Anselm of Canterbury was a medieval monk and archbishop who made important contributions to philosophy and philosophical theology apart from his most famous contribution: the ontological argument, found in his Proslogion. The ontological argument is controversial for a number of possible reasons. It might simply be controversial because, if successful, it would be the most logically coercive argument that God exists. The argument literally implies that it is logically necessary that God exists, or, it is logically impossible that God does not exist. This means it is not surprising that the argument would make people who do not believe in a traditional God pretty uncomfortable. Alternatively, the argument might be controversial because it doesn’t feel compelling to its hearers. There is probably some tendency to think that, when heard, the ontological argument has subjected its hearer to a sort of intellectual trick. Nevertheless, as Alvin Plantinga remarks, even though the argument may look unsound at first sight, “it is profoundly difficult to say what, exactly, is wrong with it.”[i] We’ll take a closer look at why this is the case when we consider common objections to the argument. But, for now, let’s just summarize the argument.
It is possible to conceive of the greatest being (“something than which nothing greater can be conceived”)
Whatever is conceivable exists in understanding.
Existing in reality is greater than existing in understanding.
Therefore, that than which nothing greater can be conceived exists in reality.
The first premise seems fairly easy to justify. The greatest conceivable being is a coherent concept, which means that it is logically possible. It is possible to conceive of something that is coherent. Anselm can plausibly be taken to mean that something that exists in understanding exists as a concept. But existing in reality is greater than existing as a concept. This would mean that the greatest conceivable being is not really the greatest conceivable being, because it exists only in understanding, which is a contradiction. Anselm puts it like this, “So if that than which a greater cannot be thought exists only in the understanding, then that than which a greater cannot be thought is that than which a greater can be thought. But that is clearly impossible.”[ii]To put it more simply, the statement “the greatest possible being is conceivable” contradicts the statement “the greatest possible being exists only as a concept.” If it is the greatest possible being is conceivable then it cannot exist only as a concept, because then there is a possible being that is greater than it ( i.e. one that also exists in reality). So it is not the greatest possible being if it is only a concept. But we’ve already seen that it is possible to conceptualize of the greatest possible being. So both cannot be true. Either it exists in reality or it is inconceivable. But it cannot be both conceivable and not exist in reality, otherwise there would be a possible being who is greater than the greatest possible being, which is a contradiction.
Greatest conceivable anything?
It is very common for critics of the argument to contend that the logic of the ontological argument can prove the existence of anything whatsoever, from greatest pizzas, to the worst conceivable being, or the greatest possible island. The problem with most of these objections is that islands or pizzas or other similar objects don’t have an “intrinsic maximum.”[iii] This means that the sorts of properties which would make an island great (such as the number of palm trees and amount of time in the sun) do not have a limit such that a greater number or amount of those properties would not always make it better. Or, “No matter how great an island is,…there could always be a greater…That is, there is no degree of productivity or number of palm trees (or of dancing girls) such that it is [logically] impossible that an island display more of that quality.”[iv]Apart from this, an island or pizza do not have objective great-making properties. How much cheese has to be on a pizza for it to be the greatest conceivable pizza? How many palm trees has to be on an island to make it the greatest conceivable island? These characteristics are subjective. It would be different depending on the person you ask and what their tastes are.
One might say it doesn’t matter that these objects have no intrinsic maximum. There are perhaps scientifically proven or objective measures that would make an island most enjoyable to people. But firstly, this would require the assumption that a great island is simply one that gives the greatest enjoyment to human beings. Why should that be the case? In addition, there will still be a large subjective component. Even if there is some baseline of enjoyment that can be scientifically proven, every person will have their own preferences that make the island most enjoyable to them personally. But then maybe the baseline represents the greatest conceivable island because that is exactly where subjectivity becomes necessary to make it greater. However, if the purpose of the island is for subjective enjoyment, it would not be the greatest conceivable island for most people, because most people would have individual preferences beyond the baseline (which would make them enjoy it more). So such an island would fail to provide the greatest enjoyment to human beings. What about a greatest conceivable human being? There may be some aspects of human beings that are objectively great-making. But how muscular should a human be, or how lean, for them to be the greatest conceivable human being? How physically attractive? Is someone who is physically attractive objectively superior to someone who is less physically attractive (or is this only an issue to potential romantic partners)? How tall? How long should he live? As long as possible or just as long so as to avoid the indignities and suffering of old age? What personality traits should he have? Pretty much the only characteristics of human beings that have an objective great-making quality is morality and belief. That person should believe all true things and do all right actions and no wrong actions. Firstly, these are not enough objective great-making properties, because something can conceivably have these properties (morality and true belief) and not be human. And secondly, there are too many other characteristics that are essential to being human (such as having a human body, having certain personality traits etc.) In short, any physical thing cannot have a greatest conceivable instantiation, because any physical thing does not have properties that have intrinsic maximums or are objectively great-making.
Existence is not a Predicate or Property
Immanuel Kant was a German philosopher who had a massive impact on the metaphysics and epistemology of early modern philosophy. His influence continues to this day. Kant’s philosophy led him reject the traditional arguments for God’s existence, such as the cosmological, teleological and ontological arguments, (although not the existence of God itself). Kant contended that the ontological argument invalidly supposes that existence is a kind of property that can be added to and subtracted from entities. Rather, existence seems to be presupposed for something to have properties. Let’s look at the objection in Kant’s own words:
“Being is evidently not a real predicate, that is, a conception of something which is added to the conception of some other thing. It is merely the positing of a thing, or of certain determinations in it. Logically, it is merely the copula of a judgment…Now , if I take the subject (God) with all its predicates (omnipotence being one)and say, God is, or, There is a God, I add no new predicate to the conception of God, I merely posit or affirm the existence of the subject with all its predicates –I posit the object in relation to my conception. The content of both is the same; and there is no addition made to the conception…”[v]
Many philosophers, including atheist philosophers like Peter Millican, do not believe that Kant’s objection is successful against Anselm’s ontological argument. This is because it is not clear how his ontological argument requires the assumption that existence is a property that is added to the conception of a thing. In order to show that Kant’s objection is successful, you need to show which premise of the argument implies that existence is a property. I suppose the best candidate would be the third premise (on my formulation): whatever exists in reality is greater than what exists in understanding. This premise simply contends that a being is greater when it exists than when it only has some sort of conceptual existence. Why does that imply that existence is a property? It isn’t clear. Perhaps you might say that the inference from the premises to the conclusion implies that existence is a property that is added to the concept of God. Any object whose existence is claimed can be conceived of as adding existence as a property to its concept. It would imply that any existential argument (any argument that implies that existence of something) implies that existence is a property, which is clearly false. Consider the following argument:
Some fossils, when reconstructed, show the shape of creatures called dinosaurs.
This fact is best explained by the idea that dinosaurs really existed long ago.
Therefore, dinosaurs existed.
You can read this argument as adding existence as a property to the concept of dinosaurs by inference from the premises, which would also make it invalid according to this construal of Kant’s objection.
But apart from this, it is not at all a given that existence is not a property at least in some sense. The fact that existence is presupposed in order for the being to have other properties doesn’t mean that the first property is not a property. For example, in order to have the property of being able to run fast one first needs to have legs (or good prostheses). Both the property required for another property and the other property are both properties. Secondly, whether or not existence is a property depends upon how you conceive of conceptual objects. It seems clear however, that when one is dealing with concepts or fictional characters (or, at any rate, things where existence is controversial) it certainly seems that existence is treated as a predicate or property. In addition, it seems false that, as Kant says, “no addition is made to the concept” by saying it exists. It seems clear however, that we think differently about things that we believe don’t exist (such as a unicorn) and things that we do believe exist (such as a mountain lion). Namely, we know that the one occurs in our world and the other does not. In short, the only way you can contend that existence is not a property is by defining it so that it is not a property (as Kant seems to do). But what makes Kant’s definition of existence as not being a property any better than someone else’s definition that it is a property?
Existence is not a Perfection
It seems to be a common sense claim that a being that exists is superior to the same being that merely exists as a conceptual object. I think it is clear that you would say it is better for you yourself to exist than not to exist. You wouldn’t normally hesitate to say that your own existence is better than your own non-existence. It would make you better if you existed than if you existed merely as a concept or a possible object. So why should we be hesitant to say it in the case of any other being, including the greatest conceivable being? Some philosophers respond to this objection by contending that even though existence may not be a perfection necessary existence is a perfection. The Hartshorne-Malcolm ontological argument makes use of this idea. It contends that a being that only exists in the actual world is inferior to a being that exists in every possible world including the actual world (a necessary being).
Worst Conceivable Being?
There is also a parody of the argument that follows the logic of the ontological argument but inserts the “worst” instead of “greatest.” Arguably, however, a being is even worse if it does not exist in reality, so it makes no sense to contend that the logic of the ontological argument applies to a worst conceivable being. Perhaps you might say that it would be worst if the being actually existed. But you must answer the question: for whom is it worst? We are not talking about whether the being would be the worst conceivable being for the world or for human beings, but the worst conceivable being in terms of its own properties. The worst conceivable being, in terms of its own properties, would not exist, because a being that doesn’t exist in reality is clearly inferior to one that does exist. Thus, the worst conceivable being cannot logically exist.
Defining God into Existence?
A common critique of the ontological argument is that it simply defines God into existence. It contends that existence or necessary existence is part of the definition of God and because of that, God exists. This may be true of Rene Descartes’s version of the ontological argument, which I think is the weakest version (and at which Immanuel Kant’s criticisms were originally aimed). However, if you look at Anselm and modern formulations of the ontological argument (such as by Plantinga, Hartshorne and Malcolm) it becomes impossible to maintain this critique. For example, the Anselmian ontological argument clearly doesn’t even define God. In fact, it doesn’t even deal with God. It’s conclusion is simply that the greatest conceivable being exists, and it is a further step to identify this with God. Anselm deals simply with what properties the greatest conceivable being will have and these can be determined objectively. It then looks at the logical implications of a greatest conceivable being (one of them being existence). None of these arguments contain any version of the following reasoning process “By definition, God is an existent being, therefore God exists.” The ontological argument is about what the implications are of a concept of a greatest conceivable being. If this is really what the ontological argument boils down to, then you should be able to use its logic to prove the existence of anything you want. As we’ve already seen ( through the response to the first objection) this is not even close to possible.
[i] Alvin Plantinga, “A Contemporary Modal Version of the Ontological Argument”, in Philosophy of Religion: Selected Readings ed. Michael Peterson, William Hasker, Bruce Reichenbach and David Basinger, 4th ed. (New York: Oxford University Press, 2010) 174
[ii] Saint Anselm, “The Classical Ontological Argument,” in Philosophy of Religion: Selected Readings ed. Michael Peterson, William Hasker, Bruce Reichenbach and David Basinger, 4th ed. (New York: Oxford University Press, 2010) 170
[iii] Alvin Plantinga, “A Contemporary Modal Version of the Ontological Argument” , 176
[iv] Ibid., 176
[v] Immanuel Kant, Critique of Pure Reason, trans. J.M.D Meiklejohn, (Mineola, New York: Dover Publications, 2003) 335