Ontological arguments

• Ontological arguments

  • Deductive a priori arguments.
  • Prove that God has all perfections, but do not show that he created the universe and is a personal God.
• St Anselm's ontological argument 


  P1: God is that than which nothing greater can be conceived.

  P2: Even a fool (an atheist) Can understand that God is the greatest possible being.

  P3: The fool says that there is no God in reality.

  P4: The fool is convinced that God exists only in his understanding, not in reality.

  P5: it is greater to exist in both the understanding and reality than merely in the understanding.

  P6: To genuinely be the greatest, the greatest possible being must exist in both the understanding and the reality.

  C: God exists in reality.
• Descartes' ontological argument 


  P1: I have an idea of God, a perfect being.

  P2: A perfect being must have all perfections.

  P3: Existence is a perfection.

  C: Therefore God exists.
• Norman Malcom's ontological argument


  P1: God cannot come into existence.

  P2: So if God does not exist then his existence is logically impossible.

  P3: if God exists, then his existence is logically necessary.

  P4: Either God's existence is logically impossible or logically necessary.

  P5: God's existence is not logically impossible (because the concept of God is not self-contradictory).

  P6: Therefore God's existence is logically necessary

  C: Therefore God exists.
• Gaunilo's perfect island objection


  P1: There is a lost island which is the most excellent of all islands.

  P2: No one has difficulty conceiving of this lost island, it exists in our understanding.

  P3: It is more excellent to exist in the understanding and in reality, rather than in the understanding alone.

  C: Therefore the most excellent of all islands must exist.
• Hume's empiricist objection to a priori arguments for existence


  P1: Nothing that can be distinctly conceived entails a contradiction.

  P2: For any being that we can conceive of as existent, we can also distinctly conceive of that being as non-existent.

  C: Therefore there isn't any being whose non-existence entails a contradiction.
• Ayer's empiricist objection to a priori arguments for existence


  P1: A priori propositions are certain because they are tautologies.

  P2: From a set of tautologies, only further tautologies can be validly deduced.

  P3: The existence of anything, including God, is not a tautology.

  C: Therefore we cannot validly deduce the existence of God from a priori propositions, and the ontological argument fails.
• Predicate


  The properties we are claiming the subject has e.g., red. 
• Kant's objection based on existence not being a predicate.


  P1: A genuine predicate ads to our conception of a subject and helps to determine it.

  P2: Existence does not add to our conception of a subject or help determine it.

  C: Therefore existence is not a genuine predicate.