Bill Radke talks with professor Philip Fernbach, co-author of the new book "The Knowledge Illusion ," about how people don't know nearly as much as they claim, whether it's about politics, science or even how a toilet works. Fernbach has found that we as a species share knowledge, which both helps society as well as gives us a self-inflated sense of how much we actually know. This is one reason, he says, that we may want to be a little more humble next time we think about starting an argument