James Franklin was a professor of mathematics at UNSW when he began teaching ethics to maths students in the first course of its kind in the world. He differed from many academics offering professional ethics courses in being a philosopher (and a historian, but jokes about him being a polymath must have worn very thin by now). Franklin has been defending realist metaphysics for many years, mainly in the philosophy of science and the philosophy of mathematics. In this latest book, he sets out a strong realist case for the foundation of ethics. His very first sentence, “Ethics is not…