  While each of these theorists highlights disagreement, it seems that disagreement is only part of what generates the argument for noncognitivism.  On one reading, Gibbard’s argument seems to tacitly involve one of the assumptions that makes the Open Question Argument seem compelling – that property identities are fully transparent to competent thinkers.  Our confidence that the dispute over what is rational in the prisoner’s dilemma dispute is not over a descriptive fact seems rooted in the stipulation that all the descriptive facts are clear to both thinkers.  But that stipulation only settles the matter if we further assume that the identity of rationality and the property picked out the the relevant description (if indeed there is such and identity) will be transparent to the parties to the dispute.  So this reading of Gibbard’s argument will have it stand or fall with the Open Question Argument. 