This paper aims to clarify the status of capability in Sen's idea of justice. Sen's name is so widely associated with the concept of capability that commentators often assume that his contribution to the study of justice amounts to a capability theory, albeit underdeveloped. We argue that such a reading is misleading. Taking Sen's reticence about operationalization seriously, we show that his contribution is inconsistent with a capability theory. Instead, we defend the idea that the capability approach plays a heuristic role: capability is a step in his argument against alternative materials, but is not meant as a definitive end. Sen defends a critical perspective primarily to encourage public reasoning and respect for agency as regards the definition of what should count in the evaluation of social states.