“When you think about these differences between the morality of one people and another, do you think that the morality of one people is ever better or worse than that of another? Have any of the changes been improvements? If not, then of course there could never be any moral progress. Progress means not just changing, but changing for the better. If no set of moral ideas were truer or better than any other, there would be no sense in preferring civilised morality to savage morality, or Christian morality to Nazi morality.
In fact, of course, we all do believe that some moralities are better than others. We do believe that some of the people who tried to change the moral ideas of their own age were what we would call Reformers or Pioneers—people who understood morality better than their neighbours did.”