Possibility = Necessity

Is it possible that God (i.e., Anselm’s Greatest Conceivable Being) exists in some possible world (a possible world being the way reality might be)?

In Christ,

I would caution you as to your formulation of Anselm’s argument. He did not call God “the greatest conceivable being,” but “that of which nothing greater can be conceived.” I realize the language sounds similar here, but make sure that you are using his wording and meaning or you run the risk of being misunderstood. His argument is already hard enough to understand, and is frequently misstated and argued against–although those who argue against it oftentimes get it wrong and argue against something completely different.


Could you enlighten me as to the difference in meaning–according to Anselm’s usage of the terms, as well as the substance and aim of his argument–between “the greatest conceivable being” and “that of which nothing greater can be conceived”?

I see no need for “caution” here, seeing that Anselm understood by “that of which nothing greater can be conceived” to be God, i.e., the greatest conceivable being/thing, the maximally great being, etc. All of these are used by philosophers to describe and set forth the ontological argument; the reason being: they are functionally equivalent terms.

I agree that a greatest conceivable being and “that of which nothing greater can be conceived” are functionally equivalent.

The question of if a greatest conceivable being or (in Plantinga’s formulation of the argument) a Maximally Excellent Being exists in any possible world is a great question. The hard part is showing if it is possible though. One thing that could make us think it’s possible is simply the fact that the concept of an MEB is a coherent concept (unlike the concept of a married bachelor, which is an incoherent concept). Saying “An MEB exists” however, does not seem like saying “a married bachelor exists,” so that gives us at least some reason for thinking that it is possible that an MEB exists.

Moreover, I have not yet set forth a formulation of Anselm’s argument. I was planning on doing so once I received a few responses affirming the obvious possibility of the existence of the greatest conceivable/maximal being/thing in some possible world.

Here is Anselm’s argument:
**(P1) **GCT=the greatest conceivable thing
(P2) We understand GCT
(P3) GCT exists in the understanding (i.e. we have an idea of GCT)
Assume for reductio ad absurdum that:
**(P4) **GCT does not exist in reality, but only in the understanding
**(P5) **We conceive that it is greater to exist in reality than in the understanding alone
But then, from (P4) and (P5):
(P6) We can conceive of something greater than GCT, namely, something just like GCT, except that it exists in reality as well as in the understanding
But (P6) contradicts our definition of GCT in (P1).
So our assumption for reductio ad absurdum (P4) must be false, i.e.:

**© **GCT does exist in reality

My purpose in first asking the question of whether it is possible for GCT to exist in some possible world was to establish it as a true possibility, and then reason as follows (according to Plantinga’s reformulation of the ontological argument):

(P1) It is possible that a maximally great being exists
(P2) If it is possible that a maximally great being exists, then it exists in some possible world
(P3) If a maximally great being exists in some possible world, then it exists in every possible world
**(P4) **If a maximally great being exists in every possible world, then it exists in the actual world
(P5) If a maximally great being exists in the actual world, then a maximally great being exists
© Therefore, a maximally great being exists

In sum, by conceding to the *possibility *of the existence of a maximally great being (God), one is logically compelled to conclude the actuality of the existence of this maximally great being.

Thus the skeptic must defend the impossible argument that God’s existence is *not even possible *in order to avoid the conclusion that God’s existence is actual.

(Of course, I am aware that this argument does not provide us with any description of the maximally great being, that is, the argument does not prove the existence of the Judeo-Christian God; it does, however, prove the existence of a maximally great being/greatest conceivable thing, which is properly called god. Further arguments are then required to describe God as the God of Jesus Christ–historical arguments for Christ’s resurrection in particular).

In Christ,

There are no possible worlds that G-d does not exist in. As Aquinas pointed out the the substance of G-d must necessarily be existence itself. Therefore a world without G-d would lack existence and hence not be a possible world.

I agree. The entire argument rests on the premise of whether or not it is possible for God to exist. I find there to be both intuitive and *a posteriori *warrant for concluding it to be true.

First of all, it is intuitively coherent. For the argument to be invalid, (P1) would have to be intuitively incoherent.

Second, there is the conceptualist’s argument for God’s existence:

(P1) Abstract objects, such as numbers and propositions, are either independently existing realities or else concepts in some mind
**(P2) **Abstract objects are not independently existing realities
(P3) If abstract objects are concepts in some mind, then an omniscient, metaphysical necessary being exists
**© **Therefore, an omniscient, metaphysically necessary being exists

Furthermore, we have Leibniz’s Principle of Sufficient Reason, which holds that there must be a reason or rational explanation for the existence of one state of affairs rather than another. The question, “Why is there something rather than nothing?” can, in light of the principle that “nothing happens without a sufficient reason” must be found outside of the universe, in a being who is Self-Sufficient, i.e., a being that is its own Sufficient Reason. This lends–I believe–strong rational support for the possibility of God’s existence.

In Christ,

I agree with you. But, in terms of logical argument, if we argue that God exists because God is existence itself, then we are question begging. I am trying to use Anselm’s ontological argument, as well as Plantinga’s reformulation of it, to show that God necessarily exists based upon the high degree of plausibility for His possible existence.

In Christ,

What are your thoughts on whether there can be a posteriori warrant for the first premise? I can buy that there is some a priori warrant for it, but what about a posteriori?

I ask because the argument requires being able to show that it is possible that God exists. But can another argument do that? If the argument is successful, then it will show that God exists. If it is not, then it cannot show that it is possible that God exists. I waver on this point, but wonder what your thoughts are.

Excellent. I see that you are also a fan of Fr. Copleston. Me too. Not to derail the thread, but want to point out that I don’t argue that G-d exists because He is existence, that would be begging the question. Rather, I argue that there is no alternative to the act of existing because the alternative to existence, an existent nothing, is a logical contradiction. There is simply no logically valid alternative to the act of existing, which Aquinas defined as G-d. Good luck. If I think of anything pertinent, I will post it.:slight_smile:

Excellent blog you got there.


I would assert that both the cosmological and teleological arguments for God’s existence provide sound a posteriori reasons for believing that God actually exists, and provide near certain support for the premise that God possibly exists.

The entire ontological argument rests upon the first premise. The theist need only show the possibility of God’s existence (a very weak claim), whereas the atheist needs to show that God cannot possibly exist (a very strong claim). The matter will ultimately come down to abductive inference, i.e., inference to the best and most probable explanation. In light of the aforesaid intuitive and *a posteriori *arguments for God’s existence, I would say that the proposition, “It is possible that a maximally great being exists” is far more probable than its negation.

In Christ,

If you mean whether it’s possible epistemically that Anselm’s GCB exists in some possible world, then I suppose so. Whether it’s metaphysically possible is another question, and it’s kind of hard for me to say.

Atheist = “lack of belief/disbelief in god” NOT “god does NOT exist.” Could it not be possible that a multitude of other ideas also exist?

It could be. But those ideas do not entail their existence. We have to make a distinction here between “possible” in the epistemic sense, and “possible” in the metaphysical sense. Possible in the epistemic sense just means “for all we know”. For instance, for all we know there could be aliens. It is possible in that sense. There’s another version of possibility which has to do with whether the concepts are really coherent or not. This is the metaphysical sense. For instance, it’s not possible metaphysically for a circle to be square.

If God’s existence is metaphysically possible, then, by the rules of (modal) logic, it would follow that he exists necessarily. Now, certainly God’s existence is epistemically possible, that is, for all we know he could exist. But whether his existence is metaphysically possible is harder to determine. But if the atheist were to admit God’s metaphysical possibility, it would follow that they must admit his necessity and real existence.

I understand the differences in the two senses you describe. My question now is why could aliens not also be asked in a metaphysical sense. The circle/square example was self-refuting so I understand that, but are aliens self-refuting? So my question is in your 2nd paragraph, what makes the argument incorrect by replacing the word god for aliens?

Part of the traits of God, a “Maximally excellent being” is necessary existence, hence He exists in every possible world. The existence of aliens is possible, but because they do not exist necessarily, they do not exist in every possible world, hence do not necessarily exist in this world. As an MEB God exists in every possible world, hence in this world.

As the person above me said, the very nature of God is that it is a necessary being. A necessary being is a being which exists in all possible worlds. Aliens on the other hand are contingent beings, that is, they are beings which exist in some possible worlds and do not exist in others. So if we prove that aliens are metaphysically possible, we’ve only proven that they exist in some possible worlds and do not exist in others. God on the other hand is a being which if he exists, then he exists in all possible worlds. So if he exists in one possible world, then he exists in all possible worlds, and hence exists in the actual world (which is a possible world). Hope that’s not too confusing. :wink:

I was not attempting to define atheism; I was demonstrating the consequences of what the argument asserts, and what therefore needs to be proven or disproven by both parties (theists and atheists).

If it is probable that God possibly exists in some possible world, then it is probable that God exists in our world. Hence, the title of the thread “Possibility = Necessity”

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