Philosophy
Anscombe analyzes intentional action through reasons, practical knowledge and the different senses of asking why.
An action is intentional when it makes sense to ask the agent "Why?" and expect a reason in reply, not merely a cause. The answer explains what point or significance the action had for the person doing it. This is the book's proposed test for separating rational action from mere behaviour.
The book argues that an intention is not a separate inner event that comes first and then pushes the body into motion. A cause is distinct from its effect, as a thrown brick is distinct from the shattered window. An intention, by contrast, is part or aspect of the act itself, so intentional actions are not behaviour caused by intentions.
The very idea of a human action implies a subject: someone aware of what they are doing and able to deliberate. It also implies wanting, meaning felt needs that move the agent to act. Without a wanting agent, there is only movement, not action.
The book holds that practical knowledge of what you are doing still holds even when the action goes wrong. Critics object that you cannot know you are doing something you are failing to do. Many scholars still find this claim puzzling, and it remains a live point of dispute.
When you do something intentionally, you know what you are doing without needing to observe yourself doing it. On this account, intentional actions are a subclass of the things a person knows without observation. This practical knowledge is not inferred from evidence the way knowledge of the outside world is.
The book claims that the natural, widely accepted picture of what we mean by intending something leads to problems that cannot be solved. Its conclusion is that this picture should be given up, not patched. Many of the muddles about action and reasons are traced back to this starting picture.