Descartes dedicates Meditation Three and Meditation Five to proving the existence of God. Contemporary readers might find his reasoning convoluted and his interest in God unusual, given that he emphasizes finding truth through pure rationality. Yet Descartes was a devout Catholic and, in his time, rejecting God’s existence was all but unthinkable. Indeed, Descartes’s work was actually considered radical because it doubted God’s existence at all, and because it argued that reason—not faith—should be the foundation for human knowledge.
In the Third Meditation, the Meditator presents a complex proof for God’s existence. He argues that the cause of any idea must have as much formal reality as the idea has objective reality. In very simplified terms, this effectively means that, if he can imagine something, there must be something real that is similar to the thing he imagined. Yet God is by definition infinite, so if He didn’t really exist, there would be nothing else like Him that could give us the idea that He did exist. Thus, God must exist, and He must have directly given us the idea of His existence.
The argument in the Fifth Meditation is more straightforward: the Meditator clearly and distinctly sees that “a supremely perfect being” would have every kind of perfect quality, one of which is that this being “always exists.” Again, according to the Meditator, the very idea of God inherently proves that God must exist. In both cases, the Meditator concludes that God is perfect, infinite, eternal, all-powerful, and all-knowing, and he uses God’s existence as the foundation for his conclusion that his clear and distinct perceptions are reliable. Yet this has proven highly controversial: Descartes’s critics have frequently pointed out that he uses clear and distinct perceptions to prove that God exists, but then he claims that these same perceptions are only reliable because God exists. Regardless, Descartes’s arguments are intended to offer not only clear proofs of God’s existence, but also undeniable evidence that rationalist philosophy is totally compatible with traditional religious faith.
God and the World ThemeTracker
God and the World Quotes in Meditations on First Philosophy
I am certain that I am a thinking thing. Do I not therefore also know what is required for my being certain about anything? In this first item of knowledge there is simply a clear and distinct perception of what I am asserting; this would not be enough to make me certain of the truth of the matter if it could ever turn out that something which I perceived with such clarity and distinctness was false. So I now seem to be able to lay it down as a general rule that whatever I perceive very clearly and distinctly is true.
When I say “Nature taught me to think this,” all I mean is that a spontaneous impulse leads me to believe it, not that its truth has been revealed to me by some natural light. There is a big difference here. Whatever is revealed to me by the natural light—for example that from the fact that I am doubting it follows that I exist, and so on—cannot in any way be open to doubt. This is because there cannot be another faculty both as trustworthy as the natural light and also capable of showing me that such things are not true. But as for my natural impulses, I have often judged in the past that they were pushing me in the wrong direction when it was a question of choosing the good, and I do not see why I should place any greater confidence in them in other matters.
Undoubtedly, the ideas which represent substances to me amount to something more and, so to speak, contain within themselves more objective reality than the ideas which merely represent modes or accidents. Again, the idea that gives me my understanding of a supreme God, eternal, infinite, immutable [sic], omniscient, omnipotent and the creator of all things that exist apart from him, certainly has in it more objective reality than the ideas that represent finite substances.
It is manifest by the natural light that there must be at least as much reality [sic] in the efficient and total cause as in the effect of that cause. For where, I ask, could the effect get its reality from, if not from the cause?
It is clear to me, by the natural light, that the ideas in me are like pictures, or [sic] images which can easily fall short of the perfection of the things from which they are taken, but which cannot contain anything greater or more perfect.
So there remains only the idea of God; and I must consider whether there is anything in the idea which could not have originated in myself. By the word “God” I understand a substance that is infinite, eternal, immutable [sic], independent, supremely intelligent, supremely powerful, and which created both myself and everything else (if anything else there be) that exists. All these attributes are such that, the more carefully I concentrate on them, the less possible it seems that they could have originated from me alone. So from what has been said it must be concluded that God necessarily exists.
It is true that I have the idea of substance in me in virtue of the fact that I am a substance; but this would not account for my having the idea of an infinite substance, when I am finite, unless this idea proceeded from some substance which really was infinite.
It is enough that I understand the infinite, and that I judge that all the attributes which I clearly perceive and know to imply some perfection—and perhaps countless others of which I am ignorant—are present in God either formally or eminently. This is enough to make the idea that I have of God the truest and most clear and distinct of all my ideas.
But before examining this point more carefully and investigating other truths which may be derived from it, I should like to pause here and spend some time in the contemplation of God; to reflect on his attributes, and to gaze with wonder and adoration on the beauty of this immense light, so far as the eye of my darkened intellect can bear it. For just as we believe through faith that the supreme happiness of the next life consists solely in the contemplation of the divine majesty, so experience tells us that this same contemplation, albeit much less perfect, enables us to know the greatest joy of which we are capable in this life.
I realize that I am […] something intermediate between God and nothingness, or between supreme being and non-being: my nature is such that in so far as I was created by the supreme being, there is nothing in me to enable me to go wrong or lead me astray; but in so far as I participate in nothingness or non-being, that is, in so far as I am not myself the supreme being and am lacking in countless respects, it is no wonder that I make mistakes. I understand, then, that error as such is not something real which depends on God, but merely a defect. Hence my going wrong does not require me to have a faculty specially bestowed on me by God; it simply happens as a result of the fact that the faculty of true judgement which I have from God is in my case not infinite.
So what then is the source of my mistakes? It must be simply this: the scope of the will is wider than that of the intellect; but instead of restricting it within the same limits, I extend its use to matters which I do not understand. Since the will is indifferent in such cases, it easily turns aside from what is true and good, and this is the source of my error and sin.
But if the mere fact that I can produce from my thought the idea of something entails that everything which I clearly and distinctly perceive to belong to that thing really does belong to it, is not this a possible basis for another argument to prove the existence of God? Certainly, the idea of God, or a supremely perfect being, is one which I find within me just as surely as the idea of any shape or number. And my understanding that it belongs to his nature that he always exists is no less clear and distinct than is the case when I prove of any shape or number that some property belongs to its nature.
For what is more self-evident than the fact that the supreme being exists, or that God, to whose essence alone existence belongs, exists?
Now, however, I have perceived that God exists, and at the same time I have understood that everything else depends on him, and that he is no deceiver; and I have drawn the conclusion that everything which I clearly and distinctly perceive is of necessity true. Accordingly, even if I am no longer attending to the arguments which led me to judge that this is true, as long as I remember that I clearly and distinctly perceived it, there are no counter-arguments which can be adduced to make me doubt it, but on the contrary I have true and certain knowledge of it. And I have knowledge not just of this matter, but of all matters which I remember ever having demonstrated, in geometry and so on.
Thus I see plainly that the certainty and truth of all knowledge depends uniquely on my awareness of the true God, to such an extent that I was incapable of perfect knowledge about anything else until I became aware of him. And now it is possible for me to achieve full and certain knowledge of countless matters, both concerning God himself and other things whose nature is intellectual, and also concerning the whole of that corporeal nature which is the subject-matter of pure mathematics.
My final observation is that any given movement occurring in the part of the brain that immediately affects the mind produces just one corresponding sensation; and hence the best system that could be devised is that it should produce the one sensation which, of all possible sensations, is most especially and most frequently conducive to the preservation of the healthy man. And experience shows that the sensations which nature has given us are all of this kind; and so there is absolutely nothing to be found in them that does not bear witness to the power and goodness of God.