The Ontological Argument

• Intro - ontological Argument

  • Found in proslogium, prayer book addressed to God
  • Never intended to create the ontological argument
• Psalm 14:1

  The fool says in his heart, "There is no God."
• Proslogium 2

  1. God is "than which nothing greater can be conceived"- necessary truth
  2. Psalm 14:1. There's a difference between having a concept in the mind and knowing it exists.
  3. If God's only in the mind, a greater being could be conceived, one that exists in reality.
  4. So God cannot only exist in the mind
• Why is Anselm biased?

  These are his private prayers-not meant to be critiqued and debated
• "God exists" statement

  • once God has been defined correctly, there's no doubt he exists
  • subject and predicate
  • a priori/deductive
• Gaunilo's "on behalf of the fool"

  • called ontological argument reductio ad absurdum
  • 'Perfect Island' argument
• Perfect Island


  • Everyone will imagine a perfect island to be different
  • Everyone's definition of God is different
  • Anselm didn't prove anything as he didn't prove God's existence in the first place
• Proslogium 2 and 3 responsio

  1. The island would have to be "than which nothing greater can be conceived"
  2. The greatest conceivable being cannot be conceived not to exist
  3. Conclusion: God and God alone is a necessary truth
• Necessary truth


  a proposition that is true and could not have been false, something that could not have possibly failed to exist
• Contingent truth


  A proposition that happens to be true but might have been false
• Descartes

  • created own version of ontological argument
  • defined God as "the supremely perfect being", must possess all perfect predicates
• Kant

  criticised Descartes: 2 criticisms
• Kant's criticisms

  • Existence is not a predicate
  • Something cannot be defined into existence
• Existence is not a predicate

  • adds nothing to subject
  • predicate must add extra knowledge
  • Thaler example
  • No difference between concept of God and concept that God exists
• Thaler example

  • Imagine 100 Thaler
  • Each has king's head, is round and made of metal
  • Therefore, Thaler's exist because we can describe them
  • not true
• Something cannot be defined into existence

  1. Anselm's argument is true by definition
  2. Bachelor can be defined=it exists Unicorn can be defined= it exists
  3. Unicorns may be found to be true- can only be proven by sense experience
  4. People can only know God by experiencing God
  5. Just because we can define God and Unicorns, doesn't mean either is true
• Ontological argument's failure

  • Emits the word "if"
  • IF unicorns exist, they'll be horses with horns
  • IF God exists, God will exist necessarily
• The value of Anselm's argument for religious faith

  • Doesn't require observation (strength)
  • Either fails or succeeds by logic (strength)
  • Existence is not a predicate (weakness)
• Is the Ontological argument enough to say that God exists?

  • Kant's objection shows it isnt a proof
  • Karl Barth: "it is a faith based acceptance that God exists"
• Proslogium 4 and Faith

  "A thing may be conceived in 2 ways: when the word signifying it is conceived and when the thing itself is understood"
• Anselm's example

  • "fire is water" every word can be understood but anyone who understands both fire and water knows it isnt true
  • "There is no God" every word can be understood, but a religious person understands it can't be true because they know and understand God
• Karl Barth

  argues Anselm's argument is about understanding faith
• Against Barth

  • At the start of his proslogium, Anselm says he's looking for proof
  • not religious experience
  • demonstrates the truth of his argument
  • not an argument of faith but logic
  • argument has value even if a person has faith
  • fideists disagree with any argument containing logic
  • Anselm seeks logical proof
• “it is easier to feel convinced that [the Ontological Argument] must be fallacious than it is to find out precisely where the fallacy lies.” – Bertrand Russell
• The ontological argument is a priori, meaning it cannot be disproven by new scientific understanding or evidence
• “Perhaps not everyone who hears this word “God” understands it to signify something than which nothing greater can be thought” – Aquinas.