Lecture Supplement on Descartes

87 Descartes says that “...nothing seems more pressing than that...I see whether anything certain is to be had concerning material things.” But before going on to deal with our knowledge of material things (the central topic of the Sixth Meditation), he discusses our knowledge of mathematics and of his deity (again). This discussion is important because it provides him with a first and general opportunity for indicating how one proceeds from clear and distinct ideas to the world, and because it indicates something about the world itself independent of our thoughts about it.^{^[2]}

88 “...I find within me countless ideas of certain things, that, even if they do not exist anywhere outside me, still cannot be said to be nothing. And although, in a sense, I think them at will, nevertheless they are not something I have fabricated; rather they have their own true and immutable natures. For example, when I imagine a triangle even if perhaps no such figure exists outside my thought anywhere in the world and never has, the triangle still has a certain determinate nature, essence, or form which is unchangeable and eternal, which I did not fabricate, and which does not depend on my mind.”

-What does this paragraph say? Draw a triangle on the board. Is it a triangle?^{^[3]} Where are triangles? Are they real?

-88 Some mathematical truths are listed and he says that “all these properties are patently true because I know them clearly, and thus they are something and not merely nothing. For it is obvious that

[1] whatever is true is something [truths are about “something”—there can be no truths about my former student who is President of the United States as none of my former students have reached this office],

[3] it follows that all that I clearly and distinctly perceive to belong to that thing really does belong to it,

therefore (from 1, 2, 3, and 4), mathematical things are [that is, they exist].

At this point, it appears, there is a gigantic switch of topic, both in this Meditation, and in the Meditations in general. We move to an ontological proof for the existence of a deity. Is this such a major shift however? The certainty Descartes arrives at in his earlier Meditations, as he himself admits, depends upon the nonexistence of an evil genius and upon the existence of a deity. His proofs hang in limbo as long as they begin with that which is dependent and endeavor to move forward. He must “begin” [ontologically speaking] with that which is wholly independent, and show (with certainty) that this starting point is secure. The goal of the following proof is to provide him with an “ultimately secure” beginning point—to provide Descartes with the metaphysical ground upon which his epistemological conclusions may stand.

Throughout the Meditations, Descartes has been concerned with metaphysics. He has asserted that he is a substance; drawn a distinction between mental and physical substances (and between finite and infinite ones); discussed the status of attributes; offered a causal principle; discussed the objective reality (representational capacity of ideas); pointed out that true ideas must represent something real; and, now, discussed the status of mathematical truths. Clearly, he is vitally concerned with metaphysics, but he has not discussed the topic directly on its own. He has been discussing and developing his topics according to an “epistemological order” (following what commentators call “the order of ideas”); and he now pauses to discuss to discuss things according to a “metaphysical order” (what commentators call “the order of things [or being]”). This means, given his orientation, that he must start with the foundation of everything which exists, and this is, of course, his deity. Thus we have a second, and very different, argument for the existence of his deity—one which doesn’t begin from the self and work outward to the deity. Instead, it begins with the deity itself and shows that it, by its very nature, must [necessarily] exist.

2. He has been accustomed in every other matter to distinguish between existence and essence; and so he believes that the existence can be separated from the essence of his deity, and that, thus, his deity may be conceived as not actually existing.

3. But this case is different: “...the existence can no more be separated from the essence of God, than the idea of a mountain from that of a valley, or the equality of its three angles to two right angles, from the essence of a triangle; so that it is not less impossible to conceive a God, that is, a being supremely perfect, to whom existence is awanting, or who is devoid of certain perfection, than to conceive a mountain without a valley.”

4. Therefore, his deity exists necessarily. Note that there is a difference between concluding that “it is necessary to conclude that God exists” [Meditation III] and concluding that “necessarily, God exists.” (See long citation on pp. 90-91).

-“Next, I cannot understand how there could be two or more Gods of this kind. Again, once I have asserted that God now exists, I plainly see that it is necessary that he has existed from eternity and will endure for eternity.”^{^[4]}

--Why is it necessary that his deity be unique—that there be only one of such things? Couldn’t “what’s real is rational, and what’s rational is real” be true if there are several such beings? The need for it to be a universe!

--Why is it necessary that his deity is “eternal?” Because if it were not, it would be caused, and it would have an end, and neither of these occurrences would be compatible with necessary existence.

90-91 “...the things that fully convince me are those that I clearly and distinctly perceive. And although some of these things I thus perceive are obvious to everyone, while others are discovered only by those who look more closely and inquire carefully, nevertheless, once they have been discovered, they are considered no less certain than the others. For example, in the case of a right triangle, although it is not so readily apparent that the square of the hypotenuse is equal to the sum of the square of the other two sides as it is that the hypotenuse is opposite the largest angle, nevertheless, once the former has been ascertained, it is no less believed. However, as far as God is concerned, if I were not overwhelmed by prejudices and if the images of sensible things were not besieging my thought from all directions, I would certainly acknowledge nothing sooner or more easily than him. For what, in and of itself, is more manifest than that a supreme being exists, that is, that God, to whose essence alone existence belongs, exists?”

-91 “...I now am just as certain about this as I am about everything else that seems most certain. Moreover, I observe also that certitude about other things is so dependent on this, that without it nothing can ever be perfectly known.”^{^[5]}

91-92 His deity guarantees that past clear and distinct ideas may be relied upon: “...even if I no longer attend to the reasons leading me to judge this to be true, so long as I merely recall that I did clearly and distinctly observe it, no counter-argument can be brought forward that might force me to doubt it. On the contrary, I have a true and certain knowledge of it.”

-“...even if I were dreaming, if anything is evident to my intellect, then it is entirely true.

And thus I see plainly that the certainty and truth of every science depends exclusively upon the knowledge of the true God, to the extent that, prior to my becoming aware of him, I was incapable of achieving perfect knowledge about anything else. But now it is possible for me to achieve full and certain knowledge about countless things....”

So, at the end of this Meditation we each have knowledge of ourself, a deity, mathematics, and the “guarantee” that clear and distinct ideas serve as a valid criterion of truth. For Descartes this deity serves as the validator, and clarity and distinctness serves as the criterion of knowledge (about self, deity, and world)—of course, the deity “validates” the criterion.

William Alston offers an excellent critical treatment of Descartes’ version of the ontological argument in his “The Ontological Argument Revisited.”^{^[6]}

Notes: [click on note number to return to the text for the note]

[1] This supplement, and the others for Descartes’ Meditations on First Philosophy, reference the pages in Donald A. Cress’ translation in René Descartes: Discourse on Method and Meditations on First Philosophy, Fourth Edition (Indianapolis: Hackett, 1998). This supplement, and the others for Descartes’ Meditations on First Philosophy, reference the pages in Donald A. Cress’ translation in René Descartes: Discourse on Method and Meditations on First Philosophy, Fourth Edition (Indianapolis: Hackett, 1998). They were developed over 40 years of teaching, however, and the citations are sometimes to other translations. In addition emphasis (italics, underlines, and bolding are regularly added to citations to help direct your attention.

[2] For another class I have a lecture supplement on Anselm’s ontological argument, and students may find this helpful in both understanding Descartes’ argument, and in contrasting Anselm’s medieval orientation with Descartes’ modern one. One can find many translations of Anselm's argument online, but I recommend looking at Chapters I-IV of Fordham University's Sourcebook on Anselm.

[3] Note the difference between a picture, or representation of a triangle, and a triangle!

[4] Note that from the fact that “he can not understand how there could not be two” deities of the identified type, it clearly does not follow that there is only one (let alone follow with any sort of necessity). Were he to say that he clearly and distinctly “perceives” (conceives) that there is only one, then, at least within his world-view, this might follow, but he doesn’t make even that claim here.

[5] Note the relevance of this passage to the issue of circularity which arose in Meditation Three.

[6] William Alston, “The Ontological Argument Revisited,” in Descartes: A Collection of Critical Essays, ed. Willis Doney (Garden City: Anchor, 1967), pp. 278-302. The essay originally appeared in The Philosophical Review v. 69 (1960), pp. 452-474.