David Lyons has pointed out that there are two kinds of relativistic theories:

• Theories that insist that an action can only be judged by the standards of the group to which the actor belongs. He calls this "agent's group relativism."
• Theories that insist that an action can only be judged by the standard's of the appraiser's group. He calls this "appraiser's-group relativism."

Lyons believes that the anthropologists who promoted cultural relativism tended toward agent's group relativism. On this view, we would not be allowed to judge other groups by our standards.

But we could also construct a relativistic theory of the second sort. This would still fit professor Sidgwick's definition of relativism, but would allow us to judge others who were outside our group.