Numerous studies have shown that people are over-confident in their own abilities. Most people, for example, think that they are better drivers than average.
This doesn't make any sense because surely the best way to optimize whatever you're trying to accomplish in life is by having a very accurate idea of your own abilities.
Moreover, people in general think that they are more trustworthy and behave more honorably than others, which is why there are so many disputes in which each side thinks it is right.
Again, this just doesn't make sense.
So why do people over-estimate their own abilities and think they are better people than average?
To answer this question, we need to recall that people are social creatures. In order for them to maximize their survival and mating opportunities, they need to convince others that they are strong, competent, honorable people who would be good mates or good colleagues.
To do this, it makes sense to deceive others about who one is, by making others think you are more competent and more trustworthy than you actually are. That way, a man might convince a women to mate with him, a woman whom he would not otherwise attract if she knew the truth. Or a man might convince an adversary not to attack him by deceiving the adversary into thinking he is stronger than he actually is.
People deceive others in order to maximize reproductive potential. So, humans have evolved deceiving one another. As a result, they have developed a fine sense for spotting deception. For example, noticing if someone is shaking or sweating or smiling oddly.
A surefire way to counter this deception-spotting skill is to actually deceive yourself, so you don't think that your are lying when you pretend to be a better mate or more formidable adversary than you actually are. If you actually believe you are better than you are, then you will not show signs of deception.
The upshot of all this is that in order to maximize reproductive potential, people actually believe themselves to be stronger, more competent, more honorable, and more trustworthy than they in fact are.
So, the moral of the story is to drive more carefully than you think necessary. Another is to think twice before mating with a self-confident male.
- Robert Trivers, "Deceit and Self-Deception"