Frank Jackson is Emeritus Professor at the Australian National University. He is best known for the knowledge argument and Mary’s Room—its accompanying thought experiment—but has published widely in the philosophy of mind, epistemology, metaphysics, and the philosophy of language. Graham Priest is a Distinguished Professor in the philosophy department at the CUNY Graduate Center. Like Frank, he is one of the most influential philosophers of the past fifty years, and has done important work on a wide range of topics, ranging from the philosophy of mathematics to logic and eastern philosophy. In this episode, Robinson, Frank, and Graham talk about David Lewis and his immense legacy in the philosophical world. They cover his character—Frank and Graham were friends with him for many years—as well as some of his work, ranging from the thesis of modal realism to Humean supervenience and the philosophy of set theory.