[QUOTE=begbert2]
Ah, the actual proof! Okay: I reject both of these premises. You have instantiated this variable ‘God’ to represent a thing that Exists (in some possible world) and has the property of being Necessary (in all possible worlds). Now, it’s not hard to find things that Exist, and it’s not hard to imagine something that is Necessary, but how can you possibly have determined that you have found an actual real Existent thing that is also Necessary?
[/QUOTE]
You are free, of course, to reject either premise. But let me make it plain just exactly what it is that you are rejecting.
Just as belief in X is not the same as the existence of X (a doxastic issue and an ontological issue respectively), so it is true that the definition of X is not the same as the proof of X (a linguistic issue and a logic issue, respectively). In other words, we cannot define things into existence. Otherwise, I could prove that pigs fly by defining “fly” to mean “wallow in mud”.
Part of the confusion I’ve seen in the modal ontological proof is that people (not logicians, but lay observers) confuse the definition of God as necessary existence with the logical inference that God exists necessarily. That’s because they are symbologically identical — G. But it is one thing to say that God is necessary existence, and quite another to say that something implies that His existence is necessary.
Definitions are not themselves logical propositions. For a proposition to be logical, it must follow by inference from some other logical proposition. (This is the K, or Kripke, rule of logic.) This rule effectively closes a logical proof off from everything but the premises and inferences. The first statement in any nontrivial proof is always a premise, which is an unproved assertion. Since it comes first, it obviously cannot have followed from something else, and so premises must be chosen carefully. A ridiculous premise will be rejected out of hand by most examiners.
Once the premises have all been stated, the proof gets underway in earnest. The only way a statement can follow the premise section is by application of the rules of logic. Introduction of a premise later is called “audiatur et altera pars” and, while not a logical fallacy per se, disrupts the flow of the proof and can even mislead interpretation. So, once you’ve had your say axiom-wise, everything that follows must follow the rules. Whenever a rule is misapplied, the proof is said to be “invalid”. But if all rules are rightly applied, then the proof is said to be “valid”. (Note that a proof may be valid even if its premises are false.)
Each step in the proof after the premises is called an “inference”, and is necessarily a logical proposition — not a definition, and not a premise. Thus, if G follows from the statement before it by some rule of logic, then G in that context is a logical proposition, and not a definition. Moreover, if the rule of logic was not misapplied, then the proposition is a valid one.
The final inference in a proof is called the “conclusion”. The conclusion should match identically what it was you were to prove. But it cannot match any of your premises, because that would make it “circulus in demonstrando”; i.e., it would be begging the question — you will have assumed your conclusion before your examination even began.
Therefore, although God is defined as necessary existence, that means nothing proof-wise. It’s fine to define something, but until a statement about the thing has followed from some other statement that is itself valid, then all you have is an unproven thing. Thus, G as a logical proposition is true, while G as a definition has no truth value of any kind, neither true nor false.
Now, with respect to the definition itself, it corresponds directly to the traditional notion of God as supreme being. Supremacy is a superlative concept — like most, or best, or X-est — implying uniqueness and greatest magnitude; otherwise, it would just be superior — more, better, or X-er. Since there can be no existence greater in magnitude than existence in every possible world (impossible worlds don’t exist), and since “being” is itself an ontological statement, it seems reasonable to characterize the supreme being as having ontological supremacy. And that’s exactly what necessary existence is. And so, supreme being maps perfectly to necessary existence. Supreme -> necessary / being -> existence.
So when you reject the first premise — it is possible that God exists — you are rejecting something quite specific. Now, it depends on what you negate with your rejection, whether it be the possibility (a negation of the modal) or the God (a negation of the term). In other words, these are two different statements: (1) it is not possible that God exists; and (2) it is possible that God does not exist. But either way, substituting the definition for the term (which obviously is reasonable) reveals that rejection of the premise is basically nonsense. Either (1) it is not possible that that which exists in every possible world exists; or (2) it is possible that that which exists in every possible world does not exist. It is tantamount to rejecting the existence of the actual world. There is nothing unreasonable about allowing for the possibility that God exists.
And when you reject the second premise — if God does exist, then He exists necessarily — you are invoking a contradiction. Again, by substitution, you are saying that if that which exists in every possible world does exist, then that which exists in every possible world does not exist in every possible world.
I do not envy the person who must defend either of those counter-premises.
). He is making god necessary without proving that it exists outside his mind. Again, that’s fine, but it has no effect on my or anyone else’s world. Until he clears up that problem, the entire exercise is pointless. In effect, he’s saying we all live in our own reality; a concept that I believe to be true to a large extent. But in the physical world, part of our realities overlap, but the god presence can never exist outside a believer’s mind.
