Abstract
Materialism, epiphenomenalism, dualism, idealism, and dual-aspect theories may all be represented by an appealing abstract mathematical device called a commutative diagram. Properties of the components of such diagrams characterize and, to some extent, even parameterize these systems and attendan metaphysical concepts (such as causal closure and supervenience) in a unified framework; process thought is of particular interest in this connection. In many cases we can even exemplify the theories typified by these diagrams in explicit graphical modeh. All of this tends to clarify the relationships among key philosophical positions and to sharpen our sense of the effective domain and principa limitations of each. Systematic variation of these abstract diagrams may even suggest cogent metaphysical systems yet to be examined.