Descartes & the Ontological Argument

I am going to continue discussion of the ontological argument for god’s existence and Anselem’s proof that I started with my last post. The argument is picked up by Descartes who uses it in his Meditations on First Philosophy. Desartes needs to prove God’s existence in order to demonstrate that an external world exists (and thereby opening up the possibility for doing science) and to undermine skepticism in general. Just as Kant will later do with his “Refutation of Idealism” as I mentioned in a previous post, Descartes is trying to prove that there is and external world that we know and there is no way of doubting it. This requires him to undermine the skeptical rejoinder that we could be deceived about the external world by an all-powerful deceiver. The precise logic of this can be a bit murky and Descartes isn’t usually very explicit with his reasoning, but the important idea is that reason leads me to think that external bodies exist and a benevolent God ensures that reason, when used correctly, will lead to truth.

Descartes uses more than one argument to prove God’s existence. The other significant argument, which appears in the Third Meditation, is basically: 1) I have an idea of an infinite all-perfect God; 2) I, as a finite imperfect thing, could not create this idea, it could have only be created by a perfect being like God; 3) therefore it must come from God. This idea of God is “the mark of the craftsmen stamped on his work”: in other words, God created me, and he has signed his work by placing in me the idea of God. Obviously, the second step is the one that is probably the least convincing. Descartes tries to strengthen it by distinguishing “actually infinite” (God) from “potentially infinite” (like the number infinity, or an infinitely divisible line) ideas. Thus, he is able to dodge the refutation that our mind can create infinite ideas, by saying our mind can only create potentially infinite ideas and not actually infinite ideas. My objection at this is: if the mind can contain an actually infinite idea, shouldn’t it be able to create it? and if the mind can’t entirely contain it, how can the mind know it’s actually infinite? But the whole argument has such dubious and speculative assumptions that ultimately one should just dismiss it as resting on baseless assertions.

Descartes also uses a version of Anselem’s argument to prove God’s existence. Why two arguments? I think they complement and strengthen each other. The first is an epistemological argument (epistemology=the study of how we know) the second is an ontological argument (ontology=the study of existence). This argument rests on the inseparability of the idea of God from existence. In other words, I cannot but think of God clearly and distinctly without thinking of God’s existence. Descartes had earlier proved that the quality of an idea being clear and distinct makes that idea true. Thus, if God and existence are inseparable then God must exist. Introducing this idea of “clear and distinct” avoids the objection that I raised in my last post to Anselem’s argument, that our mind can essentially will a perfect thing into existence by just having an idea of it, since Descartes is instead saying that we can’t perceive anything untrue clearly and distinctly. Descartes also introduces another notion, of the inseparability of perfection to dodge Guanilo’s perfect island counter-example. In other words, Descartes says that no thing can have only one perfect quality; it must be perfect in every way or perfect in no way at al. An island, by being a material thing is necessarily imperfect; therefore a perfect island is nonsensical.

Ultimately, Descartes arguments are an improvement on Anselem's, but the assumptions they rest upon are of such a dubious nature that it’s hard to find them convincing. The second proof of God’s existence dependence on the notion that clear and distinct perceptions indicate truth. Descartes earlier demonstrates this, but his proof rests on his assumption that God exists, which thus means it depends on his first proof of God’s existence, which itself dependence on the shaky empirical observation that we all have an inherent idea of an actually infinite and all-perfect God and that we couldn’t possibly create such an idea on our own. It’s a good example of a vertical argument, with arguments depending on previous arguments and assumptions, such that the whole thing easily collapses once we bring doubt to earlier premises.

Nonetheless, it’s not the last we’ll see of Anselem and the Ontological proof, as I want to explore critical responses to it from the likes of Kant, Russel and Hume.