Experts from different fields argue that there are good reasons to believe in the existence of the soul as distinct from the physical body. What do we mean when we speak about the soul? What are the arguments for the existence of the soul as distinct from the physical body? Do animals have souls? What is the difference between the mind and the soul? "The Soul Hypothesis" brings together experts from philosophy, linguistics and science to discuss the validity of these questions in the modern world. They contend that there is an aspect of the nature of human beings that is not reducible to the matter that makes up our bodies. This perspective is part of a family of views traditionally classified in philosophy as substance dualism, and has something serious in common with the ubiquitous human belief in the soul. "The Soul Hypothesis" presents views from a range of sciences and the resulting big picture shows, more clearly than one author could with one area of expertise, that there is room for a soul hypothesis.