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Do we really know anything?
(i.imgur.com)
General rules:
Exceptions may be made at the discretion of the mods.
we know math, 1+1=2, 2+2=4
really hard if not impossible to convince people otherwise
once you've set the axioms of math, everything else follows
Math is not really "knowledge of the universe" though, it's just the symbols and syntax we use to help map it when we try to understand the universe (through physics, chemistry, biology, etc.). Now, the maps that we have through maths can be extremely useful and very accurate to/representative of reality, certainly.