Thursday, February 16, 2012

Testing the Ontological Argument

I was speaking with a friend last night who was not very familiar with the modal ontological argument, and I decided to try something. I wanted to see how the argument would go over if I explained, in detail, each premise, to someone who was not already familiar with it. While there was undoubtedly some bumps in the road, I nevertheless felt that my particular view of it was vindicated: unless someone can show incoherency in the concept of a maximally-great being (MGB), then one is justified in affirming he exists. The following is an outline of our conversation, with occasional comments.

1. Possibly, MGB exists.
1a. An MGB is one who possesses all great-making properties.
1b. A great-making property is one that is better to have than to lack, for any being.
1c. The great-making property must be taken in a maximal way (i.e., knowledge of all propositions, or omniscience).
1d. One can affirm this possibility if he has at least one great-making property taken in a maximal way that it seems at least possibly exemplified, or if there is no incoherence in such a concept.

One who isn't already familiar with the argument, as my friend was not last night, will probably accept all of the above.

2. If possibly, MGB exists, then MGB exists in at least one possible world.
2a. A possible world is a maximal description of the way reality could be, encompassing all propositions or their negations in a consistent way.
2b. Anything that is possible, then, exists in a possible world.

Again, this should be uncontroversial for the hearer.

3. If MGB exists in a possible world, then MGB exists in all possible worlds.
3a. If any P is a great-making property, then MGB possesses it (from 1a).
3b. Necessary existence is a great-making property.
3c. Therefore, MGB possesses it.
3d. Necessary existence entails existence across all possible worlds.

4. If MGB exists in all possible worlds, then MGB exists in the actual world.
4a. The actual world is a possible world, else it would be impossible.

5. Therefore, the MGB exists in the actual world.
5a. Whatever is actual exists in reality.

6. Therefore, the MGB exists.
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  1. I think 2a is where it goes wrong. A possible world is a singular way reality could be. It does not include modalities, which require a set of possible worlds.

    Self-promotion: a more detailed working here:

  2. Hi Tony. :) I'm a bit confused by your objection, as (2a) is just the usual account of possible world semantics. I'm using "the way reality could be" to be synonymous with "state of affairs of reality," and thus it is a complete (full, or maximal) state of affairs of how reality could be. In any case, it should be uncontroversial that whatever is in a possible world is possible, and that if MGB is possible, it is in at least one possible world.

  3. A maximally great being is thought of all-loving, but is there a maximal degree of love? No matter how much God loves his creatures, can't we conceive of him loving them even more?

  4. Hey Kyle. :) It doesn't have to be "degree," but just a great-making property taken in a maximal way (which may or may not involve degrees). I think being loving in a maximal way entails that a) there is someone or something to love (implied Trinity argument, anyone?), and b) that for every other being X, X is loved by the all-loving being. So it's not that he loves to Y degree, or loves Z number of people, but that he loves everyone; there is no one he does not love. And love personally. I think that may well entail omniscience, for how can you love someone personally without knowing them? I can love humanity in general and feel love for the unsaved in Africa, but I cannot love a specific person in Africa in that scenario, for I know no one.


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