Curry's paradox
Curry’s paradox is a mischievously subtle paradox. It’s easy to miss the fact that it’s a paradox at all.
One instance goes like this: If this sentence is true, then the Moon is made of cheese. Is it true that if the statement is true, the Moon is made of cheese? Yes, if the statement is true, then the Moon is made of cheese, because that’s what it says. So, it’s true that if it’s true then the Moon is made of cheese, and since it claims that if it’s true then the Moon is made of cheese, and this claim is true, then the statement is true. And if it’s true, then the Moon is made of cheese. Therefore, the Moon is made of cheese.
That is subtle. And it can be used to prove anything (substitute for “The Moon is made of cheese”, choosing something obviously false for dramatic effect)— including contradictions— so it’s a paradox.
