St. Thomas Aquinas: Metaphysics, Existence, and the Five Ways

St. Thomas Aquinas: Being and Existence

St. Thomas Aquinas posits that Being allows us to establish the contingency of the world and define the essence of God. For God, existence and essence are identical; His essence is to exist. This distinction clarifies the difference between God and the world, as the world possesses existence while God is existence. Furthermore, this framework explains the imperfection of angels, who are composed of both essence and existence, and establishes the primacy of existence.

The Existence of God: A Priori and A Posteriori

St. Anselm argued that even the most atheistic individual possesses a concept of God as the greatest conceivable being. He suggested that if one can conceive of a being greater than which nothing can be thought, then that being must exist, or else a contradiction arises. Aquinas further introduces the Five Ways (Quinque viae) to demonstrate God's existence:

• The First Way (Motion): Everything in motion must be moved by another. To avoid an infinite regress, there must be a First Unmoved Mover.
• The Second Way (Efficient Cause): Nothing can be the cause of itself. Every effect has a cause, necessitating an Uncaused First Cause.
• The Third Way (Contingency): Contingent beings rely on others for their existence. To avoid an infinite series of contingent causes, there must be a Necessary Being that is eternal.
• The Fourth Way (Gradation): We observe degrees of perfection in the world. These limited perfections imply the existence of an Unlimited or Eternal Being as the source of all perfection.
• The Fifth Way (Teleology): Intelligent beings act toward ends or purposes. Since non-intelligent beings also act toward ends, they must be directed by an Intelligent Designer, which we call God.

Moral Philosophy and Human Purpose

Regarding Moral Philosophy, Aquinas argues that humanity naturally seeks an end: happiness. Everything created has a specific purpose or function. Consequently, actions that align with our nature and fulfill our purpose are considered good, while actions contrary to our nature are considered bad.