The mind-body problem, which Schopenhauer called the ""world-knot,"" has been a central problem for philosophy since the time of Descartes. Among realists--those who accept the reality of the physical world--the two dominant approaches have been dualism and materialism, but there is a growing consensus that, if we are ever to understand how mind and body are related, a radically new approach is required. David Ray Griffin develops a third form of...