Gödel's paradox: Why is "a proof that some universal statement is unprovable" not a valid proof that this statement is true?
109858
How could a statement be true without proof?
32441
How to prove or disprove statements about sets
61347
Understanding a probability paradox
78290
Countable axiom of choice: why you can't prove it from just ZF
56325
If we accept a false statement, can we prove anything?
53399
Proof of the uncountability of reals using the diagonal argument—problem?
35370
Why is this proposition provable and its converse not?
148237
Is ¬¬(¬¬P → P) provable in intuitionistic logic?
65895
Irrationality proofs not by contradiction
4700
Can paraconsistent or other logics make the impossible happen?
59908
Intuitive Explanation why the Fundamental Theorem of Algebra fails for infinite sums
73231
Why in implication, if premise is false then implication is true?
22584
Can we prove that a statement cannot be proved?
32524
Flawed proof that all positive integers are equal
130028
Why is a statement "vacuously true" if the hypothesis is false, or not satisfied?
950
Doubts on the axiom of union?
6535
Proof of for-all / there-exists "negation"?