The goal of my target essay is to articulate and recommend a view about what one is and is not committed to when one asserts that the domain of neuroscience or some other special science spans multiple levels of organization. How useful one finds my specific recommendation—that they be understood as levels of mechanisms— will depend on the uses for which one deploys the level metaphor. Martin raises a number of questions about my unpacking of the metaphor that help to clarify what is at stake in this discussion.