In Presumptive Meanings: The Theory of Conversational Implicature, Levinson (2000) argues that in historical as well as synchronic work there is need to distinguish three types of pragmatic principles, which he labels the Q-, M-, and I- “heuristics”. This is in contrast to Horn (1984), who argues for two types of “principles”: Q- and R-. In the present paper, it is argued that the proposed distinction between Q- and M- Heuristics is not necessary or consistently maintainable.