Mill highlights what he considers to be an ironic or paradoxical aspect of common attitudes regarding morality, which is that people are more invested in rules or principles than in the higher values that supposedly animate those rules. He writes that people tend to follow “customary morality,” which they have learned through either education or common opinion. While they think of the moral rules that they live by as “obligatory,” they cannot truly name the underlying moral principle:
[When] a person is asked to believe that this morality derives its obligation from some general principle round which custom has not thrown the same halo, the assertion is to him a paradox; the supposed corollaries seem to have a more binding force than the original theorem; the superstructure seems to stand better without than with what is represented as its foundation. He says to himself, I feel that I am bound not to rob or murder, betray or deceive; but why am I bound to promote the general happiness?
Though people might feel obliged to follow certain rules, they care more about the rule than any “general principle” of morality. Mill identifies this as a paradox. For him, there is a clear irony in the fact that a person feels more “binding force” to obey some specific rule or custom than they do “the original theorem” that provides its rationale. This state of confusion is, for Mill, like imagining that a house looks stronger without its foundation. Mill mocks a hypothetical person who closely follows the rules not to “rob or murder” another person, but who feels no compulsion to “promote the general happiness.”