Why we may be inherently Bayesian deficient and how evolution may or may not have created an error in our way of thinking: It's been said that; "The essence of the Bayesian approach is to provide a mathematical rule explaining how you should change your existing beliefs in the light of new evidence". The bayesian approach is largely to consider all of the evidence as if you've seen it for the first time - disregarding any prejudices we may have had. Throughout our evolution our brains adapted to our environment, and arguably the most important thing in every human environment is other humans. Well, in this very complex environment, sometimes people throughout time have sought to discover other people's thoughts and feelings for political reasons such as alliances. The natural tendency, after discovering others thoughts and feelings (that don't agree with our own), is often to attempt to persuade others to our own way of thinking. We see this sometimes in our every day life - just turn on the news - it's so common to argue our own way of thinking in a persuasive manner, (and tune out others - i.e.talking over people and interrupting). The consequence is that we often fail to update our beliefs in the face of new information, and frequently find ourselves arguing things that we don't honestly believe ourselves. In order to maintain our own way of thinking, and to refrain from the significant social consequences of appearing wrong in public, we sometimes have developed a resistance to being swayed from our original thought process, and at the very least, often incorporating our own beliefs in what could be agreed upon in an argument -often improving our standing in a group. We see this even in our every day life all the time. We tune out the other person we are talking to and often just concentrate on converting them to our own views. If we hadn't developed this resistance to contrary views, we would have been too ineffectual at having people see things our way - "wining" arguments, and simply maintaining the same mind set. We could ill afford to be constantly changing our views in the human environment and we would be much less effective at converting others to our way of thinking. Might one possible example of this is be the refusal of some people to believe that global warming represents a very real threat to humanity in the face of overwhelming scientific evidence to the contrary?