider God as a “scientific hypothesis.” From a theological perspective, it could be the case that “Do not put the Lord your God to the test” (Luke 4:12) means that for certain things (such as miracles, prayer, or interaction with God in general), we do not have true freedom of choice as God does not intend us to do scientific experiments for those things.

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I think in general, Eric’s definition of teleology is meant to be applied to either non-living things or things without a clear sense of free will (such as lower-level animals and organisms)?

@EricMH is putting forward a version of vitalism that inlcludes all life. I don’t think we can make any assumptions on his view. It is not clear how his version of vitalism interacts with all this. We are far afield.

He claims if something certain, he has proven teleology. He does not specify if he means certain from a human or divine point of view. He is not clear.

Moreover teleology refers to purpose, not inevitability. I am 100% sure I will eventually die. This does not meant it is my purpose to die. I’m certain we will all sin, but that does mean our purpose is to sin. The fact that some things are in principle deterministic does not at all imply teleology. If such a definition were sensible, purposes could never be frustrated, and therefore could never in conflict. I submit that @EricMH’s notion of teleology is not coherent.

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Yes, from this and trying to follow your conversation with @EricMH, I think there is something fishy with this whole ID information theory project to mathematically prove or formulate teleology (or design). It seems to be mixing a mechanistic picture of the world (or at least mechanistic methods) - the things that @Eddie likes to complain about, for example - with Aristotelian goals. This is why it ends up with awkward conclusions or mathematical proofs with questionable applicability to the real world. The two paradigms seem to be fundamentally in tension, so it is hard for them to work together.

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