How is it possible to murder a million people one by one? Hatred, fear, madness of one or many people cannot explain it. No one can be so possessed for the months, even years, required for genocides, slavery, deadly economic exploitation, sexual trafficking of children. In The Evil of Banality, Elizabeth Minnich argues for a tragic yet hopeful explanation. "Extensive evil," her term for systematic horrific harm-doing, is actually carried out, not...