  Theorists sometimes present the motivations for noncognitivism as rooted in the distinctive nature of moral disagreement.  For example, Gibbard (1990) begins with a puzzle about how (for instance) two people who both fully understand the prisoner’s dilemma scenario can still disagree over what it is rational for someone in such a situation to do.  It doesn’t seem that they are asking after the meaning of the word ‘rational’ yet there also doesn’t seem to be any descriptive fact over which they disagree.  And Stevenson (1944) begins his book by distinguishing the kind of disagreement in play when two people disagree in their ordinary beliefs from “disagreements in attitude” which involve conative clash.  Having made the distinction he suggests that moral disagreements involve both, and then uses that diagnosis to motivate his own noncognitivism as developed in the rest of the book.  