Many philosophical theories of self-knowledge can be understood as attempts to explain why self-ascriptions enjoy a certain kind of authority that other-ascriptions lack (the Authority Thesis). The aim of this paper is not to expand the stock of existing explanations but to ask whether the Authority Thesis can be adequately specified. To this end, I identify three requirements that must be met by any satisfactory specification. I conclude that the search for an adequate specification of the Authority Thesis leads to (...) a dilemma: it either yields an interpretation under which the thesis is philosophically interesting but false, or it produces an interpretation under which the thesis is actually true but of minor philosophical interest. (shrink)