Alvin Plantinga's version of the free will defense is an attempt to refute the logical problem of evil: the argument that the existence of an omnipotent, omniscient, omnibenevolent God in an evil world is a logical contradiction. Plantinga's argument is that "It is possible that God, even being omnipotent, could not create a world with free creatures who never choose evil. Furthermore, it is possible that God, even being omnibenevolent, would desire to create a world which contains evil if moral goodness requires free moral creatures."