David Langlois is a PhD candidate in the Department of Philosophy. He has research interests in normative ethics, practical reason and rationality. His dissertation investigates the relationship between the requirements of rationality (such as the requirement to take the means to one's ends) and other normative requirements (such as the requirements of morality). He has a BA and an MA in Philosophy from Queen's University in Canada. While at Harvard, he has served as a teaching fellow for classes on moral theory, political philosophy, epistemology, and the requirements of rationality.