This episode turns to Christine Korsgaard's Tanner lectures, "The Sources of Normativity," to explore how morality might be rationally vindicated from within the nature of practical rationality. Korsgaard's project is an iteration of the Enlightenment's attempt to ground morality in human nature. Korsgaard suggests that the correct moral theory will not merely provide an explanation of our moral natures, but also be justified in the light of our status as reflective animals. Her constructivist account of normativity will conceive of obligations as integral to our sense of identity, which in turn depends on our status as deliberative agents who must act upon some principle. Is the source of normativity a product of the correct application of moral concepts to the sphere of action?  Are values the product of our self-legislating will? Can we understand unconditional obligations as derived from our shared identity as human beings?