In philosophy, an action is an event that an agent performs for a purpose, that is guided by the person's intention. The first question in the philosophy of action is to determine how actions differ from other forms of behavior, like involuntary reflexes. According to Ludwig Wittgenstein, it involves discovering "[w]hat is left over if I subtract the fact that my arm goes up from the fact that I raise my arm". There is broad agreement that the answer to this question has to do with the agent's intentions. So driving a car is an action since the agent intends to do so, but sneezing is a mere behavior since it happens independent of the agent's intention. The dominant theory of the relation between the intention and the behavior is causalism: driving the car is an action because it is caused by the agent's intention to do so. On this view, actions are distinguished from other events by their causal history. Causalist theories include Donald Davidson's account, which defines actions as bodily movements caused by intentions in the right way, and volitionalist theories, according to which volitions form a core aspect of actions. Non-causalist theories, on the other hand, often see intentions not as the action's cause but as a constituent of it.
An important distinction among actions is between non-basic actions, which are done by doing something else, and basic actions, for which this is not the case. Most philosophical discussions of actions focus on physical actions in the form of bodily movements. But many philosophers consider mental actions to be a distinct type of action that has characteristics quite different from physical actions. Deliberations and decisions are processes that often precede and lead to actions. Actions can be rational or irrational depending on the reason for which they are performed. The problem of responsibility is closely related to the philosophy of actions since we usually hold people responsible for what they do.
Conceptions
Conceptions of action try to determine what all actions have in common or what their essential features are. Causalist theories, like Donald Davidson's account or standard forms of volitionalism, hold that causal relations between the agent's mental states and the resulting behavior are essential to actions. According to Davidson, actions are bodily movements that are caused by intentions in the right way. Volitionalist theories include the notion of volitions in their account of actions. Volitions are understood as forms of summoning of means within one's power and are different from merely intending to do something later. Non-causalists, on the other hand, deny that intentions or similar states cause actions.
Davidson's account
The most well-known account of action, sometimes simply referred to as the standard account, is due to Davidson, who holds that actions are bodily movements that are caused by intentions. Davidson explains the intentions themselves in terms of beliefs and desires. For example, the action of flipping a light switch rests, on the one hand, on the agent's belief that this bodily movement would turn on the light and, on the other hand, on the desire to have light. Because of its reliance on psychological states and causal relations, this position is considered to be a Humean theory of action. According to Davidson, it is not just the bodily behavior that counts as the action but also the consequences that follow from it. So the movement of the finger flipping the switch is part of the action as well as the electrons moving through the wire and the light bulb turning on. Some consequences are included in the action even though the agent did not intend them to happen. It is sufficient that what the agent does "can be described under an aspect that makes it intentional". So, for example, if flipping the light switch alerts the burglar then alerting the burglar is part of the agent's actions. In an example from Anscombe's manuscript Intention, pumping water can also be an instance of poisoning the inhabitants.