For some reason, this quaint and rather mad book [The Mask of Sanity by Hervey Cleckley] continues to exert its hold on the imaginations of American psychiatrists.... The book's thesis... is that there is a kind of evildoer called a psychopath, who does not seem in any way abnormal or different from other people but in fact suffers from a 'grave psychiatric disorder,' whose chief symptom is the very appearance of normality by which the horror of his condition is obscured. For behind 'the mask of sanity' there is not a real human being but a mere simulacrum of one. Cleckley writes:

We are dealing here not with a complete man at all but with something that suggests a subtly constructed reflex machine which can mimic the human personality perfectly. This smoothly operating psychic apparatus not only reproduces consistently specimens of good human reasoning but also appropriate simulations of normal human emotion in response to nearly all the varied stimuli of life. So perfect is this reproduction of a whole and normal man that no one who examines him can point out in scientific or objective terms why he is not real. And yet one knows or feels he knows that reality, in the sense of full, healthy experiencing of life, is not here.

Cleckley's 'grave psychiatric disorder' is, of course, the same disorder that afflicted Count Dracula, Frankenstein's monster, and a host of other wonderful literary creations. The attempt to solve the problem of evil and perpetuate the Romantic myth of the innate goodness of man through the fanciful notion that the people who commit evil acts are lacking in the usual human equipment—are not real human beings at all but soulless monsters—is a familiar topos of Victorian Romantic literature. That Cleckley's book remains to this day a serious psychiatric text is a testament to the strength of this fantasy among psychiatrists. To McGinniss, the concept of the psychopath did not so much offer a solution to his literary problem of making MacDonald a believable murderer as given him permission to evade the problem—just as the concept itself evades the problem it purports to solve. To say that people who do bad things don't seem bad is to say something we all already know: no one flaunts bad behavior, everyone tries to hide it, every villain wears a mask of goodness. The concept of the psychopath is, in fact, an admission of failure to solve the mystery of evil—it is merely a restatement of the mystery—and only offers an escape valve for the the frustration felt by psychiatrists, social workers, and police officers, who daily encounter its force.

-- Janet Malcolm, The Journalist and the Murderer (Emphasis added)

This was published in 1989 and should have put to bed the question of "how could someone commit a mass shooting / sexually abuse children / do [insert other horrible thing] unless they were mentally ill?" Because most of the passage works just as well if you substitute broad, generic, vapid "mental illness" for psychopathy. Mass shootings, child abuse, sexual assault, violence and violation of others all exist because they're things human beings do. There is no special category of human beings or ready-to-dehumanize beings in whom responsibility for these acts can be quarantined. The only way to construct that category is tautological; a person is in it if and only if they have done such an act. There's no other test.

And yet, the question is not in bed, and continues to run around like a caffeinated toddler.

I, too, was invested in some idea of the innate goodness of human beings until not so long ago. But just as personal investment in the positive value of masculinity makes guys say inane things like "He's no man, he's a boy" in response to the violent and inane things other guys do, an investment in the positive value of humanity inevitably forces one to create dehumanizing categories in which to place one's fellow humans who are inconvenient counterexamples. If I can't invest in innate goodness without also investing in the absolute denial of human rights to certain categories of humans—categories which, as long as they exist, will expand to include everyone whose existence troubles anyone who has any power (also see: "groomer")—then I have to disinvest in innate goodness.