Thomas Cathcart and Daniel Klein have known each other since they were philosophy students at Harvard. They have written several bestsellers together, including Plato and a Platypus Walk into a Bar and Aristotle and an Aardvark Go to Washington. Tom is the author of The Trolley Problem, or Would You Throw the Fat Guy Off the Bridge? Danny's other books include Travels with Epicurus and Every Time I Find the Meaning of Life They Change It.