 In Kant’s view, the candidates for explaining how this kind of unity comes to be, or, less ambitiously, for explaining my ability to recognize this sort of unity, are association and synthesis. At this point he appears to suppose that because Hume’s psychological theory has already been ruled out, synthesis is the only remaining option. So for me to represent the identity of the subject of different self-attributions, I must generate or at least recognize the right sort of unity among these representations, and synthesis must be invoked to account for this unity. Thus Kant contends that this combination “is an affair of the understanding alone, which itself is nothing but the faculty of combining a priori” (B134–5. Since the understanding provides concepts for synthesis, and because for synthesis to be a priori is, at least in part, for it to employ a priori concepts, Kant is contending here that synthesis by means of a priori concepts is required to account for the unity in question.