The characteristic asymmetry in intentionality attributions that is known as the Knobe effect can be explained by conjoining an orthodox theory of intentional action with a normative account of intentional omission. On the latter view: omissions presuppose some normative context; there are good reasons why the intentionality of omissions requires agents' knowledge rather than intention. The asymmetry in intentionality attributions in Knobe's cases can be seen to be derivative from an asymmetry in intentional omissions. The omissions account further explains the (...) Butler problem and some related puzzles. It also safeguards the simple view of intentional action from the asymmetry challenge. (shrink)