Descartes’ Ontological Argument

1. Descartes’ Ontological Argument Born:31 March 1596 in La Haye (now Descartes), Touraine, FranceDied:11 Feb 1650 in Stockholm, Sweden

8. Terminology of the OA Descartes was primarily concerned with God’s essence, or nature. God’s essence is described by showing his attributes, or predicates, or perfections

9. Put Descartes into context • Anselm’s 11th c. argument: • God is that than which nothing greater (more perfect) can be conceived • Ttwngcbc must exist, since an imaginary being twngcbc would be less perfect than a real being twngcbc.

11. Why was Anselm turned to stone? - because he could see into the future, and had seen the work of 14,999 A-level candidates who all wrote that his ontological argument was a “reductio ad absurdum”. Then he saw what the 15,000th candidate had written:

12. Anselm’s argument was a “rectum ad absurdum”

13. Aquinas’ rejection (13th c.) The OA only works if we know God’s essence. We do not know God’s essence. So God’s existence can be known only by our sense experience of the universe (hence Aquinas’ 5 ‘Ways’).

14. Is that true Ttwngcbc seems a reasonable place to start. Also, we could also say that we can have an ‘adequate’ idea of an all-powerful / perfect being without our having to be able to work out every single attribute that such a being would have.

15. Descartes • Assumptions: • Our senses can always deceive us • God exists to guarantee the consistency and reliability of our sense perceptions.

22. The lesson learned? • Doubt can be removed by returning to the basics. With the mind, the fact that I think gives me one fact about which I can’t be deceived – I exist: CES • So with things, to avoid deception, I must ask what is their essence – that part of a thing about which there is no argument?

23. The essence of a triangle 3 sides, 3 angles 180 degrees

24. The essence of mountains

25. The essence of God Existence Perfection Singularity In fact: every perfection

26. A 2nd stage to the argument As in Anselm II We must distinguish between ‘ordinary’ existence and ‘necessary existence’

27. Things have contingent existence

29. The same is true of ‘construct things’ like Pegasus Bellerophon riding Pegasus

30. Pegasus has ordinary existence, so like all contingent things, might not exist God must possess necessary existence, otherwise he would not be the supremely perfect being.

31. The argument reformulated tin response to Caterus • Whatever is of something’s essence must be affirmed of it: e.g. “all mammals are warm-blooded” • By definition, God’s essence is his existence • Therefore existence must be affirmed of God.

32. Objection 1: Hume Hang on, laddie, No existential statement can be analytic – they’re all synthetic

33. J.L. Mackie • “It is not simply obvious and indisputable that there cannot be analytic existential truths” • Maffs? • But maffs is logical, ‘God exists’ is a factual statement.

34. Objection 2: Kant Real predicates can’t be rejected (as with real triangles), but imaginary ones can, as with imaginary triangles and imaginary gods.

35. Yet More Kant • Moreover, sunshine, existence is not a predicate: ‘exist’ adds nothing to the subject in phrases like ‘cows exist’ • Try the effect of ‘it exists’

36. Kant once again • The same is true with describing God’s other ‘predicates’ – omnipotent, omniscient, omnibenevolent, etc., because our idea of God already contains them • So we can reject all of God’s supposed predicates

37. Kant’s swansong “The attempt to establish the existence of a supreme being by means of the … OA … is therefore so much labor and effort lost; we can no more extend our stock of [theoretical] insight by mere ideas than a merchant can better his position by adding a few noughts to his cash account.”

38. The crucial word in the OA if

39. All the OA does is to establish possibilities If God exists, then God exists necessarily, omnipotently, omnisciently, etc. The problem is that there is no guarantee that God does exist.

40. ‘Wahoo, buddy!’ – Norman Malcolm rides to the rescue ‘Ordinary’ existence is not a predicate, but ‘necessary’ existence seems as if it is. It tells you that God has to exist.

41. 1. If God came into existence now, he would be contingent, and so would not be God. 2. Therefore if God does not exist now, his existence is impossible. [why?] 3. Therefore God’s existence is either impossible or necessary.

42. 4. God’s existence can be impossible only if the concept of such a being is self-contradictory or logically absurd. 5. It isn’t, therefore God exists necessarily. 6. So in the same way, God is necessarily omnipotent and omniscient.

43. This is an analytic existential truth, in the same way that the infinity of the sequence of prime numbers (1,3,5,7,11,13 etc.) is an analytic existential truth. You either grasp this, or you don’t. Once you do, no doubt remains as to whether or not God exists.

44. Baloney, Mahoney Any competent mathematician could demonstrate the infinity of the sequence of prime numbers as a mathematical fact. It does not require intuitive understanding, only intelligence.

45. Moreover Reduce: ‘a self-contradictory notion’ to (x) And: ‘logically absurd’ to (y) And: ‘God exists’ to (z)

46. Reduce Malcolm’s argument to: not (x) + not (y) = (z) (not s.c. and not l.a. = God exists) But this equation can also be solved by: not (x) + not (y) = not (z) Not s.c. and not l.a. = God doesn’t exist

47. Malcolm – Darn it, let’s say the OA has anti-real force. This is the argument that the OA is an argument for those who believe in God. But: 1. Either the OA works or it doesn’t 2. If it doesn’t, what’s the point of believers using it?

49. Alvin Plantinga Plantinga as the cavalry: A modal version of the OA

50. Modal Logic - uses a system of possible but non-actual worlds to give a framework by which you can judge what is possible and what is necessary in the real world - it isn’t the ‘many worlds’ interpretation of quantum theory