Ontological arguments for the Existence of God

Creation_of_the_Sun_and_MoonOntological arguments for the existence of God are arguments, for the conclusion that God exists, from premises which are supposed to derive from some source other than observation of the world — e.g., from reason alone. In other words, ontological arguments are arguments from nothing but analytic, a priori and necessary premises to the conclusion that God exists.

The first, and best-known, ontological argument was proposed by St. Anselm of Canterbury in the 11th. century A.D. In his Proslogion, St. Anselm claims to derive the existence of God from the concept of a being than which no greater can be conceived. St. Anselm reasoned that, if such a being fails to exist, then a greater being — namely, a being than which no greater can be conceived, and which exists — can be conceived. But this would be absurd: nothing can be greater than a being than which no greater can be conceived. So a being than which no greater can be conceived — i.e., God — exists.

In the seventeenth century, René Descartes defended a family of similar arguments. For instance, in the Fifth Meditation, Descartes claims to provide a proof demonstrating the existence of God from the idea of a supremely perfect being. Descartes argues that there is no less contradiction in conceiving a supremely perfect being who lacks existence than there is in conceiving a triangle whose interior angles do not sum to 180 degrees. Hence, he supposes, since we do conceive a supremely perfect being — we do have the idea of a supremely perfect being — we must conclude that a supremely perfect being exists.

In the early eighteenth century, Gottfried Leibniz attempted to fill what he took to be a shortcoming in Descartes’ view. According to Leibniz, Descartes’ arguments fail unless one first shows that the idea of a supremely perfect being is coherent, or that it is possible for there to be a supremely perfect being. Leibniz argued that, since perfections are unanalysable, it is impossible to demonstrate that perfections are incompatible — and he concluded from this that all perfections can co-exist together in a single entity.

In more recent times, Kurt Gödel, Charles Hartshorne, Norman Malcolm and Alvin Plantinga have all presented much-discussed ontological arguments which bear interesting connections to the earlier arguments of St. Anselm, Descartes and Leibniz. Of these, the most interesting are those of Gödel and Plantinga; in these cases, however, it is unclear whether we should really say that these authors claim that the arguments are proofs of the existence of God.

Critiques of ontological arguments begin with Gaunilo, a contemporary of St. Anselm. Perhaps the best known criticisms of ontological arguments are due to Immanuel Kant, in his Critique of Pure Reason. Most famously, Kant claims that ontological arguments are vitiated by their reliance upon the implicit assumption that “existence” is a predicate. However, as Bertrand Russell observed, it is much easier to be persuaded that ontological arguments are no good than it is to say exactly what is wrong with them. This helps to explain why ontological arguments have fascinated philosophers for almost a thousand years.

Anselm’s Argument, its history and critisism.

Anselm’s original argument

Anselm presents the ontological argument as part of a prayer directed to God. He starts with a definition of God, or a necessary assumption about the nature of God, or perhaps both.

“Now we believe that [the Lord] is something than which nothing greater can be imagined.”

Then Anselm asks the big question – does God exist?

“Then is there no such nature, since the fool has said in his heart: God is not?”

To answer this, first he tries to show that God exists ‘in the understanding’:

“But certainly this same fool, when he hears this very thing that I am saying – something than which nothing greater can be imagined – understands what he hears; and what he understands is in his understanding, even if he does not understand that it is. For it is one thing for a thing to be in the understanding and another to understand that a thing is.”

Anselm goes on to justify his assumption, using the analogy of a painter:

“For when a painter imagines beforehand what he is going to make, he has in his undertanding what he has not yet made but he does not yet understand that it is. But when he has already painted it, he both has in his understanding what he has already painted and understands that it is. Therefore even the fool is bound to agree that there is at least in the understanding something than which nothing greater can be imagined, because when he hears this he understands it, and whatever is understood is in the understanding.”

Now Anselm introduces another assumption:

“And certainly that than which a greater cannot be imagined cannot be in the understanding alone. For if it is at least in the understanding alone, it can be imagined to be in reality too, which is greater.”

Example: Most people would prefer a real £100 as opposed to an imaginary £100

“Therefore if that than which a greater cannot be imagined is in the understanding alone, that very thing than which a greater cannot be imagined is something than which a greater can be imagined. But certainly this cannot be.”

Anselm’s found a contradiction! From that contradiction, he draws his conclusion:

“There exists, therefore, beyond doubt something than which a greater cannot be imagined, both in the understanding and in reality.”

A modern description of the argument

In order to understand the place this argument has in the history of philosophy, it is important to understand the essence of the argument as Anselm first conceived it.

A key to understand the ontological argument is understanding the idea of “perfections.”

There are various kinds of so-called perfections. Size, intelligence, beauty, power, benevolence, and so forth — all these qualities are called perfections. And there are various degrees of these perfections. What is more intelligent is more perfect as regards intelligence; what is more beautiful is more perfect as regards beauty; and so forth.

Short and very general description of the ontological argument.

Anselm, and many others, define God as the perfect being. This means that he has all the perfections to the greatest conceivable degree. Indeed it seems that all of the monotheistic religions make the claim that there is nothing greater than God.

In fact, Anselm would say if someone were ever to conceive of some greater degree of perfection, than he or she previously conceived of, then they must regard God as having that greater degree of perfection.

According to Anselm this proves that God exists, since claiming that God is only imaginary entails a logical contradiction. To see why this is so take a look at these two propositions.

  • 1) Someone has a concept of the greatest conceivable being, which they call God.
  • 2) This concept of God as the greatest conceivable being exists only in his or her mind.

St. Anselm says that these two propositions contradict each other because for both 1 and 2 to be true, the following must also be true:

  • A) It is possible to have an idea of the greatest conceivable being.
  • B) And that this most perfect conceivable being is just imaginary.

But in that case the idea of God is as a being that is only imaginary; so it is not a concept of the greatest conceivable being, because a being that actually exists is a greater being, more perfect, than a being that merely exists in only in the imagination. Existence is a perfection, just like power, beauty, and so forth. So, the concept of the greatest conceivable being, must be a concept of a being that actually exists. A being that didn’t exist wouldn’t be the greatest conceivable being.

That means that the second proposition, that the concept of God exists only in our minds, contradicts the first proposition, that we have a concept of God.

This leads to Anselm’s conclusion that if someone has a concept of God, then God necessarily exists. Since it is impossible to deny the first proposition, because many people do seem to have a concept of God as the most perfect being, the only solution is to throw out 2.

Critiques and Objections

Gaunilo’s Island

One of the earliest recorded objections to Anselm’s argument was raised by one of Anselm’s contemporaries, Gaunilo. Gaunilo invited his readers to think of the greatest, or most perfect, conceivable island. As a matter of fact, it is likely that no such island actually exists. However, his argument would then say that we aren’t thinking of the greatest conceivable island, because the greatest conceivable island would exist, as well as having all those other desirable properties. Since we can conceive of this greatest or most perfect conceivable island, then it must exist. While this argument seems absurd, Gaunilo claims that it is no more so than Anselm’s.

Defenders of Anselm’s argument answered that the idea of an island does not include the notion of perfection, the perfection is merely tacked on, while the concept of God cannot be separated from the notion of perfection. This explains their claim that there is an explanation for the failure of Gaunilo’s argument — namely the fact that the island’s perfection is contingent — which doesn’t affect the Ontological Argument.

Necessary Nonexistence

It can be argued that nonexistence is greater and more perfect than existence. The elements of existence are asymmetric and interact because of their imperfections. If they were perfect they would be static. Nonexistence is boundless, timeless, omnipresent, simple, etc. Existence is defined by its limitations. Furthermore, for any number of things that exists, one can imagine twice as many that do not exist, or the set of all sets of them, etc.

Another rationale is attributed to Melbourne philosopher Douglas Gasking (1911-1994), one component of his proof of the nonexistence of God:

  • The creation of the world is the most marvelous achievement imaginable.
  • The merit of an achievement is the product of (a) its intrinsic quality, and (b) the ability of its creator.
  • The greater the disability (or handicap) of the creator, the more impressive the achievement.
  • The most formidable handicap for a creator would be non-existence.
  • Therefore if we suppose that the universe is the product of an existent creator we can conceive a greater being — namely, one who created everything while not existing.
  • Therefore God does not exist.

 (Reference: Gasking’s Proof’, Analysis Vol 60, No 4 (2000), pp. 368-70.)

Gasking was apparently thinking the “world” or “universe” is the same as “everything.” The proof is strengthened if “everything” is substituted. However, defenders of Anselm would reject the thesis that disability and handicap are things that make a creator greater.

Existence as a property

Another traditional criticism of the argument is that existence is not a perfection, because existence is not a property as such, and that referring to it as a property confuses the distinction between a concept of something and the thing itself. The argument is that anything which has the “property” of being non-existant could not possibly have any other properties, being non-existant, and thus not having color, location, or any other property. One cannot, the argument says, speak meaningfully of the non-existant apple that one is holding, saying that it is red, crisp, weighs a certain amount, is in one’s right hand, and does not exist. Another way of phrasing this is that, if existence is a property, then there exist a number of things that have the property of not existing – a statement which is rejected as patent nonsense. This objection is rejected by some because it is seen as having other undesirable consequences.


A fourth criticism of Anselm’s argument rests on the claim that, even if existence is a property, it is still not a perfection because existence is either true or false while degree of perfection is a continuous scale. Defenders of the ontological argument have replied to this objection that its conclusion does not follow from its premise.

A fifth criticism is that the choice of “God” as the term for the perfect being is misleading, and invites the reader to substitute a particular culturally-determined deity for the perfect being used in the argument. This criticism does not directly contradict the validity of the argument but instead suggests that using the ontological argument to demonstrate the existence of a particular deity involves a fallacy of equivocation.


Obviously Anselm thought this argument was valid and persuasive, and it still has occasional defenders, but many, perhaps most, contemporary philosophers believe that the ontological argument, at least as Anselm articulated it, does not stand up to strict logical scrutiny.

Some of those who have argued that the ontological argument fails are content to leave it at that, either because they do not believe that God exists, or because they believe the existence of God is demonstrated on other grounds. Others, like Kurt Gödel, Charles Hartshorne, Gottfried Leibniz, and Alvin Plantinga have reformulated the argument in an attempt to revive it.

Commentaries by other philosophers:


And how does the God’s existence emerge from the proof? Does it follow straightway, without any breach of continuity? Or have we not here an analogy to the behavior of the little Cartesian dolls? As soon as I let go of the doll it stands on its head. As soon as I let it go — I must therefore let it go. So also with the proof. As long as I keep my hold on the proof, i.e., continue to demonstrate, the existence does not come out, if for no other reason than that I am engaged in proving it; but when I let the proof go, the existence is there. But this act of letting go is surely also something; it is indeed a contribution of mine. Must not this also be taken into the account, this little moment, brief as it may be — it need not be long, for it is a leap. However brief this moment, if only an instantaneous now, this “now” must be included in the reckoning. (In: Philosophical Fragments, Swenson, p. 32)

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