For those who remain unconvinced that moral responsibility and freedom are compatible with determinism, this chapter will provide a number of alternatives. Libertarianism is a kind of incompatibilism according to which authors sometimes have free will. There are three basic varieties of libertarianism: simple indeterminism, event-causal libertarianism, and agent-causal libertarianism. Simple indeterminism (sometimes called non-causal libertarianism) is the view that when authors act freely there is an uncaused basic mental action. A basic mental action is just what the name implies. In the philosophical study of human action there is a longstanding debate between causalists and non-causalists about reason explanations. Causalists say that reasons must be causes in order to explain the action. Non-causalists often say that reasons provide teleological explanations. For a long time, the debate between compatibilists and libertarians was really a debate between causalists and non-causalists.