The problem of free will is the problem of whether human beings exercise control over their own actions and decisions. Addressing this problem requires understanding the relation between freedom and causation, and determining whether or not the laws of nature are causally deterministic. The various positions taken differ on whether all events are determined or not—determinism versus indeterminism—and also on whether freedom can coexist with determinism or not—compatibilism versus incompatibilism. So, for instance, hard determinists argue that the universe is deterministic, and that this makes free will impossible.
The principle of free will has religious, ethical, and scientific implications. For example, in the religious realm, free will may imply that an omnipotent divinity does not assert its power over individual will and choices. In ethics, it may imply that individuals can be held morally accountable for their actions. In psychology, it may imply that the mind controls some of the actions of the body. In the scientific realm, it may imply that the actions of the body, including the brain, are not wholly determined by physical causality. The question of free will has been a central issue since the beginning of philosophical thought.