The challenge to objective values › The argument from relativity

Mackie's first major argument begins from variation between moral codes and ways of life (chapter 1, section 8). He asks how that variation is best explained. His answer gives an important role to social conditions and the activities in which people participate.

The argument does not have the form: people disagree, therefore there is no truth. Disagreement also occurs about matters with objective answers. Mackie explicitly considers the possibility that moral disagreement reflects incomplete knowledge or different circumstances.

His stronger claim is explanatory. He thinks differences in ways of life help explain differences in moral codes better than a story in which communities imperfectly perceive one independent order of value. On his account, people may endorse certain standards because of the social activities they have learned to take part in.

As an original illustration, imagine two communities with different expectations about obligations to extended family. Their economic arrangements and patterns of dependence might help explain why they disagree. This possibility would not establish that either community is correct or that neither has access to an objective truth. It identifies the sort of explanatory alternative Mackie's argument requires us to consider.

A defender of objectivity can respond that the same underlying principle produces different judgments under different conditions. Mackie recognizes this route. The dispute then concerns whether those general principles are themselves best understood as responses to objective requirements, or as patterns of valuing shaped by human life.

To assess the argument, we therefore need more than a list of striking disagreements. We need to compare explanations, distinguish different factual circumstances from different evaluative commitments, and ask what each account can explain. Mere persistence of disagreement cannot carry all that work.