The Geography of Post-Truth World: An Introduction and Illustration: News reports suggest we live in a post-truth world in which expertise, fact, and reality are either discounted or dismissed. However, some of the issues that such a “post truth” world highlights are enduring classics of constant concern in the behavioral sciences. In this talk, I discuss specific implications of modern post-truth phenomena for science, education, and political life, describing how each talk in the series relates to them. I then illustrate post-truth issues by describing ongoing work in the lab asking who among political partisans is most likely to believe outlandish assertions about the other side–and whether these beliefs are authentic or mere posturing.