In northwest Alaska, kunlangeta "might be applied to a man who, for example, repeatedly lies and cheats and steals things and does not go hunting, and, when the other men are out of the village, takes sexual advantage of many women." The Inuits tacitly assume that kunlangeta is irremediable. And so, according to Murphy, the traditional Inuit approach to such a man was to insist he go hunting, and then, in the absence of witnesses, push him off the edge of the ice.

The physical basis for sociopathy is approximately 50 percent inheritable, which sounds more dramatic than it probably is, because most personality characteristics that psychologists test for and study the genetics of are about 50 percent inheritable. Introversion, extroversion, it turns out that they're about 50 percent inheritable, which means that somehow sociopathy is physical, it's organic.

The perfect victim, from the sociopath's point of view, is the person who is smart enough and capable enough to do him some good in the world and who is also fun to manipulate. How much fun is it to manipulate someone who is stupid and incompetent?

An intelligent sociopath can learn the rules about what's good and what's bad, what people see as good and bad. But they don't get that intervening sense of guilt, that pang of conscience, on account of it. So they tend to know what's wrong or right, they just don't care. That's another thing that they can use against us: that we do care. We're predictable in that.

In Western culture, particularly North America, a lot of rules are descriptors for sociopathy: a general acceptance of lying as long as you win, an attitude of "me first," an attitude that what it looks like is more important than what it is. This makes it much easier for a sociopath to be camouflaged in our culture.

I was once doing a book signing and a man came up to me and said that he gave classes to people who'd been convicted of drunken driving twice. He said he felt that nearly all of those people were what I was describing as sociopathic. Which makes a great deal of sense to me. We always talk about how could you possibly, knowing that you're drunk, get behind the wheel of a car again and do that? Well, you could if you didn't give a half a damn what happened.

The sociopath wants the person to be easily enough fooled to stick with him. This can be accomplished by looking for someone who is very, very loyal. Most of us consider loyalty to be a very positive trait - and it is a positive trait. But it also blinds people to some of the traits of the person they're loyal to.