The Influence of Aristotle on the Philosophy of St. Thomas Aquinas
St. Thomas Aquinas integrated Aristotelian philosophy into Christian theology. While Plato’s influence is present, particularly in the doctrine of participation, Aristotle’s impact is paramount. Aquinas adopted Aristotelian concepts after the Church lifted its prohibition on his teachings, making Thomistic Aristotelianism the official philosophy.
Key Aristotelian Influences on Aquinas:
- Physics: Definition of motion, hylemorphism, potency and act, and causality.
- Metaphysics: Demonstrations of God’s existence, particularly the unmoved mover.
Aquinas followed Aristotle where compatible with Church doctrine. When irreconcilable differences arose, Aquinas prioritized Church teachings.
Epistemology:
Both Aquinas and Aristotle advocated moderate empiricism combined with reason and understanding. Aquinas, like Aristotle, believed all knowledge begins with the senses. Forms or ideas are not separate from individuals, thus knowledge of God begins with concrete individuals.
Metaphysics:
Aquinas adopted Aristotelian terminology (matter, form, potency, act, substance) and defended Aristotelian realism against Plato’s idealism, evident in the problem of universals. For Aquinas, the universal exists within the thing, identifiable with the Aristotelian form.
Ethics:
Both philosophers proposed theological ethics, with ultimate happiness residing in contemplation. Aquinas’s version incorporates transcendence, where happiness is contemplation of God and natural law is grounded in God’s law. Thomistic ethics can be described as Christianized Aristotelian ethics.
The Aristotelianism of Aquinas: Structure, Nature, and God
Theory of Motion:
Aquinas adopted Aristotle’s definition of motion in terms of potency and act, classifying motion into substantial and accidental changes.
Hylemorphic Conception of Natural Substances:
Natural substances are composites of matter and form. Immaterial substances are forms without matter.
Substance and Accident:
Natural substances are subject to accidental forms.
The Four Causes:
Material, formal, efficient, and final causes, leading to a purposive interpretation of nature.
Teleology:
Aquinas accepted Aristotle’s proof of God’s existence based on motion (Thomistic First Way), proving God’s existence from sensible experience, mutability, and contingency.
Conception of God:
Aquinas adopted Aristotle’s definition of God as pure act, immutable, and perfect. God is pure thought whose object is itself. Aquinas corrected Aristotle’s view of an eternal world, asserting God’s creation of the world. God knows the world by knowing himself. Aquinas maintained the Aristotelian doctrine that God’s activity is self-knowledge.
Anthropology:
Aquinas accepted Aristotle’s definition of the soul as the life and act of a body, leading to a hylemorphic conception of human beings. Humans are single substances composed of soul and body. Departing from Aristotle, Aquinas affirmed the immortality of the soul, aligning with Plato.