Relativism and disagreement

The relativist's central objection to contextualism is that it fails to account for the disagreement we perceive in discourse about "subjective" matters, such as whether stewed prunes are delicious. If we are to adjudicate between contextualism and relativism, then, we must first get clear about what it is for two people to disagree. This question turns out to be surprisingly difficult to answer. A partial answer is given here; although it is incomplete, it does help shape what the relativist must say if she is to do better than the contextualist in securing genuine disagreement.