# Ontological argument



## T.A.G. (Dec 13, 2009)

My text book went through different arguments for God's existence such as the argument from nature which was developed by Paley as well as the argument known as the First Cause Argument, they presented these and their problems very well. It presented the ontological argument in a very confusing way though. Can anyone else help explain it and the problems people have with it?


----------



## Reformed Thomist (Dec 13, 2009)

Breakdown of Anselm of Canterbury's Ontological Argument (the classic O.A., from the _Proslogion_, of which the arguments of Descartes and Spinoza are variations):

1. *God is “something than which nothing greater can be thought.”*

2. *This nature exists in the mind.* Even when someone (the Fool of the Psalms) denies the existence of God, that nature must exist in his mind.

2.1. The Fool hears the words “that than which nothing greater can be thought” (=NGT)
2.2. In order to deny the existence of _x_, _x_ must be *understood* when heard.
2.3. The Fool denies the existence of NGT.
2.4. Therefore NGT is understood by the Fool.
2.5. Whatever is understood _exists_ in the mind of the hearer.
2.6. Therefore, NGT _exists in the mind of the Fool_.

3. *Existence in the mind and existence in reality are distinct:*

3.1. When a painter contemplates the design he is about to paint, it _exists in his mind_.
3.2. But prior to its execution, this idea is _not understood to be_.
3.3. If the painter contemplates the same design _after_ he has painted the picture, he now understands it _as something really existent_: *it is understood to be*.
3.4. Therefore, the human mind can and does distinguish *between its own ideas taken simply as ideas*, and its ideas as *representative* of things that are real and existent.
3.5. Whatever the mind can compare, it can rank and order.
3.6. Thus our mind can compare the ideas of something as existent in reality, and as existent in the mind alone, and can rank one—the existent—as greater than the other.

4. “That than which nothing greater can be thought” (NGT) cannot exist in the mind alone.
*Reductio ad absurdum argument:*
4.1. Assume that the idea, NGT, exists in the mind alone.
4.2. Then NGT can also be thought to exist in reality as well. (This is what the painting analogy shows: it is possible for something to exist in the mind alone, in reality alone; or in both mind and reality).
4.3. But to exist in reality and in the mind is greater than to exist in the mind alone.
4.4. Thus, if “that than which nothing greater can be thought” exists only in the mind, then “that than which nothing greater can be thought” is not really “that than which nothing greater can be thought,” since a greater can be thought, namely, this same nature as existent in reality.
4.5. This is a contradiction, and thus completes the _reductio_. A NGT that exists in the mind alone is not a NGT.

5. *Therefore, God exists*.

---------------------------------------------------

Now the problem with Anselm's argument, as I see it, is that the finite mind _cannot_ grasp the nature/essence/quiddity of God (premise 2); to grasp the infinite is beyond the ability of the finite. And if the Fool could/did actually understand God's essence he would/could have no doubt of God's existence, for God's existence is certainly contained in His essence: existence or being is a fundamental fact about God. For him to 'reject' God's existence tells us that he really does not/could not really grasp God's essence. So, fundamentally, Anselm's error is in ascribing to the human mind a power beyond its ability. (We will, of course, have a vision of God's essence when we receive the beatific vision in Heaven, but we cannot do so _here_.)


----------



## Ask Mr. Religion (Dec 13, 2009)

Plantinga's variation of the ontological argument:

1. It is proposed that a being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W; and
2. It is proposed that a being has maximal greatness if it has maximal excellence in every possible world.
3. Maximal greatness is possibly exemplified. That is, it is possible that there be a being that has maximal greatness. (Premise)
4. Therefore, possibly it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
5. Therefore, it is necessarily true that an omniscient, omnipotent and perfectly good being exists. (By axiom S5 from modal logic)
6. Therefore, an omniscient, omnipotent and perfectly good being exists.

Note: Axiom S5 is the distinctive axiom of the S5 system of modal logic and says that if possibly necessarily p, then necessarily p. If the modality here is what Alvin Plantinga calls "broadly logical" necessity and possibility, then an argument for the axiom can be given as follows. If possibly necessarily p, then there is a possible world w at which p necessarily holds. Then, it is true at w that p is a broadly logically necessary truth, something whose negation would in a broadly logical sense be self-contradictory. But if something is self-contradictory at some possible world, then it is self-contradictory at all worlds, and Plantinga holds that this is true even in the case of broadly logical self-contradictions as well.

AMR


----------



## Philip (Dec 13, 2009)

A version of the ontological argument that I have used:

1) God is the greatest possible being
2) God exists either contingently or necessarily
3a) *God exists contingently*
3b) Necessary existence (existence in all possible worlds) is an absolute great-making property
3c) There is a possible being just like God who has necessary existence
3d) This being is therefore greater than God
3e) Therefore there is a possible being greater than the greatest possible being
3f) 3e is contradictory
4) *Therefore God necessarily exists*
5) That which necessarily exists exists necessarily
6) God exists

This argument doesn't suffer from the criticisms of Plantinga's argument. The only real weak spot is that it relies on the intuition that necessary existence is an absolute great-making property.

Also, Nathan, you misunderstand Anselm's argument--it does not depend on human comprehension. God is the greatest being conceivable by _any_ being--including God. The fool understands that what we mean by God is the greatest conceivable being--that's what Anselm meant by saying that God exists in the mind--we can conceive of God, to an extent.


----------



## kevin.carroll (Dec 14, 2009)

The ontological argument bends the mind a bit. It says that God is greater than anything we can imagine. We can imagine God's existence. Since actual existence is greater than imagined existence, God must exist or else he would not be greater than our imagination. (This argument requires a pipe, an adult beverage, and a great deal of time to sink in.)


----------



## Zenas (Dec 14, 2009)

*clings to his Van Til and rocks back and forth slowly.*


----------



## Philip (Dec 14, 2009)

Zenas said:


> *clings to his Van Til and rocks back and forth slowly.*



My understanding is that Van Til's transcendental argument is just a modal ontological argument in reverse.


----------

