My own reasoning in regards to this matter is, if determinism is not true - which is to say, if there are events in the history of the universe which, if played back again under the exact same prior conditions, might happen differently - then it seems to me that those events didn't have "sufficient reason" to occur.

A sufficient reason I'm interpreting to be something like "an explanation for why this occurred instead of something else".

If that's the case, then quantum indeterminacy would seem to imply the PSR is false. However, the PSR seems generally applicable, except for this one exception, so it would then make sense to revise the PSR to allow for probabilistic determination: asserting that the outcome of a quantum collapse is sufficiently determined by a probability distribution.

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then quantum indeterminacy would seem to imply the PSR is false. — Relativist

For some, perhaps most, interpretations of qm, yes but not all.

But the PSR doesn't have to be true. If a non deterministic interpretation of qm is true, then the response isn't necessarily to revise the PSR, it might just be to reject it. "The world isn't deterministic, and there are things that happen that have no sufficient reason - they just happened"

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idk what's reifying about it. I'm just asking if one idea being true would imply another idea is true. I'm not certain either of the ideas are true myself, but I think they're both intelligible enough to ask the question.

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Wouldn't that just mean that insofar that determinism is true there is a/(some version of the) PSR must be true, namely, the one wherein reasons are causes and there are no other explanations worth considering with respect to the PSR, or something like that.

I think I'd be more inclined to accept the inference from determinism to the PSR than the inference from the PSR to determinism just because reasons and causes need not be one and the same, so it seems obvious to me that one can hold that everything has an explanation without everything having a cause.

if everything has an explanation, but determinism is not true, the problem for me is, where's the explanation for the undetermined event?

If we look at some event that, given all the facts about the universe, could have gone one of two ways, and we ask "why did it go this way instead of that way?", well if indeterminism is true then you can't answer that by pointing to any fact about the universe. That seems very anti PSR to me, you know?

↪Moliere if everything has an explanation, but determinism is not true, the problem for me is, where's the explanation for the undetermined event? — flannel jesus

Isn't "That's a self-caused event" a sufficient explanation for an uncaused event? Or "These events are the stochastic events"?

you could say that but it seems like that undermines PSR entirely. You could just say that for anything, and then nothing needs an actual explanation, because everything is just self caused.

Self caused why though? Right? Why did it cause itself?

And if it's sufficient, then the question would be why doesn't that thing always happen under those conditions? "The conditions were sufficient for this thing to happen, but it didn't happen anyway"... Maybe I'm misunderstanding what sufficient means, but it doesn't seem like that's how sufficient works.

If a non deterministic interpretation of qm is true, then the response isn't necessarily to revise the PSR, it might just be to reject it. — flannel jesus

The PSR can be considered the underpinning of science: the pursuit of answers to why something is the way it is. So I think there's something worth salvaging.

How about grounding? A quantum collapse is grounded in the quantum system, and possibly the entity that it becomes entangled with that results in the collapse.

I imagine that the explanation is unsatisfactory, generally speaking, but we'd reach for it in the event that we have reason to believe such-and-such a kind of event is, in fact and not just because of how we calculate things, stochastic.

So if we simply accepted "Self-caused" for all events then that's deeply unsatisfactory, and there I'd say yeah pretty much amounts to denying what the proponent of the PSR is wanting to say.

But given the difficulties there are in claiming quantum events being deterministic that seems to me the most obvious example that we'd reach for. Why did it cause itself? For the same reason that A necessitates B -- that's just how it works.

In a way the explanation in operation in both cases, be it deterministic or stochastic, is an appeal to an events being -- the kind of being it is is what explains how it behaves. Deterministic events necessitate, and stochastic ones do not, and the PSR could be taken as a regulative rather than factual principle whereby the termination of thought into self-caused events is acknowledged as unsatisfactory, and so be on the lookout to see if we missed something after all.

"The conditions were sufficient for this thing to happen, but it didn't happen anyway"... Maybe I'm misunderstanding what sufficient means, but it doesn't seem like that's how sufficient works. — flannel jesus

In the case of a stochastic event I'd imagine we have to say "The conditions were sufficient for 50%A/50%B, and we observed A this time" -- or B. And then, if truly stochastic, you'd predict that with repeated measurements of the same system-event you'd begin to see the distribution emerge, whatever distribution that happened to be for that phenomena.

The PSR can be considered the underpinning of science: the pursuit of answers to why something is the way it is. — Relativist

Science certainly is searching for explanations, but I don't think science strictly needs it to be metaphysically true for EVERYTHING to have an explanation.

case of a stochastic event I'd imagine we have to say "The conditions were sufficient for 50%A/50%B, and we observed A this time" — Moliere

And the "A this time" would still be insufficiently explained, that's the problem, that's the disconnect between indeterminism and PSR.

Like I totally agree that you can have a determined and explained probability distribution in QM, but that last bit, that "A this time instead of B", just seems to pop out of nothing.

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I don't think science strictly needs it to be metaphysically true for EVERYTHING to have an explanation. — flannel jesus

So some things have explanations. Seems so weak, it's irrelevant.

I don't understand. What seems so weak it's irrelevant?

If only SOME things have explanations, then there's not much impetus to seek one.

Where I wanted to go with this, is to narrow down the sorts of things that have explanations.

Does it pop out of nothing anymore than the belief that A necessitates B pops out of nothing? Is there a cause for the necessary connection between causes, and so forth on back? Or does explanation eventually end, and we can still be rational for all that?

if some things have explanations, then there will always be some utility in understanding them.

I think, even if we do live in a world with quantum randomness, when it comes to the kinds of events we're interested in at our macroscopic scale of existence MOST things have explanations. It doesn't necessarily hurt all that much if some tiny things don't.

I certainly think there's probably a brute fact somewhere down there, and that would pop out of nothing, yes, and that would arguably undermine PSR. I think things popping out of nothing do undermine the PSR.

But they might undermine the PSR in different ways.

Like maybe you could say "The PSR is true except for these small amount of axioms with no explanation". And that's just a little bit of non-PSR in the world.

Or you could say "The PSR is true except for literally every single quantum event", and then suddenly you have a lot of non-PSR in the world.

Here's what I was thinking.

The things that lack explanations, are brute facts. So we should always seek explanations, but accept that there are instances where we will hit a brute fact.

Example: assume metaphysical foundationalism is true (i.e. there's a "bottom layer" of reality"). That layer is not explainable in any deeper terms.

I think insofar that such explanations don't amount to "Just because" then they could still count as good enough for the PSR, but not good enough for determinism. So perhaps an explanation for stochastic events is that there are two kinds of events, deterministic and stochastic. So insofar that we are willing to accept that there is such a thing as metaphysical cause at all it seems that the hard commitment is already done with -- it's easy enough to suppose that there could be two kinds of causes, to my mind.

But then this wouldn't be a brute fact if we are following along with the PSR -- perhaps it's a regulative fact, though there's some further reason why our explanation ends with causation -- like we cannot comprehend events outside of the structure of causation, for instance. That doesn't mean there are no such events, only that we wouldn't be able to comprehend them, and this is why explanation must terminate in cause -- see how this satisfies the notion that everything has a reason, even if that reason is not a cause?

It's a Be-cause, but not a metaphysical cause.

see how this satisfies the notion that everything has a reason, even if that reason is not a cause? — Moliere

No not really. It still seems like there are things that don't have reasons in that case to me. Maybe I'm just being stubborn or something, but I don't see it.

If qm dictates that you see A 50% of the time and B 50% of the time, then the question "why did I see A instead of B this time?" still seems reasonless to me.

Suppose the case with a quarter -- why did you see heads this time and not tails? Well, because 50% of the time you will see that and 50% of the time you won't, and this is only one time so you had to see one or the other.

that sounds like a "no particular reason" flavour of answer to me.

The OP's question has to do with possible connection, reified into possible existence. Until the terminology nailed down on four corners, unanswerable in any but speculative terms. As to QM, the language of description - which is after-the-fact and tentative - seems to be implied to have a causative power, and I do not see how that can be. — tim wood

I don't understand what you're saying. Reified? That entails a fallacy. Do you mean actualized?

Under QM, a pure state quantum system evolves deterministically- per the wave function, describable by a Schroedinger equation.