Sen. Bernie Sanders (I-Vt.) is doing well, if not good, by reducing the debate about equality to resentment of large fortunes. He should read Harry G. Frankfurt’s new book “On Inequality.” It is so short (89 pages) that even a peripatetic candidate can read it, and so lucid that he cannot miss its inconvenient point: “It is misguided to endorse economic egalitarianism as an authentic moral ideal.”

Frankfurt, a Princeton professor of philosophy emeritus, argues that economic inequality is not inherently morally objectionable. “To the extent that it is truly undesirable, it is on account of its almost irresistible tendency to generate unacceptable inequalities of other kinds.” These can include access to elite education, political influence and other nontrivial matters. But Frankfurt’s alternative to economic egalitarianism is the “doctrine of sufficiency,” which is that the moral imperative should be that everyone have enough .

The pursuit of increased economic equality might, but need not, serve the ethic of sufficiency. And this pursuit might distract people from understanding, and finding satisfaction with, “what is needed for the kind of life a person would most sensibly and appropriately seek.” This has nothing to do with “the quantity of money that other people happen to have.” Frankfurt argues that “doing worse than others does not entail doing badly.” And an obsession with others’ resources “contributes to the moral disorientation and shallowness of our time.”