Aquinas's Metaphysics: Essence, Existence, and the Five Proofs of God

The Metaphysics of St. Thomas Aquinas

St. Thomas Aquinas is the chief representative of Scholasticism. He sought to bring man's religious life into the field of intelligence. For this purpose, he models himself after Aristotle, incorporating what is rational beyond divine revelation. His primary aim is to unite faith and reason, merging Aristotelian philosophy with Christian revelation.

Aquinas distinguishes between the object of philosophy (created being) and the object of theology (the Creator). He develops this distinction in his Metaphysics.

Aristotelian Categories and the Concept of Existence

Aquinas accepted Aristotle's theory regarding the different modes of being and the following categories:

1. Substance: That which exists in itself.
2. Accidents: Qualities that exist in a substance.

He also adopted the difference between being in act and being in power (Aristotle's framework for explaining motion). Furthermore, Aquinas accepted the idea of Hylomorphism, according to which every created substance is composed of matter and form.

Crucially, Aquinas added a new category: Existence.

Essence, Existence, and the Division of Beings

Aquinas distinguishes between essence (what a thing is, its substance) and existence (that it is). For a created substance, existence is dependent on the creative will of God. God is the Creator of all beings, making creation possible.

Thus, Aquinas divides beings into two groups:

1. Created Beings (Contingents): These beings exist because God has exercised His voluntary creative action. This group includes man.
2. The Creator Being (God): God is Pure Act, meaning He is pure existence itself.

Metaphysics is concerned with created being, while rational theology is concerned with the other being—the creative being.

Key Theological Concerns

Aquinas addresses two primary theological concerns regarding God:

1. The Existence of God.
2. The Substance (Nature) of God.

1. The Existence of God

Aquinas held that the existence of God is a truth that can be reached by reason, though he found it necessary to justify this truth through revelation.

The Five Ways (Proofs of God's Existence)

The Five Ways (Quinque Viae) are proofs or arguments based on empirical observations of the world:

• 1st Way: Argument of the Unmoved Mover: Based on the existence of movement in the world.
• 2nd Way: Argument of the First Cause: Based on the fact that all beings in the world are caused.
• 3rd Way: Argument from Necessity and Contingency: Based on the fact that all things and events are possible (contingent).
• 4th Way: Argument from Degrees of Perfection: Based on the existence of beings with varying degrees of perfection.
• 5th Way: Argument from Governance (Intelligent Design): Based on the observation that all non-rational beings pursue specific ends or purposes.

2. The Substance of God

Aquinas describes the nature (substance) of God using three methods (or ways of knowing):

1. The Way of Negation (Via Negativa): The classical negative way, stating what God is not (e.g., God is not finite, not temporal).
2. The Way of Eminence (Via Eminentiae): Attributing positive qualities to God in a supreme or eminent degree (e.g., God is supremely good, supremely wise).
3. The Way of Affirmation (Via Affirmativa): Stating what God truly is, since He corresponds to the maximum extent of being (e.g., God is Being itself).