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Descartes 2

A Criterion for Certainty -- Clear and Distinct Ideas

At the beginning of Meditation III, Descartes summarizes what he knows. This leads him to reflect on the criterion for certainty. He says:

I'm certain that I am a thinking thing. Then don't I know what is needed to be certain of other things? In this first knowledge there is nothing but a clear and distinct grasp of what I affirm, and this grasp would surely not suffice to make me certain if it could ever happen that something I grasped so clearly and distinctly was false. Accordingly I seem to be able to establish the general rule that whatever I clearly and distinctly grasp is true. (Pg. 14)
There are two or three quite interesting things about this paragraph. One is how clever Descartes' procedure is for establishing a criterion for certainty. First he discovers three truths which can be known for certain. Then he examines one of them and finds a characteristic which makes it certain -- the clearness and distinctness of the ideas. The second point of interest is that Descartes has found something which was implicit in the original account of his discovery of sum res cogitans which is going to allow him to make progress in ways which we might not expect, namely this characteristic of ideas as "clear and distinct." As it turns out, there are other terms here which have the same characteristic. Res for example ("res" means "thing" in Latin) turns out to be an ordinary language expression for "substance." Substances, which have some kind of independent existence, and properties, which depend on substances, represent important philosophical machinery which Descartes will use in his proof for the existence of God. The third point of interest here is what "clear" and "distinct" mean. Clearly there is an analogy with sight and objects. The mind sees ideas with the same kinds of varying degrees of clarity with which the eye sees objects. (You might want to look at Cottingham's account of clarity and distinctness on Pg. 35 of The Rationalists.)

So, now we know that any truth composed of clear and distinct ideas can be known for certain. This leads Descartes on to a problem whose resolution adds more, indeed many more, truths to the foundation.

The Representational Theory of Perception

After establishing clarity and distinctness as the criterion for certainty at the beginning of Meditation III Descartes remarks:

But, in the past, I've accepted as completly obvious and certain many thoughts which I later found to be dubious. What were these thoughts about? The earth, the sky, the stars and other objects of sense.
The problem here is that if clarity and distinctness are the criterion of certain knowledge, don't I see the sun with complete clarity and distinctness? And the same with the sky, the earth and the stars? So, I should know these truths with complete certainty, but as Descartes says, he later found these things to be dubious. So, what is the difference between "sum res cogitans" and "I see the sun"?

Descartes answer to this question is this:

But what did I clearly grasp about these objects? Only that ideas or thoughts of them appeared in my mind. Even now, I don't deny that these ideas occur to me. But there was something else that I used to affirm -- something that I used to believe myself to grasp clearly but did not really grasp at all; I affirmed that there were things beside me, that the ideas in me came from these things, and that the ideas pefectly resembled those things. Either I erred here, or I reached a true judgement that wasn't justified by the stength of my understanding. (Pp. 14-15)
So, the answer seems to be this. There was in Descartes' judgement about the sun some elements which were clear, and some other things which were not. The clear element is that the image or idea of the sun is presented to him. The other elements involve these claim that there are things outside me which cause my ideas and so on. These, as it turns out are not clear. The difference, then, between "I am a thinking thing" and "I see the sun." is that the former contains ideas which are clear and distinct, while the latter contains some ideas which are clear and others which are not, and hence the composite judgement is not distinct. All of the clear elements can now be added to the foundation. So "I seem to see the sun." is known with as much certainty as "I am a thinking thing." The other elements -- there are things outside of me which cause my ideas and so on --involve claims which are part of a theory of perception sometimes called the causal or representational theory of perception. This is an important theory in the histroy of 17th and 18th century philosophy. We should consider its elements.

This theory holds that we directly perceive ideas which are caused by objects in the external world. This kind of representation theory is often contrasted with realist theories of perception. On a realist theory, I don't directly see the idea of a tree. Rather, I directly see the tree itself. Realist theories of perception simply involve a relation between the perceiver and the object of perception. Representation theories involve a three part relationship. There is theperceiver, the ideas which the perceiver directly perceives, and the object in the external world which the ideas represent and which cause the ideas.



There are strenghts and weakenesses to each kind of theory of perception. Realist theories have traditionally had trouble accounting for differences in perception, illusions, hallucinations and so forth. Representational theories can easily account for differences in perception and so on, but it is claimed that the price for doing so is making the external world inaccessible to perception! If all we see are ideas, then we do not directly perceive the objects the ideas represent. And this leads to a further problem. How do we know that ideas accurately represent those objects which we never perceive. Montaigne makes precisely these charges in his discussion of perception (Pg. 81 in reading in the class packet). In our times, Jonathan Bennett has dubbed the version of the representational theory which is open to this objection "The veil of Perception." He calls it this because the ideas are like a veil which prevents us from actually seeing the external world.

It is at least possible that both realist and representational theories can be interpreted in ways which avoid the difficulties which have been traditionally associated with them. Recently commentators have argued that Descartes (and a variety of other 17th century philosophers including Arnauld and Locke) do not understand the representational theory of perception in a way which leaves it open to these kinds of difficulties. Who has got it right -- the commentators who insist that Descartes is an adherent of the "veil of perception" theory or the new commentators who deny that he does hold this view? We will set this question aside, and simply note that much of what Descartes says seems to be compatible with the "veil of perception" view.

Descartes now begins his ascent from the foundation, trying to restablish the various truths which he had called into question along the way. Have we been informed of all the truths which lie at the foundation of this edifice of knowlede? The answer, as it turns out, is that we don't yet know all of them, even though the number has risen from one to two to three and then to a very large indeterminate number with the inclusion of all the "It seems that I..." kinds of claims. So, we will have to keep an eye out for yet other foundational truths. In the meanwhile, (in the first full paragraph on Pg. 15) Descartes is now concerned to recover the truths of mathematics. This is an important paragraph for it tells us about an interesting characteristic of clear and distinct ideas. Descartes asks himself if he does not grasp the simple truths of mathematics, such as 2 +3 = 5, to affirm their truth. Well, the reason he had for doubting these things was the God, or a malin genie could have made him so that he would go wrong even about what seems most obvious. He admits that an all powerful God could do this. But he continues:

But, when I turn to the things which I conceive myself to grasp very clearly, I'm so convinced of them that I spontaneously burst forth saying: "Whoever may deceive me, he will never bring it about that I am nothing while I think that I am something, or that I have never been, when it is now true that I am, or that two plus three is either more or less than five, or that something else in which I recognize an obvious inconsistency is true." (Pg. 15)
What is important about this passage is that it tells us that there are circumstances, particularly when Descartes is attending to such certain truths as the cogito or that 2 +3 = 5, when he cannot bring himself to doubt their truth. (This passage also gives us two more truths to add to the foundation -- "Even God cannot change the past." and "Contradictory propositions cannot be true." ) Against this immediate awareness of the certainty of truths which Descartes grasps "very clearly," the doubts about being deceived by God are slight and metaphysical. Still, Descartes claims, he ought next to consider whether God exists and whether He can be a deceiver. It seems that he must do this in order to rid himself of the malin genie.


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