Tamar Gendler closes out Yale's Philosophy and the Science of Human Nature course by pulling together threads from across the semester. She opens with remarks on the course's method for reading and presenting philosophical and empirical articles, then turns to Cass Sunstein's work on social norms, focusing on his willingness to pay versus willingness to accept distinction. Gendler applies that heuristic-reasoning framework to explain why people respond to the trolley problem the way they do, treating it as a case study in how cognitive shortcuts shape moral judgment. The lecture ends with a systematic comparison of the political philosophies of Thomas Hobbes, John Rawls, and Robert Nozick, mapping out where their accounts of human nature and justice converge and diverge. Recorded in Spring 2011 as the final lecture of the course, it works as a synthesis of the semester's recurring questions about rationality, ethics, and political theory.