Asklemmy

My simple uncontroversial claims

None of these is uncontroversial, C isn't even well-defined. I'd argue that B is correct only if A is correct. And A cannot be correct, since it leads to multitude of cotnradictions, one of which I'm going to demonstrate.

It appears from context to be the first: the claim that indeterminism means events are not explained by their causes. But that’s just the definition of indeterminism

No, it most definitely is not. If you used this as a definition, I'm fairly certain that most physicists would absolutely not agree with your B.

If you deny that indeterminism means things aren’t determined by observable causes, then what does it mean?

Indeterminism means that if an experiment is repeated with the same parameters, there are no guarantees to get the same result. Nothing more than that.

Your definition implies that there needs to be a cause in the first place. And that is bordering on begging the question, because with that definition you are guaranteed to reach a point where there is something "unexplainable" (since there are infinite amount of layers), which can always be attributed to whatever supernatural thing you choose. There is absolutely no need for this to be the case.

In fact, you yourself quoted the textbook

the outcome is intrinsically random.

Emphasis mine. That means, there is no cause, it's an intrinsic property of the theory, especially in Copenhagen interpretation, which is the status quo. As your definition implies a cause, it cannot apply here. There are other contradictions, but this one is simple and I only need one to show that the premise is flawed, and your other points rely on that.

you have not substantiated your claims with anything.

My only claim is that you are incorrect. There aren't really too many papers written about that. (I hope) I've shown your premise to be false because of faulty definitions, what more would you need? None of the stuff you quoted is supporting you, and in fact contradicts you, unless we specifically assume that other people use the definition you've given, which, again, is already shown to be erroneous.