The nature of contingency : quantum physics as modal realism This book defends a radical new theory of contingency as a physical phenomenon. Drawing on the many worlds approach to quantum theory and cutting edge metaphysics and philosophy of science it argues that quantum theories are best understood as telling us about the space of genuine possibilities rather than as telling us solely about actuality. When quantum physics is taken seriously in the way first proposed by Hugh Everett III it provides the resources for a new systematic metaphysical framework encompassing possibility necessity actuality chance counterfactuals and a host of related modal notions. 0Rationalist metaphysicians argue that the metaphysics of modality is strictly prior to any scientific investigation; metaphysics establishes which worlds are possible and physics merely checks which of these worlds is actual. Naturalistic metaphysicians respond that science may discover new possibilities and new impossibilities. This books quantum theory of contingency takes naturalistic metaphysics one step further allowing that science may discover what it is to be possible. As electromagnetism revealed the nature of light as acoustics revealed the nature of sound as statistical mechanics revealed the nature of heat so quantum physics reveals the nature of contingency