The Ontological Argument for the Existence of God

[Angrboda]

Here are the two definitions Plantinga starts with

[*]A being is maximally excellent in a world W if and only if it is omnipotent, omniscient, and morally perfect in W; and
[*]A being is maximally great in a world W if and only if it is maximally excellent in every possible world.

Given these two definitions, the argument is constructed:

1. The concept of a maximally great being is self-consistent.
2. If 1, then there is at least one logically possible world in which a maximally great being exists.

Two doesn't follow from one.  One only states that the concept of a maximally great being is coherent, not that it is instantiated in one or more possible worlds.  I can only assume you've misstated the argument as I can't imagine Plantinga making such a bonehead mistake.  You go on to state that there are no "holes" in the argument, despite this glaring one.  Nice try but bluster doesn't substitute for logic.

If this is indeed Plantinga's argument, then more silliness follows. As noted, a maximally great leprichaun would also be self-consistent and necessary. If all that is required for the rest to follow (number two onward) is that the entity be necessary and self-consistent, then a necessary unicorn also follows. A necessary anything can be plugged into the argument and as long as the concept is "logically self-consistent" then it must in actuality exist according to this argument. I first noticed this in an earlier incarnation of Plantinga's argument when I noticed that you could substitute a necessarily existing universe in place of his necessary "being". You can substitute an infinite number of things.

I think this simply shows at bottom how easy it is to conflate Lewis' possible world semantics with other notions of possibility. A classic example of the use of possible world semantics is to evaluate the concept of free will. In this example, one is given the hypothetical that one has just attempted to make a putt in golf and missed. There are "possible worlds" that differ only slightly from the real world where you would have made that putt. But lets take a possible world in which the ball and the hole are in separate dimensions (or in other words in separate time-space continua, or branes in the language of physics). Let's suppose that brane theory is wrong and there are no "other dimensions" for the hole to sit in. There is nothing logically incoherent about the ball and hole being in different dimensions, so there is a logically possible world in which that happens. But if there is only one set of dimensions, is it "possible" in the real world sense for the hole and the ball to be in separate dimensions? No, it is not. There is a difference between logically possible worlds and real existent worlds. And Plantinga trades on this ambiguity. He starts out addressing logically possible worlds and elides into suggesting that this logically possible world exists. It doesn't necessarily, possible worlds semantics is a tool for generating hypotheticals, and not all logically possible hypotheticals are real world hypotheticals. For this maximally great being to actually exist, it has to exist in some real world hypothetical, not just a logically consistent hypothetical. For at bottom a hypothetical is just an idea of something, not a real thing. This curiously brings us back to Anselm who was trying to elide the same mistake, confusing an idea of a maximally great being with a real, reified thing that has properties such as 'existence' (if existence be a property). At the end, all Anselm has is the idea of something existing actually being real, with the question of whether there is a real world example of that idea that exists correspondingly.