Lecture 10: Ontological Arguments

Introduction

• Ontological arguments: Considered among the hardest arguments to deal with.
• Originally Anselm's arguments, later termed 'ontological' by Immanuel Kant.
• Argument Structure: From the concept of God to asserting God's existence.

Key Concepts

• God's Existence: Argument posits that if God possibly exists, then God necessarily exists.
• Ontological Argument Framework: Starts with the idea of a perfect God leading to arguments for actual existence.
• Common Agreement: If God exists, He is a perfect being.
• Disagreement: Over the actual existence of God, not the definition.

Historical Context

• St. Anselm: Early proponent; argument centers around the 'greatest conceivable being'.
• Other Philosophers: Descartes, Norman Malcolm, Charles Hartshorne, Alvin Plantinga, Peter van Inwagen.

Anselm's Argument

• Premise 1: Man can conceive of a greatest conceivable being (GCB).
• Premise 2: More perfect to exist than not exist.
• Premise 3: More perfect to exist outside the mind than just in the mind.
• Conclusion: To conceive such a being entails its existence; saying God does not exist is contradictory.
• Criticism: Many philosophers find it unconvincing despite difficulty identifying specific flaws.

Descartes’ Ontological Argument

• Premise 1: God has all perfections.
• Premise 2: Existence is a perfection.
• Conclusion: God must exist.
• Criticism: Kant argues existence isn't a perfection, just a fact.

Introduction of Modal Concepts

• Modal Categories: Introduced in the early 1900s.
  • Necessity: Exists in all possible worlds.
  • Possibility/Contingency: Exists in some worlds but not all.
  • Impossibility: Exists in no possible worlds.

Modern Ontological Arguments

• Norman Malcolm & Charles Hartshorne: God is either impossible or necessary. As the concept of God is not contradictory, God must be necessary.
• Alvin Plantinga: Starts with the possibility of a maximally great God leading logically to necessity and existence in the actual world.
• Peter van Inwagen: If God exists, He is necessary. It's possible He exists, thus He exists necessarily.

Conclusion

• Ontological arguments use modal logic to argue from possibility to necessity.
• Philosophically significant but not recommended for evangelism purposes.
• Next lectures will cover other arguments for the existence of God.