However evil you believe the Nazis were, the reality was worse. When the crematoriums at Auschwitz could not keep up with the gas chambers, they began burning corpses in open pits. To keep the pits going, fuel had to be added at regular intervals. An ordinary evil person would pour, say, gasoline onto the fires. The Nazis used liquified human fat, collected from the bodies in the pits themselves.
The nature of evil is a philosophical problem, and what have we come up with? Luke Russell, in Evil: A Very Short Introduction, says an act is evil if it is “extremely harmful for at least one” victim, and a person is evil if he is disposed to perform evil acts. On this view, evil stands to harm, as hot—or scorching—stands to warm. But this can’t be correct, can it? Evil acts don’t just have more of what makes something wrong, they have something extra, right? (Daniel Haybron: “we cannot get from bad to evil by adding any number of ‘verys’”.)
Russell’s theory of evil uses a thin moral range—harm is the central concept—but his discussions of evil use stronger stuff: those who perpetrate evil are moral monsters; they are morally depraved. This list could be extended: being depraved exists in a circle of similar notions, like being perverted, or corrupted. Russell also says that we are rightly horrified by evil. This is easily explained, by the fact that monsters are horrifying—thus their frequent appearances in horror movies. Of course evil does not inspire the same horror as a viewing of Alien: horror comes in many forms. Horror is an intense dread or dismay, and is an apt response to any “monster,” that is, something so deformed as to be alien, or almost so. Since evil is moral monstrosity, it is apt to cause a specifically moral kind of horror.
In any regard, since one could be disposed to perform extremely harmful acts, without being monstrous or depraved—the disposition could have some other ground—Russell’s theory is false.
Other theories try to do more justice to these features of evil, while still corralling evil in the dry idiom of analytic philosophy.