The Ontological Argument for God's Existence and Aquinas's Proofs

Existence of God

The Ontological Argument of St. Anselm

St. Anselm (11th Century) formulated the ontological argument. He argued that the concept of God implies the real existence of God. Anselm posited that God is that than which nothing greater can be conceived. If such a being existed only in the mind, a greater being could be conceived—one existing both in the mind and in reality. Therefore, God must exist in reality.

Criticism by Aquinas

St. Thomas Aquinas argued against this formulation. He asserted that real existence cannot be deduced solely from essence. To know that something exists, we must start from what exists, which we know through the senses. The concept of God is unique because it is considered the *most perfect*; however, Aquinas believed that existence cannot be proven merely from this conception.

Aquinas's A Posteriori Arguments

For St. Thomas, proving God's existence requires a posteriori arguments, which proceed from effect to cause. These arguments demonstrate God's existence starting from sensible realities (effects) up to a root cause, which is God. Aquinas presented five ways to demonstrate God's existence:

The Five Ways to Prove God's Existence

1. First Way: The Unmoved Mover

   Everything that moves is moved by another. This series cannot be infinite; therefore, there must be a First Mover that is itself unmoved. This is GOD.

2. Second Way: The Efficient Cause

   Everything that is caused is the effect of a preceding cause. This series of causes cannot extend indefinitely; thus, there must be a First Cause, which all call God.

3. Third Way: Contingent Beings

   Things come into existence and cease to exist; they are contingent. There must have been a time when nothing existed. Therefore, there must be a being that is necessary, upon which all contingent beings depend. GOD is this necessary being.

4. Fourth Way: Degrees of Perfection

   Some things are more or less good, true, or perfect than others. In the series of beings possessing limited perfection, this cannot be carried to infinity. Therefore, there must exist a supreme being possessing perfection in the highest degree—the first and ultimate cause of all perfection.

5. Fifth Way: The Order of the World (Teleological Argument)

   Natural things, which lack intelligence, act toward an end. Those that lack knowledge are directed toward an end by some other being. Therefore, there exists an intelligent being who directs all natural things to their end. GOD.

Outline of Aquinas's Proofs

• Starting Point: A fact of experience.
• Proof Progression: Applying the principle of causality to the fact of experience, demonstrating the impossibility of an infinite regress in the series of subordinated causes.
• Conclusion: The uncaused first cause is God.

Natural Law and Freedom

Natural beings are governed by physical laws, not by choice. Man, however, is free, and therefore his behavior is ordered by the moral law, which respects freedom. The eternal law is participated in by rational creatures as the natural law.