Last night I saw a few tweets from people I respect noting that in coming days, NSA whistleblower Edward Snowden may not look as noble as we now think him. (I hope I'm wrong, one added.) In some ways, this seems inevitable. Whistleblowers are almost definitionally not normal people. When the spotlight shines on their lives, the glare makes every irregularity evident.

What whistleblowers do is usually moral. A free society depends on people who are willing to go public when they see wrongdoing. But there are good reasons that whistleblowing behavior is actually pretty rare.

When you read that, you're probably thinking of the financial dangers, and you're not wrong. Most people who blow the whistle on an employer end up losing their jobs. I don't know how much Edward Snowden has managed to save on his reported $200,000 annual salary, but it's unlikely to be enough to live on for the rest of his life. Yet even those who admire him may have second thoughts about hiring him. If he will betray one employer . . .

Human institutions, from the family to the government, are founded by trust. You need to be able to trust the people you work with, at least to the extent of being able to predict their future behavior. You may think you don't trust that rat down the hall, but in fact, you do trust him quite a lot: not to come into work with a machete and hack you to death in order to secure your superior office chair, not to start randomly swearing at clients, and so forth.

Some of that trust is enforced by fear of the consequences. But a lot of our ability to make a credible committment to be trustworthy comes from the fact that we are hard wired to be loyal. Imagine trash talking your family, your employer, or your country on national television--in a language that none of them speaks. In other words, imagine being disloyal in a way that was not detectable by the people you were betraying. You probably still wouldn't do it anyway, would you? It feels wrong. You would feel bad about yourself if you did it.

That's why psychopaths are so dangerous: they don't have any of the internal brakes, the shame and guilt, that keep the rest of us from blatantly violating the trust of people around us. Oh, of course we do betray people from time to time--we break promises, forget to call our grandmothers, and engage in the guilty pleasure of gossiping about friends. But the hallmark of these betrayals is that they are impulsive and unjustified. Psychopaths feel no guilt about doing these things--or stealing your money, your wife, and your dog. They are fundamentally untrustworthy, though also, thankfully rare.

Whistleblowers are not psychopaths; psychopaths are too self-interested to risk all to right a wrong. But they are weird in their own way, because they have to be in order to be willing to violate the trust of their group in order to protect a principle. In Eyal Press' book on dissenters, Beautiful Souls, they come off as rigid, idealistic, a bit self-righteous, and more than a little naive. Those are not characteristics that make you fit in.

So in coming days we will almost certainly realize that Edward Snowden is not like the rest of us. In fact, the details of his resume already released hint as much: a high school dropout somehow turned intelligence worker, who kept his live-in girlfriend in the dark about what he was doing and told her he was going on a business trip while he disappeared to Hong Kong. That's a hell of a way to break up with someone. This detail didn't attract a huge amount of attention admidst all the other surprise revelations that came out over the weekend, but I found it quite striking. As one of my friends noted, if a live-in boyfriend had done this to me, he'd have more than the CIA to worry about.

We may well end up grateful to Edward Snowden, and also find that we don't like him very much. Of course, Edward Snowden probably doesn't care. After all, if he cared about people liking him as much as the rest of us do, he probably wouldn't have been able to do with he did.