Evaluation is increasingly accepted as a tool for understanding and assessing the value of public programs and policies. Less understood, however, is how and why evaluation helps to inform judgments of value. This "American Journal of Evaluation" ("AJE") section on Professional Values and Ethics focuses on how values are to influence evaluation practice and on how one's understanding of valuing affects one's view of the ethics that should guide evaluators. In his invited contribution to this section, Ernie House addresses some of the gaps in the understanding of valuing with an essay on Daniel Kahneman's (2011) book "Thinking, Fast and Slow." House summarizes the book's account of the two cognitive capacities that humans bring to valuing and then develops the implications of these two approaches to valuing for the effective practice of evaluation. To introduce House's essay, the current article considers the issues that need to be addressed in valuing public programs and policies and explores the change in the charge for evaluators that comes from understanding two evolved capacities for assessing value.