In Seven Puzzles of Thought and How to Solve Them Sainsbury and Tye defend a version of originalism, the view that concepts are to be individuated by way of their origins. A consequence of their account is that concepts that are semantically distinct may nonetheless be of the same type (and vice versa). In this thesis I argue that a result of this commitment is that their account fails as a general theory of concepts and thoughts. I show by appeal to a thought experiment that Sainsbury and Tye s originalism cannot provide a general account of the cognitive role of concepts and thoughts: the theory fails to explain certain cases of rationality. Further, I show that originalism fails at the specific task of solving three classical puzzles within the philosophy of mind and language; puzzles the solution of which is the raison d'être of originalism.