The Ontological Argument was first so-called by Immanuel Kant, who sought to destroy the attempt to establish God’s existence a priori that had been made by Leibniz, Descartes and first by St Anselm.  In basic terms the Ontological Argument suggests that since

• P1. God is supremely perfect

and

• P2. Existence in reality is better than existence only in the mind
• C.   God therefore must exist.

The argument contends that real existence is a necessary part of the concept of God and thus that attempts to deny God’s existence are foolish.  Anselm quoted Psalm 14:1 and concluded that atheists assert a straightforward contradiction, in effect saying “God (who by definition must exist) does not exist”.   While the argument seems like “a charming joke” (as Schopenhauer put it), as even the Bertrand Russell remarked, it is much more difficult to show how it fails.  Nevertheless, the Ontological Argument does fail for the reasons set out by Kant in his Critique of Pure Reason.

Kant aimed his critique at Descartes’ version of the Ontological Argument, although his points do relate to other versions as well.  Descartes developed his argument in several places, but the most well known version is in his Fifth Meditation, where he reflected that the existence of a supremely-perfect being was as undeniable and necessary as three sides are to a triangle or valleys are to hills.  Like Anselm, Descartes suggests that existence is part of the definition of God as supremely perfect (as Anselm put it “that than which nothing greater can be conceived of”).  Kant rejected this absolutely.  For Kant all knowledge claims are either synthetic or analytic.  Synthetic claims refer to experience and so add to our knowledge of the world, but they always contain the possibility of being true or false.  Analytic claims are based on logic, reason. The relationships between concepts – if valid they provide certainty, proof, but they are tautologous and do not add to our stock of knowledge, they just clarify our understanding and so provide insight.  Kant argued that the Ontological Argument analyses the concept of God and claims to find existence within it. Although it is analytic, it makes an existential claim.  Kant argues that this is impossible – all existential claims must be synthetic – and this is highly persuasive.  Analytic statements cannot expand our knowledge of what does or does not exist in the real world. As Gaunilo remarked in response to Anselm in his essay “on behalf of the fool,” it is absurd to try to define something into existence.  If somebody suggested that a perfect island exists just because by definition it has to, nobody would book tickets to go there on holiday!  Kant’s division of knowledge into synthetic and analytic is still widely accepted, as is his argument that all existential claims must be synthetic, despite WV Quine’s criticism of Kant’s understanding of knowledge.  Quine claimed that the division of all knowledge into synthetic and analytic was a “dogma of empiricism” and only true within Kant’s own limited worldview.

Kant went on to show how the Ontological Argument makes the assumption that existence is a perfection.  Both Anselm and Descartes argue that it is better, more perfect, to exist in reality (in re) than just in the mind (in intellectu) but, as Kant points out, there is no difference between the concept of a real $100 and an imaginary $100 – the concept remains the same whether the money is in my pocket or in my head.  Existence does not add a single penny to the concept, it just tells me where (and if) the concept has been actualised. Related to this is Kant’s famous observation that existence is not a predicate and that the Ontological Argument rests on poor grammar.  A predicate is a word that describes an object.  Although superficially it seems that existence adds to our knowledge of an object, in practice it is the basis on which any claims to knowledge about an object make sense.  Take a job interview.  If there are two candidates, equally well qualified, but it later emerges that only one exists it is not a case of saying that the real candidate is better than the fictitious one but it is a case of saying that the contest was a joke.  As Bertrand Russell remarked, if I ask you “has the present King of France got blonde hair and blue eyes” I smuggle the assumption that there IS a present King of France into my question.  Actually, there is no present King of France so my question is meaningless and can’t be answered either correctly or incorrectly.  This is a difficult point to deny and seems to conclusively destroy the Ontological Argument’s claim to proving God’s existence.  Although there is an intuitive human appeal to the idea that a (any?) real chocolate cake, island – or God – is better than one that only exists in the mind, in practice that cannot be sufficient basis for a claim that God exists.

Kant’s criticisms of the Ontological Argument show that it fails in its object of proving God’s existence. Of course that does not mean that God does not exist.  Just because the Ontological – or any – argument for the existence of God is found to be unsound has no effect on the existence or non-existence of God, although it does take away one support for Propositional faith.  Is it fair to say that as a failed argument the Ontological Argument really is a “charming joke” then?  Absolutely not.  Anselm originally titled the Proslogion “Fides quaerens intellectum”; in the process of faith seeking understanding the Ontological Argument succeeds in clarifying our understanding of the nature and limits of human knowledge.  As such, the argument continues to have great significance.  Further, as both Karl Barth and Iris Murdoch suggested, the argument invites believers to reconsider what they mean by existence, particularly when it comes to God.  Do believers really expect God to be real in the way that a perfect island might be real, or do they have a different sort of reality in mind?