Let me try to explain it all the way from a base assumed axiom.
#1: We are not in any version of in effect the evil demon, vat in a brain, Boltzmann Brain universe, multiverse computer simulation.
That we're a dream in the brain of a superior being, an element in a Tron game, an experiment by multiverse scientists, that the universe, Boltzman-style sprang into existence fully formed last Thursday, and so on, are all unfalsifiable and therefore not regarded as scientific propositions. Their relevance arises when claims are made that a particular statement is absolute ─ to be absolute, it would have to refute all such ideas (or, I guess, conform to only one of them).
it means that we can't assume that there are universal natural laws that governs the universe. That is a separate assumption.
As I said above, I think it's justified by induction, not merely by assumption, in that as a rule of procedure it's worked very well ─ but that doesn't excuse science from being alert to any signs of exceptions.
We assume that we are in a universe
As I've said more than once before, you and I share the assumptions that a world exists external to us, that our senses can inform us of it, and that reason is a valid tool.
the problem of "das Ding an sich"
Dings in siches are not an idea I hold with. Instead I approach such questions through how we form and use concepts.
we test and we test if any test has a limit for what it can test. Or in other words we test any methodology for its limits and we don't assume that any methodology is universal and applies to all of the universe.
Yes, we're inductively entitled to proceed on just that basis, as long as we remain alert for contraindications.
So now you are in effect a general skeptic and not just skeptical of the religious and related variants. You test the limit of reason. logic, any claim to a methodology of evidence other than logic and you figure if even reason, logic and evidence have limits.
I haven't disagreed with that, as far as I can recall.
So are you willing to test if there is a limit to your assumption that reason is a valid tool?
A fair question. But the very reason it has to be an assumption in the first place is that there doesn't appear to be any way of testing it that doesn't involve reason, If you have such a test, I'm happy to learn more,