HUMAN beings have an appetite for moral outrage. You see this in public life — in the condemnation of Donald J. Trump for vowing to bar Muslims from the United States, or of Hillary Clinton for her close involvement with Wall Street, to pick two ready examples — and you see this in personal life, where we criticize friends, colleagues and neighbors who behave badly.
Why do we get so mad, even when the offense in question does not concern us directly? The answer seems obvious: We denounce wrongdoers because we value fairness and justice, because we want the world to be a better place. Our indignation appears selfless in nature.
