Augustine & Aquinas: Faith, Reason, and the Existence of God

Augustine of Hippo (354-430 AD)

Augustine of Hippo, born in Tagaste in 354 AD, explored the relationship between faith and reason.

Faith and Reason: Credo ut intelligam (Believe in Order to Understand)

Augustine sought absolute truth, navigating through Manichaeism and the skepticism of the Platonic Academy before embracing Christianity. Influenced by Neoplatonism, he developed a theory asserting that divine illumination, stemming from innate ideas implanted by God, guides the soul. To maintain this inner light, faith and obedience to God are essential.

Faith, according to Augustine, is not irrational but rather a supernatural and divine source of knowledge obtained through illumination. Through faith, we gain understanding that would otherwise be incomprehensible. This embodies the principle of crede ut intelligas: believe in order to understand. For Augustine, knowledge implies belief, but belief does not necessarily imply knowledge.

The Existence of God

Augustine presents three arguments for the existence of God:

1. Consensus Universal: All civilizations throughout history have possessed some concept of a divine being.
2. Universal Order: The universe exhibits order, implying a creator who established this order.
3. Based on Enlightenment: There exist universal and necessary truths, such as principles of right, that transcend the temporal and changeable nature of the external world. These eternal and immutable truths must originate from an eternal and unchangeable source: God, the Truth residing within our souls. The truth of the sensible world participates in God's Truth, manifested in His ideas, which serve as exemplary models for the world.

Platonic Influence

Augustine adapted Platonic ideas to Christian dogma:

1. The division between the immortal soul and the mortal body. However, Augustine diverges from Plato by asserting that the soul is created by God, not eternally pre-existing.
2. Innate ideas, which Plato believed the soul possessed before entering the body, are, according to Augustine, gifts from God.
3. Plato's concepts of opinion and intelligence correspond to Augustine's notions of reason and faith.
4. The concept of illumination in Plato resonates with Augustine's emphasis on divine enlightenment.
5. The presence of God in the soul mirrors Plato's idea of inherent goodness.
6. Augustine's ideas are copies of Plato's forms in the intelligible world.
7. The intelligible world of Plato's ideas is analogous to the City of God, presided over by God and the saints, as described by Augustine.

Thomas Aquinas (1225-1274 AD)

Reason and Faith

While Augustine posits that knowledge requires inner illumination from innate ideas bestowed by God, linking reason and faith, Aquinas argues for the compatibility of reason and faith. Aquinas states that reason can aid in demonstrating the truths of faith, accepting divine revelation, illustrating revealed truths to defend against skeptics, and demonstrating that mysteries are intelligible, not absurd.

Faith, in turn, can guide reason by revealing truths inaccessible to reason alone, confirming truths discovered through reason, and serving as a criterion when conclusions conflict with religious doctrine. Aquinas aimed to establish theology as a science.

The Existence of God: The Five Ways

(Explanation of Aquinas's arguments): Thomas argues that understanding God requires grounding in reality, employing a posteriori proofs known as the Five Ways:

1. The Argument from Motion: The existence of motion and change implies a Prime Mover, itself unmoved and unchanging: God.
2. The Argument from Causation: The existence of caused events implies an uncaused cause: God.
3. The Argument from Contingency: The existence of contingent beings implies a necessary being: God.
4. The Argument from Degree: The varying degrees of perfection in beings imply a perfect being: God.
5. The Argument from Design: The order and purpose in the universe imply an intelligent designer: God.

Therefore, God is immutable, pure act, uncaused cause, ideal, necessary, and the entity that orders the world.

Rational-Philosophical Attitude

Aquinas adopted a rational-philosophical attitude of confidence in reason, emphasizing its importance while distancing himself from modern rationalism. His worldview is based on methodical thinking, clarity, and stability of ideas. He affirms:

1. The existence of innate ideas.
2. A direct relationship between thought and reality.
3. Deductive reasoning as a means of knowledge acquisition.
4. The fundamental nature of substance.