There's a class of propositions we could call "effect-indistinguishable" which can have no possible effects which distinguish between their truth and falsehood

There's a class of propositions we could call "effect-indistinguishable" which can have no possible effects which distinguish between their truth and falsehood (eg., that a god exists with no spatiotemporal location and no causal effects, etc.). If these are true, they do have genuine implications (eg., a world with such a god is different than one without). However, I shortcut all this with a simple meta-epistemic principle: I will never believe one of those propositions on the basis that it could never be rational to do so. I take it is the most rational belief in this case is simply to presume they're all false, since there are an infinite number and i think some argument can be made that theyre certainly largely false since most are contradictory (etc.) So, no the universe is not a simulation; nor a dream of a demon; nor one of any of these propositions. If you think it is, then why not draw randomly from a similar set? Why not the wish of an alien honoured by a angel? These kinds of propositions are "failure modes" of rational thinking that cannot be addressed in their own framing (consider, by analogy, "is the king of the US bald?"). The response has to be about what it means to think at all, to believe something is true, and so on. This is also how to address conspiracy theories. The issue with them is their belief in classes of propositions of this kind (eg., that all "official" claims are false).