Abstract:  I present an argument against moral relativism.  My argument
proceeds in three steps.  First, since there are many views that go by the
name of moral relativism, I begin by identifying my target.  I argue that
moral relativism is a realist, cognitivist, and naturalist metaethical view.
Second, I spend some time clarifying how an argument against this view can
be constructed.  Because standard defenses of moral relativism are an
admixture of conceptual and empirical claims (concerning, typically, alleged
facts about moral diversity and disagreement), sorting out what can count as
admissible evidence and support against relativism is actually a complex
task.  Third, I lay out my argument.  I show an example of a moral norm that
applies to all moral agents.  I present and interpret the evidence for this
norm, and then I explain how it can be used to build an argument against
moral relativism.  I conclude by defending my argument from some possible
objections.