Ontological Argument


THE ONTOLOGICAL ARGUMENT is one of the most controversial types of theistic argument.  Originally developed by the Augustinian St Anselm of Canterbury, and more recently revived by Professor Alvin Plantinga (left), the Ontological Argument is  intended to show once and for all,that the Christian God exists, with every facet of His definition included.  This includes omnipotence, omniscience, omnibenevolence, and the general term “perfection”.   To sum up the introduction, the Ontological Arguments are the apologetic ace in the hole.  An Ontological Argument shows that the existence of the concept of God, or the possibility of God, presupposes the very existence of God.


1. the branch of metaphysics that studies the nature of existence or being as such.
2. (loosely) metaphysics.

  There are several versions of the Ontological Argument out there, three of which I shall mention here, and only two of the three are valid.  Let’s start off with the invalid one, which is St Anselm’s version



  1. It is greater for a thing to exist in the mind and in reality than in the mind alone.
  2. “God” means “that than which a greater cannot be thought.”
  3. Suppose that God exists in the mind but not in reality.
  4. Then a greater than God could be thought (namely, a being that has all the qualities our thought of God has plus real existence).
  5. But this is impossible, for God is “that than which a greater cannot be thought.”
  6. Therefore God exists in the mind and in reality.

Now, this argument is at first often laughed off as a bizarre sort of riddle or joke, but then later seems to be rock-solid.  David Hume once remarked that the argument was obviously false, but that he could not for the life of him find where the fallacy lies. 

Immanuel Kant refuted the argument in five words, I think.  “Existence is not a perfection”.  The fault lies hidden in premise 4.  The key thing to note is that existence, unlike omnipotence, omniscience and perfection, is not a quality that a being posesses.  Existence itself is a thing which posesses qualities.  In short, philosophical terms, existence precedes essence (or nature, commonly: definition).  A thing must first exist before it has qualities.  

The second version of the Ontological Argument I will go over here (albeit in an unduly brief manner) is Descartes’ Version, which turns up in Descartes’ third Meditations, and which exercises the Law of Efficient Causality.  Fortunately, I believe this argument is valid and am prepared to defend it.  It must be noted though, that his version is not purely ontological, but argues from causality as it pertains to the idea of God.


  1. We have ideas of many things.
  2. These ideas must arise either from ourselves or from things outside us.
  3. One of the ideas we have is the idea of God—an infinite, all-perfect being.
  4. This idea could not have been caused by ourselves, because we know ourselves to be limited and imperfect, and no effect can be greater than its cause.
  5. Therefore, the idea must have been caused by something outside us which has nothing less than the qualities contained in the idea of God.
  6. But only God himself has those qualities.
  7. Therefore God himself must be the cause of the idea we have of him.
  8. Therefore God exists.

Now, this argument is extremely straightforward, and I have an answer to every conceivable sort of objection already planned out.  Seeing as how almost every premise can come under fire depending on who you’re talking to, I shall post none of my answers to the objections here.  I shall reply to them as they come up as comments, and post them on the appropriate Objections Page for this category of argumentation.  Rest assured that I have every reason to believe in the validity of this argument.  Every premise has been delicately scrutinized for error, though only insofar as I am able.  After all, I’m no philosopher.

The third and final version of the Ontological Argument I will go over here is the Modal Ontological Argument, which utilizes Modal Logic, or the logical understanding of possibility and necessity as they relate to existence.  This argument was made by Alvin Plantinga, as an attempt to form a successful argument that captured the purpose and style of Anselm’s argument, whilst retaining its validity.  Thus far, Plantinga appears successful in this endeavor.

A few preliminary clarificaltions must be made if the argument is to be understood by mere laymen.  When Plantinga says “possible world”, he is not referring to other possible planets like Earth, or to possible ways things could be in the future, but rather a possible world as a possible description of reality.  A coherent depiction of how things could be, is a decent definition of a possible world.  “Now in his version of the argument, Plantinga conceives of God as that which is “maximally excellent” in every possible world. Plantinga defines maximal excellence as including such qualities as omnipotence, omnibenevolence, and omniscience. A being which has maximal excellence in every possible world would have what Plantinga defines as “maximal greatness”.   


1. It is possible that a maximally great being exists.

2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.

3. If a maximally great being exists in some possible world, then it exists in every possible world.

4. If a maximally great being exists in every possible world, then it exists in the actual world.

5. If a maximally great being exists in the actual world, then a maximally great being exists.

6. Therefore, a maximally great being exists 

Premises (2)-(5) of this argument are relatively uncontroversial. Most philosophers would agree that if God’s existence is even possible, then He must exist.   And it is important to note that this is the key point of the argument.  The Modal Ontological argument shows that if God’s existence is possible, then God’s existence is real.  The principal issue to be settled with respect to Plantinga’s ontological argument is what warrant exists for thinking the key premiss “It’s possible that a maximally great being exists” to be true.

The idea of a maximally great being is intuitively a coherent idea, and so it seems plausible that such a being could exist. In order for the ontological argument to fail, the concept of a maximally great being must be incoherent, like the concept of a married bachelor. But the concept of a maximally great being doesn’t seem even remotely incoherent. This provides some prima facie warrant for thinking that it is possible that a maximally great being exists.” (William Lane Craig, www.ReasonableFaith.com)

In conclusion, I believe the two ontological arguments shown here to be valid arguments for the existence of God, but would like to add a few things.  Though Anselm’s Argument is indeed false, it might be redeemed by some unforeseen twist of logic in the future.  Until then, however, it should be considered false.  False or not though, it is highly defensible as far as lies go.  The fallacy is so craftily hidden that only someone who has memorized the refutation off of the internet or something will be able to stop you. 

You can easily use it to convince people, but only at first.  After a while, they will discover the name of the argument, as its premises will likely stick in their heads, search it on Google, and then find some summed up refutation of it off of Infidels.org or something.  This will be both the end of their faith and the end of your credibility if they do.  With that in mind, I would urge everyone to ignore the powerful attraction that I and probably you have for Anselm’s argument.  It is false,  and though I have hinted at its possible resurrection, I would caution you that this hope is dangerous.  It may lead you to using it against someone who knows the refutation.  DON’T DO THAT! 

Besides, most people will only look at you with stunned expressions, and then burst into laughter.  Most people initially see the argument as a joke.  If you push it though, they’ll stop real quick.  Use it primarily as a getaway plan, a sort of escape.  It’s definitely a debate-stopper.  It will frustrate atheists and convince agnostics of some nonsense about both sides being reasonable or what have you.  Even though they act seriously towards it in the open, on the inside, any agnostic will ponder it not as a proof, but as a joke.  Refutations will be rare, though.  This joke is 1,000 years old.  The only poeple able to refute you will be the ones who’ve “heard this joke before”.




Filed under Theistic Arguments, Theoretical Category

5 responses to “Ontological Argument

  1. Sarah

    I like all the times you say, “This is completely wrong, but here’s how to use it anyways.” Rhetorical trickery like wow! Very very informative though.

    • Andrew


      Regarding premise four of the Descartes’ semi-ontological argument, how can we verify our conception of “perfect” as perfect? Even if God, a perfect being, placed into our minds his existence, how could our minds ever comprehend perfection in the first place?

  2. Andrew


    I again want to question the validity of premise four of Descartes’ semi-ontological argument by paying special attention to the way we think of the concept of an infinite as it relates to God. Can we actually attempt to comprehend the infinity of God? Yes, we can provide our own definition of infinity, but can we really conclude that our definition matches the one that God has? If so, how can he place the concept of infinity inside the mind of a finite being? And for goodness sake, update this ghosttown of a blog! I am dying for some action here!

  3. Andrew

    Payton, or whoever will take the time to answer my question,

    While I agree that the premises of the modal ontological arguments are logically valid, I would like to question the truth value concerning the ontological status of a maximally great being.

    If we accept the premise one as it stands right now, I think the proponent of the MOA may run into some trouble. Indeed, if anyone were to accept premise one, could they not then use the logic of the ontological argument to prove the existence of all sorts of strange “perfect” entities?
    It would seem possible to ‘prove’ the existence of a super absolute evil one (a being like the traditional God in all ways except that it is absolutely evil) by a modal argument using identical logic present within Plantinga’s MOA.

    Additionally, I would like you to elaborate further on what you said in this brief paragraph:

    “The idea of a maximally great being is intuitively a coherent idea, and so it seems plausible that such a being could exist. In order for the ontological argument to fail, the concept of a maximally great being must be incoherent, like the concept of a married bachelor. But the concept of a maximally great being doesn’t seem even remotely incoherent. This provides some prima facie warrant for thinking that it is possible that a maximally great being exists.”

    This whole paragraph seems to base the coherentness of God as a concept on intuitive appeal. But is intuitive appeal really a basis in determining the validity of a concept? It seems to me that in order to make the argument work, premise 1 must be taken out of the realm of being an intuitive assumption, and the concept of the essential nature of God must somehow be logically guaranteed to be free from incompatible properties. The argument must also be such that its logic cannot be parodied to yield absurdities.

    Can you somehow construct a successful modal ontological argument that accomplishes this, or somehow explain why such intuitive appeal is justified?

  4. highschoolapologetics

    This is a good question. It does seem to me like the MOA can be parodied to yield absurdities. However, we need to be careful about this, according to Plantinga. He asks us to imagine a maximally great tortoise. In other words, an omnipotent, omniscient, perfect tortoise which exists in every possible world.

    Now, what does it take for a tortoise to be omnipotent? Shouldn’t it have massive muscles? The most massive muscles, actually. And probably psychic powers, and an organ or tool for the use of magic powers, etc… And in order for it to be omniscient, what would its brain be made out of? How big would it have to be? You get the idea.

    See, tortoises, as we know them, cannot be omniscient or omnipotent at all, or else they aren’t really tortoises. But even this is beside the point. What would the tortoise have to be in order to exist in every possible world?

    Some possible worlds are 9000 degrees Fahrenheit. Imagine what that tortoise would look like, what it would have to have, in order to exist in those conditions!

    Some possible worlds are actually anime-worlds. This tortoise would then have to be made of lines and color, and random japanese text would jump out of its mouth at random intervals!

    Then again, there is the possible world we inhabit. Is it possible for a turtle to look like anime and also like real-life? Indeed, can it also survive 9000 degree heat?

    Plantinga seems to think we need to ponder whether or not such a tortoise would actually be God, after a couple scenarios like that.

    I don’t put much stock on that answer, though. I have no idea how to answer your objection about parodies, though I’m sure Plantinga has more answers than just that.

    Anyways, on to your next question: I don’t think we need to complicate the matter with words like “intuitive”, and whatnot. The idea of Premise 1 is this:

    If X is incoherent, X cannot exist in any possible world.

    Any Y, which is coherent, must exist in some possible world.

    The idea is that a maximally great being is a coherent concept, and so, by default, it MUST exist in some possible world. Just like Hitler giving his Nuremberg address while standing on his head. That too, absolutely MUST be the case in some possible world, because it is not incoherent. That is how possible worlds work.

    Now, we can tell, simply by reason, that the idea of a maximally great being is not incoherent. None of its qualities contradict each other, and we have no problem saying that it could be the case that one exists. If that is true, then a maximally great being exists in some possible world.

    But then again, I’m not sure I follow that either. the term “maximally great” treats existence as a property, when in reality, existence is the thing which HAS the properties. This concept defeated Anselm’s Ontological Argument, and I think it may actually defeat Plantinga’s too.

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