Ontological Argument

Anselm & Descartes et al

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  • Created by: Amy
  • Created on: 29-04-12 17:09

Anselm & Gaunilo

  • "God is the most perfect being"
  • aliquid quo nihil maius cogitari possit -'that than which no greater can be thought'
  • Even the fool (someone who does not believe in God) undestands that
  • To be perfect, God must exist
  • Therefore God must exist otherwise we should be able to conceive of something greater, than that which nothing greater can be conceived – which is absurd.

  • Gaunilo: how can you say something must exist because you have given it a definition of being perfect? It is absurd; it would mean that anything must exist, e.g. a perfect island or a unicorn. "my unicorn is different to everyone else's unicorn" - same of God?
  • Anselm’s answer was that an island could conceivably not exist – it depends on external factors.  It has contingent existence, whereas God, by his very nature, has necessary existence.  It is inconceivable to think that God might not exist.
  • reductio ad absurdum” "There is no God”. By making this denial, argues Anselm, the fool has the idea of ‘God’ in his mind. However, because of the definition of God and with existence being part of that greatness, then it follows that God must exist.
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  • Arthur Schopenhauer (1788-1860), referred to the ontological argument as a ‘sleight of hand trick’ and ‘a charming joke’ and the argument strikes many people as suspicious in some way.

    Detailed Gaunilo:

    • I can conceive of the most real and perfect island
    • It is greater to exist in the mind and in reality than to exist in the mind alone
    • So this lost but perfect island must exist in reality as well as in the mind
    • The notion of a real and perfect island is absurd
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  • We have an imprinted knowledge of God (innate) “The baby in the womb has in itself the ideas of God”
  • Knowledge of God can be compated to Maths (it cannot be doubted)
  • God compared to a triangle: in their nature, or defintion, is immutable. By defintion, a triangle has 3 sides and adds up to 180 degrees. It's inconceivable to think of a triangle without these properties.
  • Same principle as Anselm: the definition is perfection and must therefore exist.
  • "It would therefore be inconceivable to think of God withotu the property of existence"
  • Only God had the defintion of perfection; therefore existence becomes a defintion of God.
  • God must exist, like a mountain must have a valley
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Kant's Response to Descartes

  • Definitions are made of predicates, that give us a description or clear picture of what we are defining.
  • Existence is not a predicate, and therefore cannot be used as part of God's definition.
  • If you have a triangle - it is true that you must have 3 sides and angles - but you don't have to have the triangle in the first place
  • The same is true of God


  • Charles Hartshorne things that existence is a predicate
  • because it gives us additional information
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Russell and Moore


If we are referring to something; it is assumed we are referring to something that exists, rather than something imaginary.

HOWEVER... we can easily refer to a unicorn; a work of fiction.


  • "Some tame tigers do not growl" - meaningful statement,  as it tells us such beings exist and a describes a characteristic of the aforementioned being
  • "Tame tigers do not exist" is a meaningless statement as we learn nothing from it, apart from the fact that they do not exist; therefore we should not even talk about them
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Lauren Clayton


I really like this, very useful and detailed, thanks!

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