In this thesis I consider the problem of the distinctiveness of knowledge of our own mental states and attitudes. I consider four influential approaches to this problem: the epistemic approach, the "no reasons view," the neo-expressivist approach and the rational agency approach. I argue that all of them face serious problems. I further argue that many of these problems are connected with the lack of fine-grained enough classification of the entities with respect to which we have self-knowledge. I suggest such a classification, distinguishing passive occurrent mental states, mental actions and standing attitudes, and argue that we should treat each of these categories separately for the purpose of explaining self-knowledge of them. I discuss in detail self-knowledge we have with respect to two of these categories: standing attitudes and mental actions. On my account self-knowledge of standing attitudes stands in a derivative relation to self-knowledge of other kinds. In my discussion of self-knowledge of mental actions I establish that we have a distinctive non-observational kind of self-knowledge and show some specific characteristics of this kind of self-knowledge. In the end I attempt to relate self-knowledge of mental actions to practical knowledge in the ordinary sense of skill.

Decisions are performatives - or at least, they share important features with performative utterances that can elucidate our theory of what type of thought they are, and what they do. Namely, decisions have an analogous force to that of performatives, where the force of a propositional attitude or utterance is constituted by (i) its point, or purpose, which is mainly a matter of its direction-of-fit, and (ii) its felicity conditions. The force of both decisions and performatives is to bring into being the states of affairs represented in their intentional contents, merely in virtue of the decision or performative’s occurrence and the satisfaction of the felicity conditions they presuppose. The first chapter of the thesis explicates this general framework, and the second and third attempt to show some of the work it can do for a theory of decisions.