For the use of the term "libertarianism" in politics, see libertarianism (politics).
In philosophical debates about free will and determinism, libertarianism is the belief that human action is not determined. Most libertarians subscribe to the philosophy of incompatibilism which states that reality is indeterministic. A free action is considered one which is not determined. In a way, that would mean that a free action is simply a random event, which seems contradictory since such an action would lack purpose. Some libertarians take the philosophical view that determinism and free will are compatible. They believe the fact that one's choice may be in theory determined or predictable, does not alter the fact that it was a free choice. For example, being able to predict that someone will not cross the street when a car is coming, is not taken to imply the person has no free will. He makes that choice because he wants to live. We may be able to predict that choice, because we know the person enjoys life, but it is still the case that the person chose what he wanted to choose.