Abstract: This essay defends the following propositions. (1) It is pointless to object to choice architecture or nudging as such. Choice architecture cannot be avoided. Nature itself nudges; so does the weather; so do spontaneous orders and invisible hands. The private sector inevitably nudges, as does the government. It is reasonable to object to particular nudges, but not to nudging in general. (2) In this context, ethical abstractions (for example, about autonomy, dignity, and manipulation) can create serious confusion. To make progress, those abstractions must be brought into contact with concrete practices. Nudging and choice architecture take diverse forms, and the force of an ethical objection depends on the specific form. (3) If welfare is our guide, much nudging is actually required on ethical grounds. (4) If autonomy is our guide, much nudging is also required on ethical grounds. (5) Choice architecture should not, and need not, compromise either dignity or self-government, though imaginable forms could do both. (6) Some nudges are objectionable because the choice architect has illicit ends. When the ends are legitimate, and when nudges are fully transparent and subject to public scrutiny, a convincing ethical objection is less likely to be available. (7) There is, however, room for ethical objections in the case of well-motivated but manipulative interventions, certainly if people have not consented to them; such nudges can undermine autonomy and dignity. It follows that both the concept and the practice of manipulation deserve careful attention. The concept of manipulation has a core and a periphery; some interventions fit within the core, others within the periphery, and others outside of both.