Thomistic Principles: Aristotle's Influence on Existence

Thomistic Principles: Aristotle's Influence

St. Thomas Aquinas retains many Aristotelian principles to explain the material world, incorporating elements from Plato's system. Thomistic metaphysics is therefore both Platonic and Aristotelian.

Preceding thinkers, including St. Thomas, sought to understand what distinguishes the world and what explains its existence. Through an analysis of the concept of creation, St. Thomas concluded that the difference between God and other beings is that they are created. In contrast, God necessarily exists and cannot not exist; He is necessary being.

Essence and Existence

This led Aquinas to distinguish between essence and existence, defining essence as what things are—their inherent nature—and existence as the fact of their being or not being.

For Aquinas, the "criterion of composition" is appropriate: creatures are composed of matter and form, while God is unique. Beings are composed of existence and essence, but in God, these are one and the same.

Contingency and Creation

The consequences of this distinction show the contingency and creation of the world by God. The existence of God is necessary, while created beings only have derived existence. Angels and other spiritual substances are composed of essence and existence. Ultimately, the self is defined as an essence, necessarily indicating being, which is God.

Platonic Theory of Participation

Aquinas explains how the existence of God relates to created beings through the Platonic theory of participation. He defines this concept as follows: "To be created is part of the agent or efficient cause." Because God created beings to exist, the existence of God must be involved. God allows these beings to share in His life.

This definition of participation includes elements of Plato, Aristotle, and Christianity.

Causality and Contingent Beings

Causality, a Platonic concept, serves Aquinas to explain the basis of God in creating contingent beings. It is based on the assertion that God is the supreme model. In Him are all possible perfections. Creatures are composed of essence and existence. Depending on how well each being imitates God, it will participate to a greater or lesser extent in His perfections.

Hierarchy of Being

Aquinas establishes a hierarchy in which God represents the maximum degree of perfection, followed by angels and other spiritual substances. Man, among material beings, is most like God, followed by nonrational animals, plants, and nonliving things.