Richard Thaler and Cass Sunstein's Nudge advances a theory of how designers can improve decision-making in various situations where people have to make choices. We claim that the moral acceptability of nudges hinges in part on whether they can provide an account of the competence required to offer nudges, an account that would serve to warrant our general trust in choice architects. What needs to be considered, on a methodological level, is whether they have clarified the competence required for choice architects to prompt subtly our behaviour toward making choices that are in our best interest from our own perspectives. We argue that, among other features, an account of the competence required to offer nudges would have to clarify why it is reasonable to expect that choice architects can understand the constraints imposed by semantic variance. Semantic variance refers to the diverse perceptions of meaning, tied to differences in identity and context, that influence how users interpret nudges. We conclude by suggesting that choice architects can grasp semantic variance if Thaler and Sunstein's approach to design is compatible with insights about meaning expressed in science and technology studies and the philosophy of technology.