The idea of “nudging” – presenting choices to people in a manner that biases their responses towards socially desirable results – is viewed by some as the basis of a new political theory of “libertarian paternalism”, while other have interpreted it as a more limited technique for achieving policy goals. This paper takes the latter view, suggesting that libertarian paternalism contributes little to normative theory in the abstract, while nudging does make two distinctive contributions to policy debates, although it also generate two specific ethical concerns. The first main virtue of nudging is that it calls attention to the cognitive “costs” of choice in a manner that can integrate with and inform conventional cost/benefit policy analysis. It thus enables a more accurate accounting of the tradeoffs involved in policy choices. The second virtue is that nudges introduce new policy options that can strike a better balance between competing ethical claims, even if the contours of the underlying ethical debates remain unchanged. Yet, nudging does generate two distinctive ethical questions. First, is there some general account of what constitutes impermissible manipulation? Second, by countenancing a greater range of behavioral interventions by the state, does nudging lower what James Q. Wilson called the “legitimacy barrier” in ways that are politically dangerous?