A non-mathematical universe[1] may also be deterministic, but determinism is still not normative. A person may be predetermined to murder someone, but that does not necessarily imply (although it may relate to) the religious norms regarding murder. Some religions believe in predestination and determinism (fatalism) regardless of physics, and yet still make normative requirements.

As long as he doesn't say how people should behave, this isn't religion (even if it relates to how people will behave).

[1]: I.e., assuming a distinction between physical and mathematical

> Well, it's even stronger than most religions in specifying how humans will behave, which of course includes should.

I think that the 'of course' here is not at all obvious. Economics, for example, seeks to describe how people will behave, but neither makes nor, I think, is perceived to offer any description of how they should behave (at least not in any moral sense).

I disagree. should is only relevant when there is a choice. Under the MUH, it's like saying 1+1 should = 3, which is fairly meaningless. Basically, the MUH answers the should question which is why it qualifies as religion. It's answer is "it's irrelevant".

Well, people have literally spent millennia arguing over this. I doubt this could be resolved in a HN comment :)

Anyway, even a deterministic universe (mathematical, i.e. monistic Platonistic, or otherwise) is still undecidable/intractable, and so normative prescriptions may well serve an important role as you don't know their place in the causal chain.

Of course, you could argue that "importance" is also a subjective measure in a deterministic universe, and an irrelevant one, but then so is "relevance" itself.