Kant criticized Anselm's argument for the existence of God by counter arguing the expression 'God exists' adds nothing to our meaning of God and so it cannot be true a God that exists is greater than a god that does not exist.

Yet, modern atheists, most frequently say such things as unicorns, dragons, fairies, ghosts, the great pumpkin, etc. do not exist. So it seems existence is a predicate according to them.

Why is existence not a true predicate with respect to Anselm's argument? What is the main difficulty with his argument besides Kant's criticism?

4 Answers 4


The problem with Anslem's argument is not existence being a true predicate for God as a concept. 'God' when conceived of as a concept exists but only in our mind. However Anslem failed to see that concept of an infinite God is not infinite itself. So from an existing concept of God it never follows that there must be an actual existing God in reality, just as it doesn't follow from mental existence of a unicorn that it exists in the external world! It is as simple as that!

  • The intellect is the most obscure part of a human being; it occupies no space and cannot be touched (i.e. not the same thing as the brain); are you sure things in the mind cannot be infinite (unbounded, limitless)? Commented Oct 6, 2014 at 9:31
  • @MichaelLee, I agree with the distinction between mind and brain. With some correction, it is also true that human intellect is potentially infinite, i.e. has the ability to conceive infinite number of concepts and images. But here we are talking about whether or not a single concept can be infinite which is an impossibility. Because if any single mental entity was infinite, there could exist no other entity at all because that would occupy all the intellect. All mental entities are essentially bounded due to their very nature of being distinct from others.
    – infatuated
    Commented Oct 6, 2014 at 11:01
  • You are right they must be distinct from each other. Your mind, mine and everyone elses' are completely private from each other and I like it that way. But it brings into question the very existence of thought because if the universe consists of only 'atoms and void', all I can envision is a massive "blob" of atoms flying around each other. Why is it the atoms that make up people possess the capacity to think as opposed to those things, such as a rock, lack this ability? You're going to find this funny, I argued this to my metaphysics professor in a paper and he gave me an "F" Commented Oct 7, 2014 at 7:37
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    In the middle of this hierarchy or gradient of existence lie the Platonic perfect Forms for which the material/natural phenomena is only an imperfect, divisive reflection or shade. Now once the material phenomena (as whatever way perceived, visually, audibly etc) gets to more genuinely reflect the qualities of the perfect Forms or inherent workings of existence (such as the recurring nature of creative emanation of the One) they sound more and more beautiful to us. This is in a very rough nutshell what I believe about nature of beauty. Btw, this could have made a good topic for a separate Q&A!
    – infatuated
    Commented Oct 12, 2014 at 4:58
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    @infatuated - Nice idea about music. Have you checked out Heinrich Schenker? I think he'd be on your wavelength. I'd agree about hierarchies and suspect that a natural understanding of these gives musicians an edge in metaphysics.
    – user20253
    Commented Jan 11, 2018 at 14:14

The problem is not that existence is a predicate. Clearly it is.

The problem is that Anselm says existence is a perfection; so that a unicorn that exists is "more perfect" than one that does not exist.

That's where the argument gets into trouble. If you defined a "perfect unicorn" as a unicorn that has all perfections available to unicorns; then clearly a perfect unicorn must exist; because if a perfect unicorn does not exist, then it lacks a perfection, that of existence, contradicting its definition.

Existence is a predicate. But it is not a "perfection." And what is a perfection, exactly? It seems to be no more than an artificial device introduced so that Anselm's reductio can go through.

You could argue, as Plato does, that existence is an imperfection. The rock in my hand is but an imperfect, earthly representation of the ideal of rockness. The ideal unicorn is far better than a real unicorn, which eats too much and makes a mess in its stall.

So the flaw in Anselm's argument is the premise that "Existence is a perfection." Where is the evidence for that statement?

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    It is not at all clear if existence is a predicate ... See Existence Commented Sep 27, 2014 at 11:14

Short story:Imagine a unicorn and list all its properties: What does it look like, how does it smell... The (shortened) result will be something like "Like a white horse with a horn". Now add to that list "it exists", and look at it again. It will look like a white horse with a horn. Nothing has changed. It does not add to the concept in any way.

The reason is, that when you think of an unicorn you already thinking of it as existing. Only existing things can be white or have a horn. It makes no difference if you think of an unicorn and say "This is a unicorn" or see a unicorn and say "This is a unicorn". The additional existence of the second unicorn does not make it wrong to say of a unicorn that "lacks" that existence that it is a unicorn too. They have no different sets of properties and hence "existence" cant be such a property. So a unicorn isn't getting any more perfect when it is real. It is as perfect as the imagined one.

  • There is a longer story, but I never read Kant in English and I noticed, that it takes me considerable amount of time to find the correct translations for his terminology. So maybe someone else can tell the longer story.
    – Einer
    Commented Sep 26, 2014 at 19:27
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    "Only existing things can be white or have a horn." -- I disagree. Ahab is the captain of the Pequod, is he not? Ahab does in fact have properties, even though he's fictional.
    – user4894
    Commented Sep 26, 2014 at 19:40
  • @user4894 But when you think of him you think of him as existing. Did a fictional whale bite off his leg? No, fictional things can't bite you. Ahab would agree! Joking aside: Ahab had no different set of properties if he were real. Otherwise he weren't captain Ahab, because he differs from him in being real (if being real was a property).
    – Einer
    Commented Sep 26, 2014 at 19:45

I'm no expert but I think the way in which Kant's comments apply to Anselm's argument are to undermine the idea that the concept of something and the corresponding being are different. He says that nothing is added to the concept to get the real thing. Something like 'there is no more in a hundred conceptual dollars than there is in a hundred real dollars', for if there were, then the concept would not accurately represent the real thing....I personally see a problem with this, as I think concepts are worlds apart from real objects.

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