The human mind is both brilliant and pathetic. We have mastered fire and have stood on the moon, and yet every one of us is fundamentally ignorant, irrational and prone to making simple mistakes every day. In this groundbreaking book, cognitive scientists Steven Sloman and Philip Fernbach show how our success as a species is down to us living in a rich community of knowledge where we are drawing on information and expertise outside our heads. And we have no idea that we are even doing it. Utilising cutting-edge research, The Knowledge Illusion explains why we think we know more than we do, why beliefs are so hard to change and why we are so prone to make mistakes. Providing a blueprint for successful ways to work in collaboration to do amazing things, it reveals why the key to human intelligence lies in the way we think and work together.