W hat is the psychology of economic decision making? Prevailing answers to that question have focused on the extent to which human decisions are flawed and irrational. We will suggest instead that many common biases and heuristics reflect a deeper adaptive rationality. We will further suggest that, instead of a single human mind constrained by a single set of biases and striving toward a monolithic goal of utility maximization, our brains contain several distinct subselves, each with a different set of priorities and each pursuing a different set of utility functions. We also consider a number of testable hypotheses that flow from this perspective.