Propositional attitudes and their contents in the midst of the de se

This thesis develops an account of propositional attitudes and their contents that accommodates the purportedly distinctive features of de se attitudes (i.e., the first-person thoughts) and contents, thereby elucidating the scope of indexicality and context-sensitivity both in natural languages and human mind. To achieve this, I introduce two novel semantic primitives, almost-impossible and almost-necessary propositions, within the framework of a modified Lewisian-centered content and attitude semantics. This modification, which relies on these novel semantic primitives, remains compatible with the metaphysical foundations of Lewisian counterpart-theoretic semantics for quantified modal logic. The efficacy of this account is subsequently evaluated by addressing the problem of communication in de se thought, specifically the communication of first-person or self-locating thoughts across conversational participants.