Suppose that Robinson Crusoe’s ideology teaches that native islanders like Friday are unable to farm. It flatters his pride to believe that only Europeans can understand agriculture. If Crusoe’s belief is in fact correct, he wisely specializes in agriculture and has Friday do other kinds of work. But if Crusoe’s belief is blind prejudice, keeping Friday out of agriculture reduces total production and makes both men poorer. The difference between Crusoe’s potential living standard and his actual living standard is the full price of his ideological stance.
