http://www.scientificamerican.com/article/unveiling-the-real-evil-genius/

Aha! See, this makes so much more sense to me than the more accepted trope of the analytical, scheming genius, if only because it only covers one personality. But the ability to rationalize what you’re doing, even if it’s wrong? That’s rampant in basically everyone.

Take procrastination for example. How many times have you thought or heard someone say “Oh, I procrastinate because I work better under pressure” or something similar? With that phrase, you’ve taken something that negatively impacts your productivity and told yourself that it’s a positive thing regardless of whether or not it’s true. That’s what being able to rationalize entails. People convince themselves with stories everyday that the guy in front of them meant specifically to cut them off, that the person at the register really does enjoy talking to you about your cats, that your significant other being quiet means they’re upset and haven’t voiced it yet. People good at these stories simply don’t recognize their evil as evil, because it’s so banal (Banality of Evil, people.)

It’s very easy to think that dishonesty is only a function of the individual, but the reality is that the environment plays a big role. You cheat when the rules are flexible or not very clear and when you have a conflict of interest or a reason to have a biased perception of reality.

We see this in many psychological studies, including the infamous Stanford Prison Experiment where flexibility or a specific point of view changes a person’s take on ethical and moral behavior. And the people studied don’t come in with a plan of action to cause harm to others; they’re just adept and creative enough to convince themselves that harm isn’t what they’re doing.