The Relationship Between Faith and Reason in the Philosophy of St. Thomas Aquinas
The Harmony of Faith and Reason in St. Thomas Aquinas
The Faith-Reason Debate in Medieval Philosophy
The Middle Ages witnessed a persistent conflict between faith and reason. Philosophers responded to this conflict in diverse ways, often prioritizing one over the other. St. Thomas Aquinas sought to unify these two forces, particularly in his demonstrations of God’s existence, where he employed reason to justify the foundations of religion.
Thomistic Metaphysics: An Aristotelian Foundation
St. Thomas’s metaphysics is deeply influenced by Aristotle. Like Aristotle, he envisioned a unified reality, rejecting Platonic dualism. To explain change in the world, both philosophers utilized two key conceptual pairs:
- Actuality and Potentiality: These define the present state of a substance and its potential for future change, respectively. Movement is understood as the transition from potentiality to actuality (“nothing moves unless, as a power, it is directed to that by moving”).
- Matter and Form: Substance is seen as an inseparable compound of matter and form. Form represents the essence of a thing, eternal and unchanging, while matter is its embodiment.
These concepts form the basis of hylomorphism, a theory that St. Thomas applied to anthropology.
The Hylomorphic View of Humanity
For St. Thomas, a human being is a substance composed of body and soul in a natural union. These constitute the essence of humanity, interacting in such a way that the soul determines the characteristics of the person, while the body provides the soul with knowledge through the senses. This unified concept, however, does not preclude St. Thomas from affirming the immortality of the soul.
Although forming a compositum, the soul is a subsistent form capable of existing without the body and is incorruptible.
Thomistic Epistemology: Knowledge as a Unified Act
St. Thomas’s epistemology derives from his hylomorphic anthropology. He identifies knowledge as an act of the compound resulting from the substantial union of body and soul. He distinguishes between two types of knowledge:
- Universal Knowledge: This involves the abstraction of common elements and universal concepts from sensory experience (abstraction and individuation).
- Sensitive Knowledge: This is the knowledge perceived through the senses.
Sensitive knowledge forms the starting point for his proof of God’s existence (“For it is true, and what is perceived by the senses, that in this world we move”).
The Demonstration of God’s Existence
For St. Thomas, the existence of God is not self-evident. If it were, a demonstration would be unnecessary. Conversely, if it is not self-evident to us, then proof is required. His originality lies in treating the cause of his work as purely intellectual, demonstrating the possibility of constructing a rational theology. While accepting the religious attributes of God (the Unmoved Mover, Pure Act), St. Thomas grounds his demonstration of God’s existence on a sensory fact (“For it is true, and what the senses perceive, that in this world we move”) and applies an Aristotelian principle (“everything that moves is moved by another […] who moves this in action”).