Bayesianism, the doctrine that it's always rational to represent our beliefs in terms of probabilities, dominates the intellectual world, from decision theory to the philosophy of science. But does it make sense to quantify our beliefs about such ineffable things as scientific theories or the future? And what separates empty prophecy from legitimate prediction? David Deutsch is a British physicist at the University of Oxford, and is widely regarded as the father of quantum computing. He is the author of The Fabric of Reality (1997) and The Beginning of Infinity (2011). Full episode transcript available at:  See omnystudio.com/listener for privacy information.