paradox

noun

• a seemingly absurd or contradictory statement or proposition which when investigated may prove to be well founded or true: the uncertainty principle leads to all sorts of paradoxes, like the particles being in two places at once
• a statement or proposition which, despite sound (or apparently sound) reasoning from acceptable premises, leads to a conclusion that seems logically unacceptable or self-contradictory: the liar paradox [mass noun]:Parmenides was the original advocate of the philosophical power of paradox
• a person or thing that combines contradictory features or qualities:cathedrals face the paradox of having enormous wealth in treasures but huge annual expenses