Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 103-109).This dissertation is about whether and how non-representational attitudes could play a role in our theories of rationality. In Chapter 1 ('Negation, expressivism, and intentionality') I argue that the best explanation for why two mental states are inconsistent need not presuppose that such states are representational-that they have, in the jargon, truth-conditions. I use this to provide a solution to the 'negation problem' for metaethical expressivism. In Chapter 2 ('Structuring logical space') I sketch an account of mathematical practice along non-representat...