Given the accelerating pace of information available in today’s world, our ability to be able to reflect critically on this information is more important today than ever before; but with the growth of social media and its unfortunate consequences – “fake news,” “post-truth,” and “truth decay” – critical reflection has become harder and harder to do. This apparent paradox, why “facts” and “evidence” seem to have so little effect on rational behavior, is explored, along with the research evidence on the self-reinforcing nature of confirmation bias and its sequelae, belief persistence, polarization, and tribalism.