What is the source of morality? Can science provide us with morality—or are religious principles required? Steven Pinker, Johnstone Family Professor of Psychology at Harvard University and best-selling author, engages in a dialogue on the human brain's capacity for making moral decisions with Dr. William Hurlbut, prominent bioethicist and Consulting Professor in the Neuroscience Institute at Stanford University. Speaking as scientists and as individuals—one an atheist, the other a Christian—they explore what science tell us about free choice and how this impacts their views on morality. Q&A is moderated by Troy Van Voorhis, Associate Professor of Chemistry at MIT.