Dualisms

Dualisms are philosophical positions that hold reality consists of two fundamental kinds of something—substances, properties, or principles—that are distinct and not reducible to a single underlying reality. They are often discussed in contrast to monisms, which posit one basic kind of thing.

Substance dualism is the most widely cited form in Western philosophy. It argues that mind and body are two different substances: the mind is non-physical and conscious, while the body is physical and extended. The two interact, a claim that raises questions about causal connection and the nature of mental states. Descartes is a central figure in this tradition.

Property dualism, by contrast, holds that there is only one kind of substance (typically physical), but there exist non-physical mental properties alongside physical ones. In this view, mental states are real properties that cannot be fully reduced to physical properties, leading to debates about how such properties can causally interact with the physical world.

Religious and cultural forms of dualism place opposing forces or realms at the core of reality. Examples include cosmic dualisms such as good and evil in Zoroastrianism and Manichaeism, as well as dualist strands within Indian philosophy (dvaita), which maintain a fundamental distinction between the individual soul and a supreme divine principle.

Criticisms of dualism focus on the interaction problem—how two distinct substances or realms can causally influence each other—and on empirical challenges from neuroscience. Today, many philosophers favor physicalist or monist accounts, though dualistic theories persist in certain areas of the philosophy of mind and in religious thought.