affected by both genes and environment, cultural determinism and psychological determinism. Combinations and syntheses of determinist theses, such as bio-environmental determinism, are even more common. Suggestions have been made that hard determinism need not maintain strict determinism, where something near to, like that informally known as adequate determinism, is perhaps more relevant. Despite this, hard determinism has grown less popular in present times, given scientific suggestions that determinism is false – yet the intention of their position is sustained by hard incompatibilism. Metaphysical libertarianism Metaphysical libertarianism is one philosophical view point under that of incompatibilism. Libertarianism holds onto a concept of free will that requires that the agent be able to take more than one possible course of action under a given set of circumstances. Accounts of libertarianism subdivide into non-physical theories and physical or naturalistic theories. Non-physical theories hold that the events in the brain that lead to the performance of actions do not have an entirely physical explanation, which requires that the world is not closed under physics. This includes interactionist dualism, which claims that some non-physical mind, will, or soul overrides physical causality. Physical determinism implies there is only one possible future and is therefore not compatible with libertarian free will. As consequent of incompatibilism, metaphysical libertarian explanations that do not involve dispensing with physicalism require physical indeterminism, such as probabilistic subatomic particle behavior – theory unknown to many of the early writers on free will. Incompatibilist theories can be categorised based on the type of indeterminism they require; uncaused events, non-deterministically caused events, and agent/substance-caused events. Non-causal theories Non-causal accounts of incompatibilist free will do not require a free action to be caused by either an agent or a physical event. They either rely upon a world that is not causally closed, or physical indeterminism. Non-causal accounts often claim that each intentional action requires a choice or volition – a willing, trying, or endeavoring on behalf of the agent (such as the cognitive component of lifting one's arm). Such intentional actions are interpreted as free actions. It has been suggested, however, that such acting cannot be said to exercise control over anything in particular. According to non-causal accounts, the causation by the agent cannot be analysed in terms of causation by mental states or events, including desire, belief, intention of something in particular, but rather is considered a matter of spontaneity and creativity. The exercise of