I view rationality as a tool that we primates have developed to try to apprehend the world as it really is. There are lots of aspects of primate psychology that pull us away from rationality, and there are other primates who, for the same reasons, would take advantage of our chimpanzee nature for their own benefit, or to satisfy needs that even they don't understand. But reality is still out there, and kidding ourselves like King Canute isn't going to make our lives better.