The Modal Ontological Argument for God's existence is logically valid

Thanks, Pro for this opportunity to explain, with a lucid partner, what is wrong with the modal ontological argument. (Quotes from Pro's post are boldfaced:) In modal logic, we infer that if some entity is logically possible then this entity is exists in some possible world. That's not an inference. It's the definition of "possible. " A maximally great being is a being with all of what we would call great making properties. That's completely arbitrary and undefined. it is self evident that it would be greater to exist in all possible worlds rather than simply just one Incoherence is not self evident. Transworld identity doesn't make sense. Plantinga says that if X exists in one world, then the closest (most nearly X-like) thing in another world is X. But there's no reason to accept that. If Jehovah exists in this world, and a rock is the closest thing to Jehovah in another world, does that make the rock into Jehovah? Does that mean Jehovah exists in both worlds? No, it means Plantinga was reduced to lame arguments. A "possible world" is one with no logical contradictions. Some possible worlds have no gods. That's not a contradiction, therefore those are possible worlds. Therefore, we know for a fact that there is no god who exists exists in all possible worlds. If another being existed in more worlds than another, then that being would be greater. That's an arbitrary claim. Whether that seems "great" depends entirely on whether you happen to like that kind of thing. Since gods seem generally nasty, I'd say the greatest god wouldn't exist in any worlds. That's not a compelling argument, but it's every bit as strong as Pro's. if a maximally great being exists in at least one possible world, then necessarily, this being exists in all possible worlds You can't infer this from the arbitrary and undefined attribute of "greatness. " Your only hope is to define "maximally great" to mean this. Doing so will give your argument much more rigor than the theists' similar arguments. Of course, that would also mean that P1 would be false, since we know there are possible worlds without gods. Such worlds are not impossible. Therefore they are possible. Therefore a god that exists in every possible world is a contradiction, an impossibility. Therefore—if you define "maximally great" as meaning that something exists in every possible world, it becomes impossible for a maximally great god to exist anywhere, in any possible world. So, since we've stipulated that a maximally great god exists in some possible world, we have precluded "maximally great" from meaning "exists in every possible world if it exists in any possible world. " Whatever else it means, it doesn't mean that, or P1 would become false. And Pro is estopped from saying that P1 is false. Therefore, we can neither define nor infer nor deduce that "maximal greatness" involves existing in every possible world. It can't happen, or P1 would be false. P1: "It is possible that a maximally great being exists. " Stipulated, for the sake of argument. P2: "If it is possible that a maximally great being exists, then a maximally great being exists in some possible world. " The definition of "possible," in possible-world-speak. P3: "If a maximally great being exists in some possible world, then it exists in every possible world. " Clearly false, given that P1 is stipulated as true. P4: "If a maximally great being exists in every possible world, then it exists in the actual world. " Yes, the actual world is possible. P5: "If a maximally great being exists in the actual world, then a maximally great being exists. " Yes. P6: "Therefore, a maximally great being exists. " This conclusion follows logically from all the preceding premises. No, either P3 is false or P1 is false. Since we have stipulated the truth of P1, it follows that P3 is false. Therefore the proof is not valid. You cannot have a valid argument in which the premises contradict each other. Parodies some people think this argument can prove the existence of a maximally great cell phone. However, a cell phone is a contingent and a maximally great being is a necessary being. Maximally great gods were invented just for the the silly modal ontological argument. If we can invent maximally great gods, we can also invent maximally great cell phones. If Pro's logic were sound, a maximally great cell phone would exist. And a maximally great everything else would exist. Want a free hamburger? Just imagine a maximally great one, and it will necessarily appear---if Pro's logic is valid. The modal ontological argument is flawed, and the parodies make this clear. Let me float my own parody: Consider Xal-X (pronounced Zal-Zee) the ascetic demon of quadratic equations. Xal-X is, by definition, existent in every possible world if he is existent in any. And he is also, by definition, logically incompatible with gods. That is, there are no gods in any possible worlds in which Xal-X exists. If a god does exist in a world with Xal-X, that is a logical contradiction, and that world is an impossible world. P1: "It is possible that Xal-X exists. " We have every bit as much reason to suppose this as we do to suppose that it is possible that a "maximally great being" exists. P2: "If it is possible that Xal-X exists, then a maximally great being exists in some possible world. " Because this is what "possible" means in possible-world speak. P3: "If Xal-X exists in some possible world, then it exists in every possible world. " We know this from the definition of Xal-X. This is what Xal-X is. P4: "If Xal-X exists in every possible world, then it exists in the actual world. " Obviously. P5: "If Xal-X exists in the actual world, then Xal-X exists. " Obviously. P6: "Therefore, Xal-X exists. " Hey, if Pro's logic is good, then my logic is good, because I'm using the same logic. P7: "Therefore, no god exists in any possible world. This follows from P6 and the definition of Xal-X. Hmm. My logic is exactly as good as Pro's logic, but we reach contradictory conclusions. Gods cannot both exist and not exist. We know, then, that there is something wrong with the logic that Pro and I have been using, the logic of the modal ontological argument. Even if we couldn't pinpoint where (though I have identified Pro's problem in P3) we would know that there was some invalidity hidden in there somewhere. We know that the modal ontological argument is invalid. We know that the resolution is false. Conclusion: The ontological argument is not valid. The resolution is false.