Andrew O'Hehir in Salon:
Much of the history of human thought has revolved around our efforts to understand the nature of evil, which have never yielded anything like a satisfactory result. We are fascinated by serial killers and murderous dictators, torn between the obvious fact that they are human beings like ourselves and the conviction that in some fundamental way they must be different. Fictional embodiments of evil, like J.R.R. Tolkien’s Sauron or J.K. Rowling’s Lord Voldemort, are essentially reassuring because they are nothing except evil; both are built on the Satanic pattern, meaning they were once pure, but have left their uncorrupted selves far behind. Even the perversely noble Satan of “Paradise Lost,” after nine days of torture by fire, knows only one purpose: “immortal hate” and “eternal War irreconcileable” against the power of heaven.
Set against this conception of inhuman monstrosity we have the countervailing evidence, famously marshaled by Hannah Arendt under the controversial term “the banality of evil.” In latter days, many scholars and Holocaust survivors have contended that Arendt misapplied this term to Adolf Eichmann. (Most notably, the late Benjamin Murmelstein, who knew Eichmann well, told “Shoah” director Claude Lanzmann that Eichmann was a sadist and a zealous anti-Semite.) But the dispute over Eichmann’s personality oversimplifies the profound philosophical insight that lies behind Arendt’s phrase, which speaks to the fact that people who do terrible things, and who hold beliefs most of us find noxious and inexplicable, often appear to be entirely normal in other areas of life.
More here.