Notes from the A2 conference – The ontological argument

This argument is based on a definition of God.

If we can agree on a definition we should be able to agree on a conclusion.


No based on evidence and therefore more rational.

If the premises are sound we must accept the conclusion

De dicto – by definition

In intellectu – in the mind

Critics say existence doesn’t add anything to our understanding of God however Anselm says yes it does – to know of his existence is not the same as knowing him and one cannot know him if he does not exist.

Gaunilo‘s island – if the island is perfect it must exist because existence is a ‘perfection’ BUT it doesn’t!

Anselm said contingent things can always be added to there fore can never be perfect; only a non-contingent being cannot be added to therefore the onto argument only applies to necessary beings.

Gasking: the creation of the universe is the greatest achievement

  • The greater the achievement the more impressive if the creator is limited
  • The greatest limit would be non=existence
  • Therefore the creation of the universe by a non-existing creator is greater than by an existing one
  • Therefore God does not exist!!
  • Reduction ad absurdam!!


  • God can either exist or not
  • If he doesn’t then not most perfect conceivable being
  • If he does exist he cannot exist contingently
  • Therefore he must exist necessarily.

Plantinga‘s multiverse theory depends on ‘if…’

Hume – anything we can conceive of as existing we can also conceive of as not existing

He didn’t believe there was anything which was not contingent therefore God does not exist.