Definition
Detachment from outcomes is the Stoic discipline of separating one's effort from one's results. A Stoic commits fully to acting well, while accepting that whether the action succeeds depends on factors, other people, chance, and circumstance, that lie outside their control.
This is not indifference or half-heartedness. The Stoic archer, in a classic image, takes careful aim and releases the arrow with full skill. But once the arrow leaves the bow, wind and the target's movement are no longer theirs to govern. They judge themselves by the quality of the shot, not by where the arrow lands.
Why it matters
How it works
Detachment from outcomes follows directly from the dichotomy of control. The practitioner asks, before any undertaking, which parts of this are mine and which are not. The intention, the preparation, and the effort are theirs; the outcome is, at best, a preferred indifferent, something it is reasonable to want but not to depend on.
With that distinction clear, a Stoic can pursue ambitious goals wholeheartedly. They set the goal, do everything in their power, and then receive the result, whether favorable or not, with equanimity. The work was the point; the outcome was always borrowed.