The irresistible force paradox, also called the unstoppable force paradox, is a classic paradox formulated as "What happens when an unstoppable force meets an immovable object?" This paradox is a form of the omnipotence paradox, which is a simple demonstration that challenges omnipotence: ("Can God create a stone so heavy that not even God is strong enough to lift it?"). The immovable object and the irresistible force are both implicitly assumed to be indestructible, or else the question would have a trivial resolution ("it destroys it"). Furthermore, it is assumed that they are two separate entities, since an irresistible force is implicitly an immovable object, and vice versa.
The paradox arises because it rests on two premises—that there exist such things as irresistible forces and immovable objects—which cannot both be true at once. If there exists an irresistible force, it follows logically that there cannot be any such thing as an immovable object, and vice versa.