Notes on Thomas Aquinas' Summa Theologiae and Five Ways for God's Existence

Overview of Summa Theologiae

• Three Main Parts:
  1. Presence of God in Creation
  2. Presence of God by Grace in Souls of the Just
  3. Presence of God in Christ and His Mystical Body (the Church)
• Central Theme: Extended meditation on the presence of God.

The Question of God's Existence

• Key Question: Does God exist?
• Thomas Aquinas' Approach: Addresses the existence of God with his famous five proofs.
• Human Knowledge of God:
  • Can be known through faith based on the Bible.
  • In Romans 1:20, it is suggested that God's existence is known universally through the natural world.

Natural Knowledge of God

• Biblical Confirmation:
  • Romans 1:20 and Wisdom 13:1-9 indicate awareness of God without knowledge of scripture.
• Aquinas' Findings:
  • Ancient pagan philosophers argued for God's existence without the Bible.
  • Natural Knowledge of God:
    • Accessible through human reason and intelligence.
    • Not always explicit or clear, but exists on a spectrum of cognitive development.
    • Influenced by cultural circumstances.

Development of Knowledge

• Spectrum of Knowledge:
  • Common and confused knowledge exists for everyone.
  • Some may develop robust philosophical proofs over time.
• Challenges:
  • Development hindered by sin, denial, and false philosophies.
  • Agnosticism and atheism are possible but do not negate the possibility of natural theology.

Fundamental Principle of the Five Ways

• Inference from Experience:
  • Knowledge of God is inferred from the visible effects in the natural world.
  • Example of reasoning: smoke indicates fire, similar to nature signaling God's existence.
• Development of Ideas:
  • Knowledge of God can grow through study and philosophical inquiry.

The Five Ways of Thomas Aquinas

1. First Way (Motion):
   • Observes change and motion; concludes there must be a first mover/unmoved mover.
2. Second Way (Cause and Effect):
   • Examines causality; deduces a first cause/un-caused cause must exist.
3. Third Way (Contingent Beings):
   • Considers contingent beings (those that exist but don't have to); infers a necessary being must exist.
4. Fourth Way (Grades of Perfection):
   • Noticed varying degrees of perfection; concludes there must be a perfect being that is the source of perfection.
5. Fifth Way (Intelligent Design):
   • Observes non-intelligent beings acting towards an end; infers a supreme intelligence must direct them.

Conclusion

• Significance: Each way offers a framework for meditating on the presence of God in the world.
• God's Role: Present in movement, causation, being, and direction of existence.