 Suppose, then, that the ideal observer theorist decides that the definition of the ideal observer must include more than the bare idea of impartiality – that in addition the observer must be, say, compassionate (and thus not indifferent); and that she must possess a considerable facility for proper moral judgments – practical wisdom, in the Aristotelian sense. Such a theorist will now face a different problem: the more we build into the definition of our ideal observer, the less useful it becomes as a heuristic device. Stipulating that the ideal observer is very wise, for example, is not very helpful if we ourselves are not wise, and so have no idea what an ideally wise observer would choose. Indeed, ideal observer analyses that go too far in this direction seem to become circular – the ‘ideal’ observer is ideal because she always makes proper judgments, those being defined as just those judgments the ideal observer would make (Broad 1959, 263). A circularity of this sort seems to be present in John Stuart Mill’s claim: