Philosophy of Religion

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Gaunilo of Marmoutiers’ objection to Anselm’s Argument

One problem with Anselm’s ontological argument for the existence of God is that it invites parody. Parallel arguments purporting to prove the existence of any perfect thing at all can be constructed. This objection was first raised by one of Anselm’s contemporaries, the monk Gaunilo of Marmoutiers, who constructed an ontological argument for the existence of the perfect island in his On Behalf of the Fool.
  1. Gaunilo invited his readers to think of the greatest, or most perfect, conceivable island.
  2. As a matter of fact, it is likely that no such island actually exists.
  3. 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.
  4. Since we can conceive of this greatest or most perfect conceivable island, then it must exist.
Gaunilo argued that this line of argument was no less absurd than Anselm’s orginal argument.

Similar arguments for the existence of the perfect baseball pitcher, or the perfect husband or dragons or even unicorns —for the existence of any perfect thing at all—can be constructed. If any of these arguments is sound, it seems, then they must all be sound.

Clearly, though, these arguments are not all sound; the perfect baseball pitcher does not exist, and neither does the perfect husband. There is something wrong with the logic of these arguments. Each of these ontological arguments, though, uses the same logic. They must therefore all be unsound.

The fact that there is no perfect island, and no perfect baseball pitcher, then, shows that the logic of the ontological argument for God’s existence is flawed.

Such objections are known as "Overload Objections"; they don't claim to show where or how the ontological argument goes wrong, they simply argue that if it is sound, then so are many other arguments of the same logical form which we don't want to accept, arguments which would overload the world with an indefinitely large number of things like perfect islands, perfect pizzas, perfect pencils, etc.

Such objections always depend upon the accuracy of the analogy. That is, we must be able to show that the objector's argument is sufficiently like the ontological argument for us to be able to conclude that if one works so must the other.

Criticisms of Gaunilo’s Objection – Anselm’s Reply

The main problem with Gaunilo’s objection is the definition of ‘perfect’. There will be disagreements as to what makes an island perfect i.e. tropical, deserted, inhabited…etc. When we analyse it any definition here of ‘perfect’ in the case of an island would be subjective. Your idea of a perfect island might not be my idea of a perfect island.

Another problem is the use of the term ‘perfect’ in the case of islands. By definition any piece of land surrounded by water is an island. Any piece of land perfectly (i.e. – completely) surrounded by water is a ‘perfect island’. In this case all islands are perfect islands.

Anselm would argue that this line of argument does not work for everyday objects. Anselm is concerned with a being and a necessary being at that – the greatest being one can conceive.

Anselm argued that he was not talking about temporal contingent things such as islands which are rooted in time and space. Such things are dependent upon other things for their existence. Anselm is talking about the greatest thing that can be thought. God is not contingent or temporal. God’s existence is necessary i.e. not dependent upon other things for his existence.


Necessary – inevitably resulting from or produced by the nature of things…etc., so that the contrary is impossible.

Contingent – that which need not be, that which could have been different; something that has dependency.

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