They blame “mental illness” for the same reason they blame “evil” when talking about such shootings: They want to portray the image of powerlessness, to say that there’s “nothing that can be done” to absolve themselves of any responsibility for such acts. When it’s “gang violence” or “terrorism,” they’re off to the races with ideas about how they can stop such and protect us from “those people.” But when it’s a white guy in the grip of “mental illness” or motivated by “evil,” all they can do is throw up their hands and moan that there’s just nothing they can do to stop such acts.