This essay has three general themes. The first involves the claim that nudging threatens human agency. My basic response is that human agency is fully retained (because nudges do not compromise freedom of choice) and that agency is always exercised in the context of some kind of choice architecture. The second theme involves the importance of having a sufficiently capacious sense of the category of nudges, and a full appreciation of the differences among them. Some nudges either enlist or combat (...) behavioral biases but others do not, and even among those that do enlist or combat such biases, there are significant differences. The third general theme is the need to bring various concerns (including ethical ones) in close contact with particular examples. A legitimate point about default rules may not apply to warnings or reminders. An ethical objection to the use of social norms may not apply to information disclosure. Here as elsewhere, abstraction can be a trap. We continue to learn about the relevant ethical issues, about likely public reactions to nudging, and about differences across cultures and nations. Future progress will depend on a high level of concreteness, perhaps especially in dealing with the vexing problem of time-inconsistency. (shrink)