St Aquinas

Summary of Summa Theologiae

  • Structure of Summa Theologiae

    • Three main parts:

      • Part One: Presence of God in creation.

      • Part Two: Presence of God by grace in the souls of the just.

      • Part Three: Presence of God in Christ and the Church.

    • Core theme: Extended meditation on the presence of God.

The Existence of God

  • Key Question: Does God exist?

  • Faith: One way to know God’s existence is through faith based on the Bible.

  • Natural Knowledge:

    • St. Paul (Romans 1:20) indicates that God's existence is known through the beauty and goodness of the natural world.

    • Ancient philosophers, who never read the Bible, also argued for God's existence.

    • Aquinas teaches that natural reason provides knowledge of God.

Development of Knowledge of God

  • Spectrum of Understanding:

    • Knowledge of God is common and confused; not always explicit or clear.

    • Development depends on individual interest, cultural circumstances, and intellectual gifts.

  • Obstacles:

    • Factors such as cultural circumstances can hinder the full development of natural knowledge of God.

  • Philosophical Arguments:

    • Some individuals may cultivate robust philosophical proofs for God's existence after extensive reflection and study.

Aquinas's Five Ways

  • Basic Principle: Knowledge of God's existence is inferred from our experiences in nature by seeking an ultimate explanation.

  • Analogies:

    • E.g., Inferring a fire from smoke; witnessing symptoms infers an underlying infection.

The Five Ways

  1. First Way:

    • Observes motion/change in nature; concludes the necessity of a first unmoved mover.

  2. Second Way:

    • Examines cause and effect; deduces the necessity of a first uncaused cause.

  3. Third Way:

    • Considers contingent beings; concludes there must be a source of existence that cannot not exist.

  4. Fourth Way:

    • Inspects degrees of perfection in beings; leads to the conclusion of a perfect being as the source.

  5. Fifth Way:

    • Observes that unintelligent beings act towards ends; deduces a higher intelligence directing them.

  • Meditation on Presence: The arguments lead to meditations on how God moves, causes, and directs all things.