The "free will defense" is a philosophical argument that seeks to explain the existence of evil in the world. It suggests that God granted humans the ability to make their own choices, which includes the capacity to choose between good and evil. This freedom is essential for genuine moral responsibility and meaningful relationships. According to this defense, the presence of evil is a consequence of human free will rather than a flaw in God's creation. If humans were unable to choose wrongly, they would lack true freedom, and their actions would not hold moral significance. Thus, the existence of free will justifies the presence of evil.