Philosophy of Action

What it asks

Your arm goes up. Sometimes you raised it and sometimes it was pulled, or twitched, or rose in a spasm. The bodily movement can be identical.

So what has to be added? The obvious answer is that in the first case you intended it, and that pushes the question back: what is an intention, and how does it make the movement yours?

There is a further peculiarity. You know what you are doing without observing yourself doing it. You do not work out that you are walking to the door by watching your legs. That kind of knowledge - practical, non-observational - has no clear parallel anywhere else.

The recurring problems

Are reasons causes? Explaining an action by the reason for it looks different from explaining an event by its cause. Davidson argued in 1963 that reasons are nonetheless causes, and settled the field for a generation - but the argument creates the next problem.

Deviant causal chains. A climber wants to drop his companion, the thought so unnerves him that his grip slips, and the companion falls. The reason caused the movement, and he did not do it intentionally. Specifying the RIGHT kind of causal connection has defeated everyone who has tried.

Basic actions. You move your hand by nothing; you open the door by moving your hand. Somewhere the chain of by bottoms out, and where it bottoms out is unclear.

Weakness of will. People judge one course best and take another. Socrates thought this impossible, which shows how strange it is on reflection, and it happens constantly.

How it developed

Aristotle set the framework with the practical syllogism, in which reasoning concludes not in a belief but in an action, and with his treatment of weakness of will.

The modern field begins with Anscombe's Intention in 1957, a short and difficult book that identified action as behaviour to which a certain sense of the question why is applicable, and drew attention to the agent's non-observational knowledge of what they are doing. It is one of the few twentieth-century works of philosophy whose influence has grown steadily since.

Anscombe held that reasons explain without causing. Davidson replied in 1963 that if reasons were not causes, nothing would distinguish the reason someone acted on from the other reasons they had. That argument won, and the causal theory has been the default ever since - with the deviant chains as its permanent unfinished business.

Later work added intention over time: plans, commitments and policies, which are not momentary mental states and which do much of the work of making a person's agency coherent across a life.

The positions within it

Causalism holds that reasons explain by causing. Anti-causalism denies it. Volitionism posits acts of will as the basic elements; agent causation holds that persons cause actions, not merely events causing events. All are covered in the Schools section.

Where it stands now

The field has expanded outward from single acts. Shared agency - what it is for two people to do something together rather than in parallel - is now a substantial literature with consequences for law and for collective responsibility.

The other growth is at the boundary with automation. When a system acts on a policy a person set, locating the agency is not a puzzle case any more; it is a question courts are being asked.