In this passage Immanuel Kant says “as a species.” But he goes on to ­discuss the individual human will and argues that for it there is no middle ground. I call this view Kant's “moral excluded middle.” Kant's view on this point is shared by many who hold that only those who are good deserve heaven and those who are evil deserve either purgatory or hell. The idea that human beings can eventually be sorted into those who deserve to go to heaven (people of good will) and those who deserve purgatory or hell (people who lack good will) presupposes that of those who are capable of morality, any who are not good are evil and that of those who are evil, some may be redeemable, but others are not. Kant rejects the idea of diabolical evil as inapplicable to human beings. But he accepts the idea that a will that is not good is evil. In this chapter, I disagree with Kant's moral excluded middle. But I defend a distinction between diabolical evil and lesser evils.

A widely shared common-sense view is that good and evil, unlike right and wrong, are not contradictories. They are contraries.