I recently read (okay, I actually listened to the audio book) "Stumbling on Happiness" by Daniel Gilbert, which takes a look at why humans are not very good at accurately remembering the past or envisioning the future — among other things. One of the major points in the book is that we have developed methods of self-deception to help us cope with major traumas. Just think about how many times you've heard someone say that getting a divorce, the death of a loved one, or tragic accident were really 'the best thing that has ever happened' to them. As soon as we go through a traumatic experience, our brain starts to find ways to look at it in a positive light. 'She was never right for me', or 'It made me look at life in a fresh way'. I also ran across a video (thanks to seed) discussing Robert Trivers's views of self-deception, particularly the fact that it is easier to deceive others if you first deceive yourself. For instance, you're more likely to intimidate someone if you act like you can win a fight against them, and you're better able to act like you can win if you have deceived yourself into believing you can win, whether or not it is actually true. This made me think about something I've read before, that depressed people make more realistic predictions about the world than the rest of us. I'm not sure what study that originally came from, but I'm pretty sure it was mentioned by Steven Levitt in Freakanomics. It made me think that maybe depression is simply an inability to deceive yourself very well.