Meditations on First Philosophy (with Objections and Replies) | Study Guide

René Descartes

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Meditations on First Philosophy (with Objections and Replies) | Third Meditation: Of God: That He Exists | Summary



So far the Meditator has achieved the following certainty: he exists as a thinking thing. He also knows what he is thinking insofar as he thinks it, or reflects on it. At the present, however, he has access only to the contents of his mind but seeks knowledge of an external, or mind-independent, world, which may or may not exist.

The Meditator is also aware his judgments may be erroneous. He previously set aside the question of God's existence, knowledge of which is required for all other knowledge, apart from the certainty of the "I think." Before moving from this certainty to claiming knowledge of material things, the Meditator must resolve the question of God's existence.

The Meditator begins by analyzing the features of the certainty that he exists as a thinking thing. These are the clarity and distinctness of his perception. These guarantee the truth of the idea so perceived. Clarity and distinctness together form "a general rule" by which to determine the truth of an idea. When applied to ideas previously thought to be "certain and obvious"—that is, ideas derived from the senses—the Meditator realizes he was in error about the clarity of his perception. More specifically, he lacked clarity about the conformity of the idea to the object it presumably resembled.

Even otherwise clear ideas—such as those found in mathematics—are subject to the doubt of a deceiver. Here is where God is brought back into the argument. For it may be that God has either constructed the Meditator in such a way as to be deceived by even the most obviously true ideas or God actively deceives him. Not only does the Meditator not know if God is deceitful, he also doesn't know God exists. In order to remove this doubt, which prevents certainty of anything else, the Meditator "must examine whether there is a God, and, if there is, whether he can be a deceiver."

An examination of the Meditator's ideas reveals them to be one of three types: innate (inherent in the mind); adventitious (arising from an external source); and fictitious (self-produced; constructed or assembled from other ideas). The crucial worry over adventitious ideas is correspondence: "What reason do I have for thinking the ideas are like the things [they presumably resemble]?" On the one hand the Meditator understands their nature is such as to be independent of his will. In other words he does not bid them to appear, they simply do. Consequently, they must come from somewhere else.

The Meditator considers the possibility that there is some unknown faculty of his mind producing these ideas. To settle the issue, he moves on to consider ideas in terms of their "formal" (real) or "objective" (object of thought) reality. One idea, God, "certainly has more objective reality in itself than those by which finite substances are represented."

Moreover, when thinking about an idea's degree of reality in relation to its source, the Meditator realizes "by the natural light that there must be at least as much reality in the total and efficient cause as in its effect." The cause of an idea has to be at least as real as its effect. The objective reality of God—the idea of God—includes omnipotence, omniscience, the eternal and infinite. Is there a formal reality to this idea? In other words, is there a mind-independent entity that attaches to "God"? Perhaps the cause of this idea has only objective reality.

The properties of this idea work against the cause being mind dependent. Indeed, the cause of the idea of perfection—included in God's attributes or essential nature—has to be at least as real as the idea itself. Consequently, God must be real.

The Meditator wonders if he could potentially possess the attributes assigned to God. The scope of his knowledge, after all, is increasing. Perhaps he could increase his knowledge "to infinity." This idea is rejected, however, since "this very fact of gradual increase is an infallible index of imperfection." The Meditator's knowledge can surely improve but by definition cannot reach perfection. The actual perfection contained in the idea of God, on the other hand, cannot be increased—it is already complete.

In connection with the levels or degrees of reality are levels of being: infinite, finite, and mode. The latter two are dependent on the first. So if God is an infinite substance, then finite substances and modes (characteristics of thought, e.g., willing, doubting) are dependent on him. Consequently, the Meditator is not the author of himself but is created by God. The Meditator's idea of God has been "stamped" on his mind by God himself.

The Meditator concludes from all this that God cannot be a deceiver. A further consequence is that the errors the Meditator makes are entirely his own, at least so far as God is concerned.


Descartes raises a major epistemological problem: How can I know that my ideas resemble anything outside me? The Meditator can be assured his ideas are true. This does not guarantee, however, that they accurately represent anything—if there is anything else independent of his mind. This question cannot be answered, however, before the Meditator can be assured God exists and is not a deceiver. After all, if God is a deceiver then the Meditator could not rely on clear and distinct ideas as an epistemological standard.

It is worth noting that Descartes's use of the phrase natural light of reason is that which is self-evident. This is also the characteristic of clear and distinct ideas. This standard was uncovered upon analysis of the steps that led to the Cogito and also serves to achieve the conclusion about God's existence in the Third Meditation:

  1. I have an idea of God as an infinitely perfect being.
  2. The idea must have a cause.
  3. The cause of the idea (the formal reality) must have at least as much reality as is in the effect (the objective reality, i.e., my idea).
  4. Therefore, my idea of God is neither innate nor self-produced.
  5. If the cause of my idea of God were something other than God, then the cause of the idea would be less real than the idea itself (the effect).
  6. Therefore, the cause of my idea must be infinitely perfect.
  7. Therefore, God exists.

Although the Meditator does not answer the epistemological question raised, he does take an important step in that direction. First, God exists. Moreover, God has created his essence and existence. God's attributes guarantee he is not a deceiver. Consequently, if there are mind-independent things to be known, the Meditator can, in principle, know them. The clear and distinct criterion is preserved.

A major problem arises in the Third Meditation, one that is suggested and responded to in the Fourth Objections and Replies. Antoine Arnauld mentions Descartes argues in a circle, and states "we can be certain that what we clearly and distinctly perceive is true, only if God exists, and we can be certain that God exists, only because we clearly perceive it." Descartes's reply is that there is a distinction between what is remembered as having been clearly and distinctly perceived and what is presently clearly and distinctly perceived. There are two problems with this response. One is that he seems to contradict this distinction elsewhere (see the Second Replies) by requiring present perceptions be validated by God. The other is that it is not at all obvious how God validates the memory of past perceptions. Not satisfied with Descartes's reply, this criticism has preoccupied scholars ever since.

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