St. Thomas Aquinas: Faith, Reason, and the Existence of God

Learning Outcomes

1. Understand the interrelationship between faith and reason in Aquinas’ philosophy.
2. Examine Aquinas’ arguments for the existence of God.
3. Explore how Aquinas synthesizes Aristotelian philosophy with Christian theology.
4. Analyze the role of metaphysics and epistemology in Aquinas’ thought.

The Role of Faith and Reason in St. Thomas Aquinas’ Philosophy

St. Thomas Aquinas is one of the most prominent figures in medieval philosophy and theology, with his work forming a cornerstone in the integration of faith and reason. Aquinas believed that faith and reason are not opposed but rather complementary. He argued that both have their proper domain, and when used correctly, they lead to the same ultimate truth: the existence of God.

1. Faith and reason: Aquinas posited that faith is a kind of knowledge that surpasses human reasoning, but it never contradicts reason. He claimed that truths of faith, such as the Trinity or Incarnation, are beyond the full comprehension of human reason but are still logically coherent. Faith is not irrational; it belongs to a different epistemic domain than reason.

2. Reason as an independent source of knowledge: For Aquinas, reason is capable of discovering truths about the world and even proving the existence of God. However, reason has limits, particularly when it comes to knowledge of divine mysteries. Natural theology, according to Aquinas, operates through reason, while revealed theology stems from faith.

3. The synthesis of faith and reason: Aquinas famously synthesized Aristotelian philosophy with Christian doctrine. His epistemology asserts that while reason can lead to many truths about God and the world, certain truths can only be known through divine revelation. This interplay between faith and reason is foundational in Aquinas’ approach to theology and metaphysics.

Important Note: Faith and reason operate on different planes but aim toward a unified truth. The truth of reason complements the truth of faith, and for Aquinas, these two domains lead to a harmonious understanding of reality.

Aquinas’ Proofs for the Existence of God

St. Thomas Aquinas’ most famous contribution to the debate on the existence of God is his Five Ways, which are found in his seminal work, the Summa Theologica. These arguments are deeply rooted in Aristotelian metaphysics, and they seek to show how human reason can arrive at the conclusion that God exists.

1. The Argument from Motion: Aquinas begins with the premise that everything in motion must be moved by something else. However, there cannot be an infinite regression of movers, so there must be a First Mover, which is not moved by anything else. This First Mover, according to Aquinas, is what we call God.

2. The Argument from Efficient Causes: In the world of sensible objects, we observe a series of causes and effects. But every effect must have a cause, and there cannot be an infinite chain of causes. Therefore, there must be a First Cause, which is itself uncaused. This is what Aquinas identifies as God.

3. The Argument from Possibility and Necessity: Aquinas observed that things in the world come into existence and pass out of existence; they are contingent. However, if everything were contingent, there would have been a time when nothing existed, and nothing could have come into existence. Thus, there must be a Necessary Being that always exists and brings contingent beings into existence. This Necessary Being is God.

4. The Argument from Gradation: In the world, we find degrees of goodness, truth, and nobility. These gradations imply the existence of a maximum, a being that is the highest in all qualities. Aquinas argues that this perfect being is God.

5. The Argument from Design (Teleological Argument): The final argument observes that non-intelligent things act toward an end. For instance, natural bodies act in regular and predictable ways. Aquinas argues that these entities could not act toward a purpose unless directed by a being endowed with intelligence. This guiding intelligence is God.

Process flow of First Mover argument:
Motion in the world → must be caused by another → cannot regress infinitely → therefore, there must be a First Mover → the First Mover is God.

Comparisons between the Five Proofs

The Relationship Between Epistemology and Metaphysics in Aquinas’ Thought

St. Thomas Aquinas’ approach to the existence of God is inseparable from his broader epistemological and metaphysical views. His natural theology emphasizes that human beings can know God through reason, while his revealed theology insists that certain truths about God require faith. This interplay shapes both his epistemology (how we come to know things) and his metaphysics (the nature of being and reality).

1. Epistemology and sense perception: Aquinas was a firm believer in empiricism, the idea that knowledge begins with the senses. Borrowing from Aristotle, he argued that all human knowledge starts with the perception of the external world. From there, the mind abstracts universal truths.

2. Metaphysics and being: For Aquinas, the study of being is crucial to understanding reality and God. Everything that exists is either a necessary being or a contingent being. God is the only necessary being, whose existence is not contingent on anything else, while everything else in the world is dependent on God.

3. The analogy of being: Aquinas used the concept of the analogy of being to explain how we can talk about God. Since God is infinitely different from creatures, we cannot use univocal language to describe Him. Instead, we use analogical language: when we say “God is good,” the term “good” is used analogically, not in the same sense that we say a human is good.

Important Note: Aquinas emphasizes that while human reason can approach the knowledge of God, certain truths—such as the nature of the Trinity—remain mysteries that can only be grasped through faith.

The Interplay of Aristotelian and Christian Thought

Aquinas’ system of thought represents a profound fusion of Aristotelian philosophy and Christian theology. This synthesis allowed him to develop a rational framework for understanding the existence of God, the nature of the soul, and the purpose of human life.

1. Aristotelian influence on Aquinas: Aquinas adopted Aristotle’s metaphysical concepts of form and matter, the four causes, and the idea that everything in nature has a purpose, or telos. He modified Aristotle’s view of the Unmoved Mover by identifying it with the Christian God.

2. Christian modification of Aristotle: While Aristotle believed in a distant, uninterested God, Aquinas argued that God is personal, immanent, and actively involved in the world. He retained Aristotle’s emphasis on reason but also insisted that faith is a valid and necessary way of knowing God.

3. Ethics and the natural law: Aquinas’ ethics is based on the notion of natural law, which is derived from reason and reflects the moral order inherent in nature, as ordained by God. His ethical thought merges Aristotle’s concept of virtue ethics with Christian moral principles.

Conclusion

St. Thomas Aquinas’ exploration of the relationship between faith, reason, and the existence of God remains one of the most influential systems in Western philosophy and theology. By harmonizing Aristotelian metaphysics with Christian doctrine, Aquinas laid the foundation for a comprehensive philosophical theology that continues to resonate in discussions of epistemology, metaphysics, and the role of human reason in understanding the divine.

MCQ: Which of the following is not one of Aquinas’ Five Ways of proving the existence of God?

1. Argument from Motion
2. Argument from Design
3. Argument from Moral Obligation
4. Argument from Possibility and Necessity
   Answer: 3