Tamar Gendler, teaching Yale's Philosophy and the Science of Human Nature, examines Glaucon's challenge from Book II of Plato's Republic. Glaucon argues that Socrates must show justice is valuable in itself, not just for the reputation it brings, and illustrates the opposing view with the thought experiment of the Ring of Gyges, which grants its wearer invisibility and freedom from consequence. Gendler then turns to Daniel Batson's laboratory experiments on moral hypocrisy, which found that subjects often care more about appearing fair than about actually being fair, results she connects directly to Glaucon's hypothesis. The lecture moves from close reading of the Republic's opening argument into empirical psychology, asking whether real behavior backs up Plato's skeptic. A question and answer session follows, recorded as part of Gendler's Spring 2011 Yale course and made available through Open Yale Courses.