Ontological arguments

• Ontological Argument

  Arguments for the existence of God based on the nature of reality or being.

  A Priori deductive arguments
• Anselm's Chapter 2 argument:

  P1- It is a conceptual truth (or, so to speak, true by definition) that God is a being than which none greater can be imagined (that is, the greatest possible being that can be imagined).​​

  P2] God exists as an idea in the mind.​​

  P3] A being that exists as an idea in the mind and in reality is, other things being equal, greater than a being that exists only as an idea in the mind.​​

  04] Thus, if God exists only as an idea in the mind, then we can imagine something that is greater than God (that is, a greatest possible being that does exist).​​

  P5] But we cannot imagine something that is greater than God (for it is a contradiction to suppose that we can imagine a being greater than the greatest possible being that can be imagined.)​​

  C] Therefore, God exists.​​
• Anselm's Chapter 3 Argument

  P1] By definition, God is a being than which none greater can be imagined.​​

  P2] A being that necessarily exists in reality is greater than a being that does not necessarily exist.​​

  P3] Thus, by definition, if God exists as an idea in the mind but does not necessarily exist in reality, then we can imagine something that is greater than God.​​

  P4] But we cannot imagine something that is greater than God.​​

  P5] Thus, if God exists in the mind as an idea, then God necessarily exists in reality.​​

  P6] God exists in the mind as an idea.​​

  P7] Therefore, God necessarily exists in reality.
• 3 Marks: Outline Anselm's Ontological Argument for God​

  Anselm's ontological argument for the existence of God suggests that:​

  God is a being than which none greater can be conceived. ​

  I can conceive of such a being, so that being is non-contradictory. ​

  If I could imagine a greater being, then that being would be God instead. ​

  It is greater to exist in the mind and in reality, than to only exist in the mind. ​

  Therefore, God exists in the mind and in reality.​
• Gaunilo's Objection [1]

  God is a necessary being is true if God exists and false if God does not exist, but we are no closer to knowing if God must exist or not.​
• Gaunilo's perfect Island objection [2]

  -Imagine an island than which none greater can be conceived.​

  -This perfect island would be greater if it existed in the mind and in reality, than just in the mind.​

  -However, this would lead to the absurd conclusion that billions of perfect islands exist, which they obviously don't!​

  -Just because the perfect island is greater if it exists in the mind and in reality, than just in the mind does not mean it must exist.​

  -Therefore, Anselm's argument is false.​
• Anselm's response to Gaunilo

  -The island is contingent, it depends on the sea and the earth, they are not necessary

  -Nothing exists independently from something else

  -But God is supremely necessary

  -He is not dependent, so the argument is only for God

  -The idea of a perfect Island is subjective, but God's perfection is objective

  
  

  Essentially: Being the greatest conceivable being is an essential property of God and only God.​​
• Descartes's ontological argument for God's existence

  P1] I have an idea of God, so it is coherent.​

  P2] My idea of God is a 'supremely perfect' being.​

  P3] A supremely perfect being does not lack any perfection.​

  P4] Existence is a perfection.​​

  C] Therefore, God must exist.
• Descartes vs Anselm arguments

  -Descartes uses 'supreme perfection' to define God, whereas Anselm defines him as 'that than which nothing greater can be imagined'.​

  
  

  -Descartes claims that 'existence is a perfection' Anselm merely claims 'it is greater to exist in the mind and in reality, than just in the mind'.​
• Hume's objection to ontology

  Hume objects to ontological arguments because they treat existence as analytic a priori things and therefore relations of ideas, but he argues that to know whether something exists must be experienced to be known to be true or false. The reason for this is it is possible to imagine anything as either existing or not existing. This makes them matters of fact, and therefore cannot be made true a priori or understood by definition, even about God.
• Kant's Objection to Ontology

  P1] If 'God does not exist' is a contradiction, then 'God exists' is an analytic truth.​

  P2] If 'God exists' is an analytic truth, then 'existence' is part of the concept 'God'.​

  P3] Existence is not a predicate; something that can be added on to another concept.​

  C1] Therefore, 'existence' is not part of the concept God.​

  C2] Therefore, 'God exists' is not an analytic truth.​

  C3] Therefore, 'God does not exist' is not a contradiction.​

  C4] Therefore, we cannot deduce the existence of God from the concept of God.​

  C5] Therefore, ontological arguments cannot prove that God exists.

  
  

  Thalers example, no difference between real Thalers and the concept of 100 qualities. the predicate of existence doesn't add anything.
• Subject [kant]


  The thing you're talking about
• Predicate [Kant]


  Something about the subject​.

  So, a predicate is a kind of property that is either true or false about a subject. Things that can be neither true nor false is not a predicate, for example.​
• Malcom on Anselm's second arguments:

  -'God is the greatest possible being' is logically part of our concept of God.​​

  -A being that depends on something for its existence is not as great as one that doesn't. ​

  -The reason for this is that by depending on something else you are suggesting that the other being has a power that you do not.​ For God to have the greatest power, he would have greater power than anything else so it capable of being fully self-sufficient.​

  -Therefore, God's existence cannot depend on anything.​ If God exists, then God's existence is necessary.​
• Malcom on Kant's objection:

  Existence is not a predicate, but necessary existence is a predicate because it is only true of God, nothing else. This would imply that 'It necessarily exists' does add on the subject 'God', making it a predicate.​
• Malcom's ontological argument:


  P1] Either God exists or God does not exist.​​

  P2] God cannot come into existence or go out of existence.​​

  P3] If God exists, God cannot cease to exist. ​​

  C1] Therefore, if God exists, God's existence is necessary.​​

  P4] If God does not exist, God cannot come into existence. ​​

  C2] Therefore, if God does not exist, God's existence is impossible.​​

  C3] Therefore, God's existence is either necessary or impossible.​​

  P5] God's existence is only impossible if the concept of God is self-contradictory.​​​

  P6] The concept of God is not self-contradictory.​​​

  C4] Therefore, God's existence is not impossible. ​​​

  C5] Therefore, God exists necessarily. ​​
• Gaunilo on Malcom:


  Malcolm can still be challenged by the Gaunilo argument that conceiving of a necessary being doesn't make the necessary being true, it just makes it true only if the being exists.
• Malcom making a fallacy:

  -Malcolm poses a false dichotomy fallacy by suggesting that God either is impossible and doesn't exist or is necessary and does exist, but what about if God is necessary and doesn't exist?

  
  

  -Malcolm poses a potential equivocation fallacy in suggesting that because God's existence is physically impossible if He cannot come into existence, then we can test this with a logical possibility test. He uses 'impossible' twice with different meanings.
• Plantinga's Ontological Argument:


  P1) God is a being who is maximally great.​

  P2) There is a possible world where a maximally great being exists.​

  P3) For a maximally great being to only exist in one world is less maximally great than a being that exists in all possible worlds.​

  C) God exists.
• Plantinga's possible worlds premises:

  A possible world is one in which nothing contradictory occurs. This is used to understand the difference between necessary, contingent, and impossible events.
• Objections to Plantinga:


  -So, first, we may accuse Plantinga of begging the question. To think that it is possible that a being that is maximally excellent exists in every possible world is already to accept that it is possible that it is necessarily true that this being exists.​

  
  

  -Second, we can object that Plantinga's definition of maximal greatness is unsatisfactory. The definition presupposes that x's greatness in a world in which x exists exceeds x's greatness in a world in which x doesn't exist. We can object that this type of comparison doesn't make sense.​