Troglodite thinking:
Opinion - Something you believe to be true based on no or limited evidence.
Fact - A thing you believe to be true that is objectively true.
Enlightened thinking:
Opinion: Anything I believe to be true whether it is true or not and no matter what level of evidence I believe I have.
Fact - A thing which an oracle could, would know is objectively true, but since oracles dont exist we can never exert with certainty that something is or is not fact. It is at best an abstract concept.
> I feel like there's got to be a limit.
> Is "1+1=2" opinion?
If you mean that "1+1" has the only possible and calculable result "2", then yes it is an opinion 🙂
We cannot prove that mathematics is consistent. So, if we find an error in current axiomatic systems, we can then prove that "1+1=3", too.
We believe that mathematics, as formalized today, is consistent, and that in case there are errors in its foundations, they can be fixed without affecting the majority of useful theorems and result we have now.