Substantialists

Substantialists are philosophers who defend substance theory, the view that the basic entities of ontology are substances—persisting objects that bear properties. According to substantialism, ordinary objects such as a cat, a chair, or a person have an underlying substratum that provides unity and persistence through change; properties inhere in these substances rather than simply forming a bundle.

Historically, substance theory traces to Aristotle’s hylomorphic framework and to medieval scholastic metaphysics. It was developed and defended by early modern thinkers such as Descartes, Spinoza, and Leibniz, who argued for fundamental substances with essential natures. In the analytic tradition, contemporary defenders include philosophers like David Armstrong and E. J. Lowe, who argue that substances are necessary to account for persistence, causation, and the distinguishing of objects across possible worlds.

Key contrasts are with bundle theories, which treat objects as mere collections of properties with no underlying substratum. Substantialists confront questions about what counts as a substance, how substrata are individuated, and how they ground persistence and causation. Critics challenge the ontological cost of positing bare substrata and question whether properties alone can explain objecthood without such substrata.

In modern debates, substantialists engage with issues in metaphysics, philosophy of mind, and the nature of causation, often addressing how substances relate to properties, time, and change. The term should not be confused with substantivalism in the philosophy of space and time, though both discuss foundational concerns about what underlies appearances and continuities in reality.