Descartes’ Ontological Argument: A Critique

During the seventeenth century the French rationalist René Descartes constructed a series of sixth short essays known as ‘The Meditations’, in which Descartes proposed to demolish all his beliefs in order to make way for certain truth upon which he could build all further knowledge upon. Descartes points out in ‘The Meditations’ that the only certain truth must be of the metaphysical, thus this must be the root for all knowledge. Since certain truth, for Descartes at least, comes from metaphysics then it knowledge must have a metaphysical cause, hence Descartes spends some time throughout ‘The Meditations’ trying to prove that it is necessary for God to exist since God is the only metaphysical entity we can rely on to be non-deceiving and therefore use as the root system for the tree of knowledge. Descartes uses a set of three arguments to prove God’s existence; however these arguments turn out to be partly unsuccessful as we can only prove that God exists as an idea.

Descartes’ first causal argument claims we can prove God exists because any idea we hold must be true as we cannot prove false that we have the idea of it and no idea can be any less true than another since they are all ideas of equal existence within our minds. However since we hold minds of a finite capacity then we can only conjure up ideas of finite things, such as hippogriffs or phoenixes, anything greater than our finite capacity must have been placed within our minds by a greater entity. Since God is of infinite nature then it would be impossible for us to devise such an idea by ourselves and so the idea of God must come from another entity, also the idea must come from something of equal capability to the object in question, so God being infinite must have been the idea of an infinite mind and since God is the only infinite source we can hold the idea of the only answer we can rationally deduce is that God created himself, thus it is necessary that God exists in order for us to hold the idea of him.

The second casual argument begins by Descartes asking how he came into existence of which he poses three ways; himself, his parents or some first principle. He dismisses himself from the equation by stating that if he created himself he must hold an infinite power to do so since only an infinite power can create itself due to its nature of being infinite but during the first argument he had already claimed his was of finite nature. He then moves on to refute the claim that it must be his parents which caused his existence, since they would need to have been created by their parents who were in turn created by their parents and so in creating a state of infinite regress unless some first principle proves to be the ultimate cause. This proves, in Descartes eyes, that he must have been created by some first principle, which he names as God, and since he was created by this first principle it is necessary that it exists as something that does not exist could not create something that does, thus God exists through necessity.

In the fifth meditation Descartes puts forward a third and final argument, known as his ontological argument, which goes as follows: whenever Descartes imagines the idea of God he always imagines God as having a “supremely perfect being”[1], thus by this definition God must hold all attributes that entail perfection, including omnipotence, unconditional honesty, benevolence and also existence. Since God is ultimately perfect then God must exist since by definition God is perfect and by perfect we mean existing. Descartes then completes his argument by using a set a set of analogies to prove that the nature of a substance cannot be separated from the substance, therefore both nature and substance are mutually dependent. One of the analogies is of a geometric nature as Descartes takes the idea of a triangle, by nature a triangle has three angles and “that its three angles are equal to two right angles”[2]. The second analogy made is between a mountain and a valley, both are mutually dependant since there cannot be a mountain without a valley. From this line of argument Descartes concludes that God exists because he relies on his existence on order to maintain his perfection, just as the existence relies on God being perfect otherwise existence would not be necessary.

Sorell in page sixty-eight of ‘Descartes a Very Short Introduction’ states the arguments employed by Descartes in proving God’s existence are nothing more than circular argument, a form of sham-reasoning, since Descartes claims that he can only prove God’s existence by using clear and distinct premises, but Descartes also claims that he can only come across clear and distinct premises after he has proven God’s existence. This being the case then there are only two possible outcomes. One being that there are no clear and distinct premises so we shall never be able to prove God exists, because the only premises that we cannot hold any degree of doubt about are those of clear and distinct nature. Hence we can only ever doubt that God exists, to be certain either way it impossible. The other possibility is that there are clear and distinct premises and so we can prove that God exists but the certainty of the used premises do not rely on God’s existence, consequently God’s existence is not necessary for our capability of holding certain truth about anything, this refutes Descartes claim that God is the foundation needed for his metaphysics which is to be the root system to his metaphoric ‘tree of knowledge’. French scientist Pierre Petit also pointed out that it is difficult to accept Descartes claim that all humans hold an idea of God and God was necessary for certainty about all other knowledge, since even “the most dedicated atheists”[3] could hold with absolute certainty the Earth and Sun existed without needing God to exist. Following Sorell’s and Petit’s claims we can rationally conclude that either God doesn’t exist, or if he does we cannot be certain and it is also unnecessary that he exists.

Further criticisms of Descartes’ arguments come from Jorge Secada. Secada says the first casual argument “assumes knowledge of God’s essence before it [the argument] can draw its inference. As with the ontological argument, it too follows the essentialist path.”[4] By this Secada means Descartes is guilty of assigning the attribute of existence to God before actually proving that God exists in order to hold said attribute. This is a dangerous position to put oneself in since if it turns out that God doesn’t exist then he has misplaced the attribute since only existents, or substances as Descartes calls them, are capable of holding attributes, consequently if God does not exist then Descartes reasoning would fall down allowing refutation for the remainder of Descartes arguments. Secada also raises a concern with Descartes claim that only infinite entities could create themselves out of nothing and all infinite entities are perfect, but Descartes acknowledges his imperfection therefore he cannot be infinite. What Secada puts forward is the possibility that Descartes was infinite only decided to relinquish some of his perfections in order to create himself as a finite entity, having done this it was seem logical that Descartes would forget about his previous infinite self due to the newly acquired finite memory he had given himself. Even though this does propose that God is unnecessary it does raise the question why choose to be something less perfect? A plausible answer is we would do so because we had a reason for doing, only this reason remains unknown to us so it cannot be the case and therefore we can go someway to refute Secada on this occasion and accept Descartes’ proposal that we are incapable of creating ourselves, and thus some first principle must be our creator.

There is another concern we can make with Descartes arguments based on the claim that God is a “supremely perfect being”[5], if God is, as he is claimed to be, perfect then he would hold the attribute of being unconditionally benevolent, however this is not the case since we can see injustice happening in the world all the time, in fact the contemporary poet Churchill speaks about one particular type of injustice in his poem ‘Home’ which is to do with bullying. We can see this in the lines “watching outside nervously. Will they? Won’t they? Crash! Another window gone.”[6] An unconditionally benevolent God would not allow such a social injustice to occur and therefore God cannot be unconditionally benevolent. The point of this being that if it is possible that God is not unconditionally benevolent then it is also possible that God fails to hold other attributes that are necessary for perfection since God would have been proved to be imperfect. One attribute Descartes assigns to his concept of a perfect God is existence, but since God might possibly be imperfect then it is plausible to claim that it is possible that God fails to hold the attribute of existence in which case we can conclude that God does not exist. Although this conclusion is shaky as it is founded upon hypothetical reasoning, which has not been proven to be either true or false, thus we cannot use it as sound evidence against Descartes but merely as inductively forceful or unsound evidence.

However there is some support for Descartes assertions from the cosmological argument for the existence of God as put forward by Saint Thomas Aquinas in his Five Ways. Aquinas’ First Way states that “there must be a first cause of all change, since nothing changes itself”[7] and that we cannot have a series of causes leading to an infinite regress. This supports Descartes second causal argument as far as it proves that Descartes must have been caused by a first principle and not his parents, as the latter suggestion leads to infinite regress which is an illogical position. However what this first principle is remains unnamed, Aquinas only argues that it is what we call God he does not claim that it is God. Hence the first principle does not have to be God but some other infinite entity, perhaps even Anaximander’s apeiron. In fact if we look back upon what has preceded this section of the argument then we know that the first principle exists but it is nowhere mentioned that it must be perfect, only that God is perfect and it may be the case that God is not the first principle, in which case the apeiron might be the first principle since as it does not need to hold benevolence as a attribute allowing room for injustices to occur. Therefore, following Aquinas we can say that a first principle exists and that it is often called God but the existence of any such God is still questionable as the first principle may actually be something other than God.

To conclude it seems unlikely that God exists since we are capable of doubting God’s existence based on the injustice argument mentioned above and the dubious reasoning Descartes uses as highlighted by Sorell, not only this but following Sorell and Petit we can also see that God is unnecessary and since Descartes and Aquinas both claim that all existents require a necessary reason for existing then we have no reason for God to exist. On the other hand we should not completely dismiss Descartes arguments since there is certainty about the necessity for a first principle, and as Aquinas points out this is often called God, so what Descartes refers to as God in ‘The Meditations’ is not God as such but just a name for the first principle. Thus as long as God is used as a name for the first principle and we do not assume God is an actual entity then we say that God exists as an idea within our minds and any external God is unnecessary and cannot exist.


  • Burns. E & Law. S, ‘Philosophy for AS and A2’, Routledge, 2004
  • Descartes. R, ‘Discourse on Method and The Meditations’, Penguin Classics, 1968
  • Gaarder. J, ‘Sophie’s World’, Phoenix House, 1995
  • Secada. J, ‘Cartesian Metaphysics’, Cambridge University Press, 2000
  • Skirry. J, ‘Descartes a Guide for the Perplexed’, Continuum, 2008
  • Sorell. T, ‘Descartes a Very Short Introduction’, Oxford University Press, 2000
  • Wise. P et al, ‘POP! The Power of Poetry’, Young Writers, 2006

[1] Pg. 123, Burns. E & Law. S, ‘Philosophy for AS and A2’, Routledge, 2004

[2] Pg. 143, Descartes. R, ‘Discourse on Method and The Meditations’, Penguin Classics, 1968

[3] Pg. 52, Sorell. T, ‘Descartes a Very Short Introduction’, Oxford University Press, 2000

[4] Pg. 150, Secada. J, ‘Cartesian Metaphysics’, Cambridge University Press, 2000

[5] Pg. 123, Burns. E & Law. S, ‘Philosophy for AS and A2’, Routledge, 2004

[6] Pg. 477, Wise. P et al, ‘POP! The Power of Poetry’, Young Writers, 2006,

[7] Pg, 109, Burns. E & Law. S, ‘Philosophy for AS and A2’, Routledge, 2004

Posted on January 1, 2011, in metaphysical, philosophical and tagged , , , . Bookmark the permalink. 2 Comments.

  1. I think that before the existense of god’s prove, the ideas already are clair and distinct; god gives to them i)the correspondence between them and things outside mind and ii) correspondence between then and the essence of things outside. But both the scenario before the prove and after the prove do not make any change to the clarity and distinctness of the ideas it-self. Be clair and distinct, to correspond to something outside mind, and to correspond to the essence of something outside are three thing differents. For a idea be clair and distinct it is only necessary that it has no room any minimal doubt. So, the clarity and distinctness of the idea has no direct dependency on god.

  1. Pingback: The Ontological Philosophy of a Perfect God | The BitterSweet End

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