# Extending Plantinga's Ontological Argument

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The fast and dirty version of Plantinga's argument:

1)A being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W

2)A being has maximal greatness if it has maximal excellence in every possible world.

3)It is possible that there is 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, (by axiom S5) it is necessarily true that an omniscient, omnipotent and perfectly good being exists.

6)Therefore, an omniscient, omnipotent and perfectly good being exists.

Let's take a look at omniscience. Omniscience is typically defined as :"S is omniscient iff for every proposition p, if p is true then S knows p is true". It should be pointed out that Plantinga endorses a stronger version of this. For Plantinga, not only is knowing the truth value of all propositions a requirement for omniscience, but also having no false beliefs.

From here, we can search for propositions whose truth value a Maximally Excellent Being cannot know. So, we need to find a true proposition P such that "The Maximally Great Being cannot know P is true". Now, P could be anything. P could be "Buttered toast always falls buttered side down" or "Luna always has the same side facing the Earth", but there's no real reason to think that the Maximally Excellent Being cannot know that they are true (assuming, of course, that they are indeed true).

What if we try recursion? Let's let P be "The Maximally Excellent Being cannot know P is true". This has potential. Let's see if it has a clear truth value. An easy way to do this is to try an indirect proof.

1)Knowledge is "justified true belief". (there are special cases where this is not considered sufficient, but it is necessary for knowledge)

2)S is omniscient iff for every proposition p, if p is true then S knows p is true

3)Assume, for the sake of argument, "The Maximally Excellent Being cannot know P is true" is false. So, "The Maximally Excellent Being can know "The Maximally Excellent Being cannot know P is true" is true".

4)From (1), "The Maximally Excellent Being cannot know P is true" is true.

5)This contradicts our assumption that "The Maximally Excellent Being cannot know P is true" is false.

6)By indirect proof, "The Maximally Excellent Being cannot know P is true" is true.

7)Therefore, there is at least one true proposition that the Maximally Exlellent Being cannot know is true.

8)From (2), the Maximally Excellent Being is not omniscient.

Now, let's put it all together.

1)A being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W

2)A being has maximal greatness if it has maximal excellence in every possible world.

3)Therefore, if a maximally great being exists, it exists in every possible world.

4)Knowledge is "justified true belief". (there are special cases where this is not considered sufficient, but it is necessary for knowledge)

5)S is omniscient iff for every proposition p, if p is true then S knows p is true

6)Assume, for the sake of argument, "The Maximally Excellent Being cannot know P is true" is false. So, "The Maximally Excellent Being can know "The Maximally Excellent Being cannot know P is true" is true".

7)From (4), "The Maximally Excellent Being cannot know P is true" is true.

8)This contradicts our assumption that "The Maximally Excellent Being cannot know P is true" is false.

9)By indirect proof, "The Maximally Excellent Being cannot know P is true" is true.

10)Therefore, there is at least one true proposition that the Maximally Exlellent Being cannot know is true.

11)From (5), the Maximally Excellent Being is not omniscient.

12)By (1), the Maximally Excellent Being does not exist.

13)Following from (2), there is no world in which the Maximally Excellent Being exists.

14)Therefore, it is necessarily the case that the Maximally Excellent Being does not exist.

It's just some playing around. I may take the feedback here and make a more serious version for a paper or I may not; I've yet to decide.

Edited by ydoaPs

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