Tag Archives: indeterminism

Re-running The Universe: Determinism, Indeterminism, Quantum Stuff

[This is part of a set: Thinking]

The philosophical persuasiveness or either determinism or indeterminism has been made foggy by the success of quantum physics, in particular the apparent indeterminate nature of the world, that is the result of quantum physics.

One question that arises is the extent to which we can be sure, or not, that the universe is deterministic. Does ontological determinism hold?

[This follows from another post which assumed determinism for the points made. It ignored quantum stuff.]

From the point of view of a scientist there is the laudable position that we go wherever the evidence leads – and I agree with that. It appears that all the science is telling us that we live in a quantum indeterministic world, but with determinism at the macro level that allows us to make limited predictions.

So, if anyone wants to argue on the basis of evidence, then that’s it. The world is a deterministic+indeterministic mix. But it is indeterminate anyway, epistemologically, to those entities within it.

At our macro level we can still argue that there is a determinism that appears as a result of any quantum event, once it has occurred. Once a particle has had a causal effect on another, to a measurable degree, then the outcome is, within limits, deterministic.

One question that often arises is this. If we ran the universe again, would all the same events occur? The quantum non-determinist would say that, no, it would not, because quantum events are by nature indeterminate and would result in a different outcome.

But, given that we can’t re-run the universe this is a speculative position. Here I give several alternatives that I see. What follows assumes there is some sort of existence of something outside our universe – that our universe is contained in some way, so that the starting conditions can be set up the same way, down to whatever detail one might like to speculate about.

Determinism seems to require causality, otherwise what does it mean for one state to be determined by prior states. On the other hand, if there is a genuine time symmetry, then effects would cause causes, when considering time reversal. A one-way time dimension can also be causal the one way (which is what we perceive), and yet even in this universe Galilean physics is time reversible. Anyway, putting time issues to one side for now, here we go:

1) Indeterminate Universe. In this case there might or might not be causal relationships. It might be the case that there is no causality, just correlation – weak observed correlation. How does a completely indeterminate universe allow for predictability? Maybe it doesn’t. Maybe what we perceive as repeatable predictable outcomes – say from y = mx + c – are just coincidental correlations. If the universe is so indeterminate in actuality, in practice it’s difficult for us to figure that out, to ‘determine’ its indeterminism, as it were. This is somewhat like the reality-solipsism dilemma – we can’t tell the difference. The point though, in the context of this post, is that to re-run this universe with the same starting conditions will result in a different universe each time.

2) Deterministic Universe. In such a universe every event is determined causally by prior events. This is a point of view that might have been held prior to our discovery of the quantum indeterministic nature of the universe. In such a universe it would re-run exactly as it did on a previous run. On the face of it, at the macro level, it seems a reasonable working hypothesis. We observe what we think are deterministic connections on many levels of science, and other than quantum indeterminacy, we’ve observed no evidence against determinism.

3) Quantum Indeterminate Universe. In such a universe, even with identical starting conditions, the re-run would produce a different universe, because of the truly indeterministic nature of quantum events. This seems to be how some scientists view the consequences of quantum physics in our particular universe. But this seems to require some knowledge of facts outside our scope. Consider, if the quantum indeterminacy is, at some other level, actually determinate, but our understanding of physics is mistaken, then how would we tell the difference? Only a re-run of this universe would reveal the true quantum indeterminacy because a different universe would appear on each run.

4) Quantum Determinate Universe. In this universe even the quantum events are determined – though I refuse to speculate on how that might occur. Note though, that to the entities contained within each ‘run’ of that universe the quantum events would still be non-deterministic, because those entities are contained within the re-running universe and are bound by the evolving quantum events that are taking place. So, on each re-run, the inhabitants of the universe are convinced that their universe is non-determinate because of the observed quantum events, and yet on each re-run the very same quantum events are occurring, deterministically, and each re-run produces an identical universe.

Now, (4) is purely speculative of course. But then so are all of these options, because we don’t have a view of our universe from the outside and over re-runs of it. So, I don’t see any justification for being dogmatically committed to any of these views.

Perhaps the important point is that we do not know what our science is telling us about the deep status of our universe. It is all metaphysical speculation. And, I repeat an earlier point, to us it’s all indeterminate anyway. We cannot tell the difference between a determinate and an indeterminate universe if we ar a part of it.

Ontological Determinism, Epistemological Indeterminism, Laplace’s Demon

[This is part of a set: Thinking]

What follows is putting aside any quantum stuff for the purposes of this point about the difference between ontological determinism and epistemological indeterminism. Adding ontological indeterminism, through quantum indeterminacy or some other means, doesn’t really alter the points made. It also ignores relativistic effects.

This is purely about classical determinism and how, if that were the case in our universe, we still have problems of indeterminism. It’s also about the implications for our view of free-will.

But it begins with a response to some fears of determinism.

In Sean Carroll’s post on Determinism (in the context of Free will) a comment by Katherine included two quotes. One was from Stephen Hawking:

The ideas about scientific theories outlined above assume we are rational beings who are free to observe the universe as we want and to draw logical deductions from what we see. In such a scheme it is reasonable to suppose that we might progress ever closer toward the laws that govern the universe. Yet if there really is a complete unified theory, it would also presumably determine our actions. And so the theory itself would determine the outcome of our search for it! And why should it determine that we come to the right conclusions from the evidence? Might it not equally well determine that we draw the wrong conclusion? Or no conclusion at all?

Well, “Yes” to the last two questions, and “It needn’t” to the first of the last three.

Katherine also quotes Conway and Kochen in a similar mood:

It is hard to take science seriously in a universe that in fact controls all the choices experimenters think they make. Nature could be in an insidious conspiracy to ‘confirm’ laws by denying us the freedom to make the tests that would refute them. Physical induction, the primary tool of science, disappears if we are denied access to random samples.

Well, so what. To paraphrase Lawrence Krauss, science tells us how the universe is, not how we want it to be. If we learn from science that the universe is deterministic, and it happens to be that way, then yes, that determinism determined that that is what we would find. And if we conclude it isn’t deterministic and yet it actually is, then determinism has determined that we make that mistake. We’re stuck with that. Does that make you, the budding Nobel Physicist just embarking on your studies give up and throw in the towel? Well, that was determined too. It’s no good denying determinism because we don’t like it. We should only deny it if we figure out that it isn’t the case (and accept we may have been determined to make that mistake).

If the universe is totally deterministic then that is what it is. If we do eventually observe that this is the case, then this is what we observe, no matter how much it messes with our minds (which too would be determined, obviously). It could be that the determined universe does determine evolution and that our current interpretation of evolution is describing how we see it so far. Natural selection would then simply be the determined outcome of prior states and processes.

A different deterministic universe might have determined no evolution and no entities with self-awareness that could observe the universe the way we do. It’s laws may have had room for evolution, but it simply might not have occurred given the a different starting state.

The Conway and Kochen paper was intent on saving free-will, which seems to be necessary for some people. But why the desire to save free-will? Now, I don’t think we have free-will, that is real free-will beloved of dualists and theists. I do actually think, for now, that we are effectively mechanistic systems. What I’m not clear about is the extent to which determinism holds (given that there are possibilities that allow for quantum mechanics being deterministic – the jury is still out). But I don’t think that has any consequences for any physicalist version of free-will that matters.

So, whether we like it or not, no matter what the implications are for free-will, what if the universe is actually deterministic?

Thinking for the moment about entities within the universe, I don’t see how determinism precludes there being such entities that observe and alter the universe (i.e. ones that do science). It just means that the altered states are just more bits of the determined outcome.

There’s a significant difference between a deterministic system and the capacity for some entity to determine (calculate) its states – the capacity to actually do the math to predict some total state in the future. That a system is deterministic does not require that the system, or any bit in it (e.g. us) actually has to do any predicting of any sort. It just plays out, as determined by its laws (as those laws are, not necessarily as we currently understand them).

Determinism rarely requires that perfect prediction be practically possible – only prediction in theory. – Wiki on Determinism.

To actually determine any one complete state from the starting state you must be an outside observer. The problem for an observer inside the system being observed is that they are part of the system. The observer needs the capacity (e.g. memory + processing system) in order to contain every little detail of the system. But then that capacity (memory + processing system) is also part of the observed system, and so you need more capacity to store data about the state of that sub-system, … This is part of the point of Laplace’s demon, that requires ‘arbitrary’ capacity to do the maths. Perhaps it should be phrased as ‘adequate’ capacity, and it should be made clear that the demon can’t be part of the system.

So, even if the universe is ontologically deterministic, it must be epistemologically indeterminate to internal entities.

Whether it is epistemologically deterministic to external entities is another matter – e.g. Leplace’s demon, God or some other deity, or some other non-intelligent entity like a universe-computer.

But I don’t see reason to suppose that a deterministic universe requires either an observer, or a creator. We have a dataset of 1, as Neil deGrasse Tyson is fond of pointing out. We haven’t the slightest clue as to what’s required in the business of universe creation (active agent) or coming into being (passive mechanistic systems).

The only practical matter for now, to us, is that the universe is practicably indeterminate, because we’re in it. Quantum effects only add to that indeterminacy. In this sense, whether ontological determinism actually holds or not isn’t important.

But as a convenient model determinism is helpful because it should make us think twice about attributing mysterious explanations (like dualist free-will, or the soul) to indeterminate events, or attributing agency where we have no reason to. If we can overcome the fear of determinism and its threat to our hubris of being human and special and immune to the discoveries of science, and just be prepared to face up to what science exposes of the universe to us, or about us, then maybe we can move on from some of the ancient myths that still hold us back.


See also: Re-running The Universe: Determinism, Indeterminism, Quantum Stuff