To inhibit you from seeing yourself as a buffoon

"Cognitive biases are predicable patterns of thought and behavior that lead you to draw incorrect conclusions. You and everyone else come into the world preloaded with these pesky and completely wrong ways of seeing things, and you rarely notice them. Many of them serve to keep you confident in your own perceptions or to inhibit you from seeing yourself as a buffoon. The maintenance of a positive self-image seems to be so important to the human mind you have evolved mental mechanisms designed to make you feel awesome about yourself."