Although there has been considerable interest recently in statements that have been described as pragmatically inconsistent or self-defeating (for example, the statement ‘I do not exist’), the notion of pragmatic inconsistency has not been clearly defined and little attention has been paid to the relation between the assertion of these statements and the statements themselves. Hintikka [1] and Nakhnikian [2], for example mention that ‘I do not exist’ cannot be asserted without pragmatic inconsistency, but they are concerned mainly with belief statements that are pragmatically inconsistent rather than with the assertion of them. In doing so they have missed an important point—that it is the characteristics of statements that cannot be asserted without pragmatic inconsistency that render other statements pragmatically inconsistent.