h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Great Stuff!

I'm very impressed with Alvin Plantings'a version of the OA myself. I'm writing form memory here, but as I remember it goes like this:

1: It is accepted by philosophers that there is an infinity of possible worlds (though only one is actual).

2: All possibilities are played out in these possible worlds.

3: Therefore the supreme concievable being must exist in some of these worlds.

4: But we can concieve of the supreme concievable being existing in all of these possible worlds.

5: If the supreme possible being, already proven to exist in some of these worlds, only exists in those worlds, it is not the supreme concievable being.

6: Therefore this being must exist in all possible worlds.

7: Given that all possible worlds includes the actual one, this being must exist in the actual one (eg ours).

8: Therefore God exists.

As a hardened Agnostic this argument frightens me, because I'm not aware of any successful refutation of it. It does not convince me, of course, but I can't for the life of me see that there's anything wrong with it.

I can't say that I've come across his version of the OA before, but it is interesting!
My personal favourite is Descartes' version, because it is so concise and precise. Also, it is more positive in character than Anselm's one.
I've done a search for Plantinga's OA and put a link in under 'Further Reading'.

Something that you might be interested in is in the Philosophers magazine (see the link in the entry), there is a game called 'Battleground God' where you get a number of questions on your beliefs which soon exposes any fallacies in one's reasoning. It's quite hard to survive if you are a believer.

I did pretty well

I bit one bullet, because I take my scepticism to Humean proportions, so it thought my answers were odd. And I took a direct hit bacause I assumed that the logically impossible was left out of the caoncept of omniopotence. So I enjoyed that, thanx for telling me about it.

No problem! Usually, I get by with either biting one bullet (on a good day!) or one direct hit and one bullet.

I got to bite two bullets, but no direct hits.

Don't worry Leg, Plantinga's OA goes down like a lead canoe just like all the others.
Point 2. Do all the possible worlds play by the same RULES as ours?
If yes, then point 3 only follows on the assumption that the rules of our possible world allow for the actual existence of such a being, but this is not shown.
If no, why should contradictory rules on another possible world have anything to do with what is possible in ours?
I've seen another version of the OA from Plantinga but it founders in exactly the same way!
Besides, what sort of necessity are we talking about? What establishes it? Nary a word from the supporters of OA on that one, eh?