Aquinas's Ontology of the Material World

This monograph presents a systematic reconstruction of Thomas Aquinas's ontology of material substances, offering a contemporary philosophical interpretation that challenges prevailing readings of medieval metaphysics. Jeffrey Brower examines how Aquinas develops a sophisticated account of material objects that navigates between Platonic realism and nominalism, ultimately grounding his natural theology in a robust metaphysical framework.

The work demonstrates that Aquinas's hylomorphism—his theory that material substances are composites of matter and form—provides resources for addressing perennial philosophical problems about the nature of physical reality. Brower argues that Aquinas develops a distinctive solution to questions about material constitution, the persistence of objects through change, and the relationship between parts and wholes. This reconstruction reveals how medieval ontology offers alternatives to contemporary materialist assumptions about the physical world.

Central to Brower's interpretation is Aquinas's doctrine of prime matter and substantial form. He shows how Aquinas employs these concepts to explain both the unity of composite substances and their capacity for substantial change. The analysis clarifies how material substances can maintain their identity while undergoing accidental changes, and how new substances can come into being through generation and corruption. This framework proves essential for understanding Aquinas's broader theological commitments, particularly regarding the rational soul's relationship to the human body.

The monograph engages critically with recent interpretations of Thomistic metaphysics, particularly debates about whether Aquinas holds a constitutivist or non-constitutivist view of material objects. Brower defends a nuanced reading that acknowledges the complexity of Aquinas's position while demonstrating its philosophical coherence. He shows how Aquinas's ontology supports his arguments for divine conservation and concurrence, establishing crucial connections between metaphysics and natural theology.

The work's significance extends beyond historical scholarship to contemporary philosophy of religion. By clarifying Aquinas's ontology of material substances, Brower illuminates how medieval thinkers conceived the relationship between God and creation. The analysis reveals that Aquinas's arguments for divine existence presuppose specific metaphysical commitments about the nature of material reality—commitments that differ markedly from those underlying modern scientific materialism. This reconstruction thus contributes to ongoing debates about the compatibility of classical theism with contemporary physics and philosophy of mind.