Saint Anselm's Ontological Argument for God's Existence

Saint Anselm's Philosophical Works

The Monologion: Reflections on Divine Essence

In the Monologion, Anselm presents a series of reflections on the divine essence that lead to a demonstration of the existence of God. He posits that God is the source of all goodness, truth, and beauty, and that all that exists does so through participation in a single, supreme Being: God.

The Proslogion: Anselm's Ontological Argument

The Proslogion introduces Anselm's groundbreaking first proof of principle, famously known as the ontological argument. While later philosophers like Thomas Aquinas and Immanuel Kant criticized it, the argument found wide acceptance in modern philosophy by rationalist thinkers such as René Descartes.

Understanding the Ontological Argument

Saint Anselm's enduring fame largely stems from his demonstration of God's existence, which exemplifies the harmony between faith and reason. This proof, termed the 'ontological argument' by Kant, is an a priori argument that takes the form of a reductio ad absurdum. The Proslogion argument is based on the following key assumptions:

Key Assumptions of the Proslogion Argument

• The idea of God, as provided by revelation (e.g., through the Holy Scriptures).
• The identity of the logical order with real existence, implying that what exists in thought also exists in reality (often summarized as esse est intelligi – to be is to be understood/thought).
• The consideration of God's existence as an attribute or perfection of His essence.

Structure of the Ontological Argument

1. The Problem: Conceiving God

   The argument begins with the simple concept of God to prove His existence. Even someone who denies God's existence must possess some idea or concept of God, for one cannot deny something of which they have no idea.

2. Starting Point: The Greatest Conceivable Being

   The 'fool' (as Anselm refers to the atheist) understands the idea of "something than which nothing greater can be conceived."

3. First Step: Existence in the Understanding

   The fool must accept that this "something than which nothing greater can be conceived" exists at least in the understanding.

4. Second Step: Existence in Reality

   However, that than which nothing greater can be conceived cannot exist only in the understanding; it must also exist in reality. If it existed only in the understanding, then a greater being—one that exists both in the understanding and in reality—could be conceived. This would contradict the initial premise that it is "that than which nothing greater can be conceived." Therefore, it must exist in reality as well.

5. Conclusion: God's Necessary Existence

   Therefore, there exists, both in the understanding and in reality, something than which nothing greater can be conceived—and this, Anselm concludes, is God.