Markie (1979) Clear and distinct perception and metaphysical certainty

Markie, Peter (1979). Clear and distinct perception and metaphysical certainty. Mind 88 (349):97-104.

1

Recent commentators on Descartes have been concerned with clarifying the relationship between two important Cartesian concepts: clear and distinct perception and metaphysical certainty.

It is generally agreed that to perceive a proposition clearly and distinctly is to apprehend it in a particular manner and that a person is metaphysically certain of a proposition just in case he does not have any reason to doubt it.

Yet, it is not clear how Descartes understands the relationship between a person's clear and distinct perception of a proposition, on the one hand, and his metaphysical certainty of it on the other. My aim in this paper is to show that one interpretation of Descartes' position on this matter is incorrect

i. The interpretation that interests me attributes this principle to Descartes:

(i) If S clearly and distinctly perceives p at t, S is metaphysically certain of p at t.

Some well-known commentators have adopted this interpretation at one time or another. Harry Frankfurt says that according to Descartes:

To perceive something clearly and distinctly... is to be aware of grounds for believing it so complete that no basis for doubt remains.

Since Frankfurt notes that not having a reason to doubt a proposition is equivalent to being metaphysically certain of it, his statement suggests that he attributes (i) to Descartes. Anthony Kenny seems to have (i) in mind when he places himself in Descartes' position and writes:

Whenever I clearly and distinctly perceive something I cannot help judging that it is so, and this will be a true judgment made on the best possible grounds.

In one of his papers, Willis Doney also presents (i), claiming that, for Descartes, 'Clear and distinct perceptions were never subject to doubt.'

This interpretation is open to serious objection. Principle (i) is inconsistent with one of Descartes' most important claims; we do not have enough textual evidence to justify our attributing it to Descartes under these conditions.

2

To make my objection, I shall first extract from Descartes' statements a somewhat vague version of the claim that interests me and then clarify that claim to show that it is inconsistent with (i)

In the Fifth Meditation, Descartes writes:

For although I am of such a nature that as long as I understand anything very clearly and distinctly, I am naturally impelled to believe it to be true, yet because I am also of such a nature that I cannot have my mind constantly fixed on the same object in order to perceive it clearly ... it may happen meanwhile that other reasons present themselves to me, which would easily cause me to change my opinion, if I were ignorant of the facts of the existence of God, and thus I should have no true and certain knowledge, but only vague and vacillating opinions. Thus, for example, when I consider the nature of a [rectilinear] triangle, I . . . recognize quite clearly that the three angles are equal to two right angles, and it is not possible for me not to believe this so long as I apply my mind to its demonstration; but so soon as I abstain from attending to the proof, although I still recollect having clearly comprehended it, it may easily occur that I come to doubt its truth, if I am ignorant of there being a God.

Descartes acknowledges that he is never able to doubt a proposition while clearly and distinctly perceiving it, but claims that until he knows God his clear and distinct perception of some propositions, such as the theorem that the angles of a triangle equal two right angles, fails to give him 'true and certain knowledge'.

Descartes makes what is essentially the same point in discussing an atheist's epistemic abilities. He considers Mersenne's statement that: While an Atheist knows clearly and distinctly that the three angles of a triangle are equal to two right, yet he is far from believing in the existence of God .... (HR II, 26)

Descartes replies:

That an atheist can know clearly that the three angles of a triangle are equal to two right angles, I do not deny, I merely affirm that, on the other hand, such knowledge on his part cannot constitute true science, because no knowledge that can be rendered doubtful should be called science. Since he is, as supposed, an Atheist, he cannot be sure he is not deceived in the things that seem most evident to him.... (HR II, 39).

Descartes is willing to admit that the atheist can clearly and distinctly perceive the theorem at hand.' He insists, however, that due to the atheist's ignorance of God, the atheist's clear and distinct perception does not provide him with the certainty he requires for scientific knowledge.

These passages justify the attribution of this somewhat vague but important principle to Descartes:

(2) Until S has knowledge of God, S's clear and distinct perception of some propositions fails to make him certain of them in a way required for scientific knowledge

The importance of this principle for Descartes is clear: his acceptance of it provides him with his motivation for trying to obtain knowledge of God in the Third Meditation. The principle itself is vague, however. It is not clear how we are to understand the phrase 'certain of them in a way required for scientific knowledge'. As commentators have noted, Descartes employs a number of different notions of certainty; to name just a few:

psychological certainty (not being able to doubt a proposition),
metaphysical certainty (not having a reason to doubt a proposition) and
moral certainty (being justified in adopting a proposition for practical purposes).

Before we can fully appreciate (2) and, in particular, determine whether (2) is inconsistent with (i), we have to determine how Descartes understands the notion of certainty involved in (2).

Once we consider another one of Descartes' statements, it becomes clear that he understands (2) so that it is inconsistent with (i). Principle (2) is inconsistent with (i) when the notion of certainty involved in (2) is taken to be that of metaphysical certainty, and this is just how Descartes understands (2). Consider his statement to Mersenne:

To begin with, directly we think we rightly perceive something, we spontaneously persuade ourselves that it is true. Further, if this  conviction is so strong that we have no reason to doubt concerning that of the truth of which we have persuaded ourselves, there is nothing more to enquire about; we have here all the certainty that can be reasonably desired .... and this persuasion is clearly the same as perfect certitude (HR II, 41).

Descartes says that if he does not have a reason to doubt a proposition, that is, if he is metaphysically certain of it, he has all the certainty regarding it he can reasonably desire. In writing, then, of the certainty required for scientific knowledge, he evidently has metaphysical certainty in mind. Thus, he understands (2) so that it contradicts (i).

Of the commentators I am considering only Kenny considers (2) and, appealing to a kind of certainty other than metaphysical certainty, he interprets (2) so that it is consistent with (i). To establish my claim that (2) is to be interpreted in terms of metaphysical certainty, I must then show that Kenny is mistaken. He interprets (2) as involving a kind of certainty stronger than metaphysical certainty, something he calls 'Cartesian certainty'. As I understand him, for p to be a Cartesian certainty for S at t is for p to be a metaphysical certainty for S at t and such that there is no later time, t', at which p is a metaphysical uncertainty for S (Kenny, p. I92). Examination reveals that (2) is consistent with (i) when (2) is clarified in terms of Cartesian certainty.

As support for his interpretation of (2), Kenny cites the passage already considered from the Fifth Meditation (p. 98). Kenny interprets Descartes as claiming that when he is ignorant of God, his clear and distinct perceptions are not Cartesian certainties, though they are metaphysical certainties.

He takes Descartes to be saying that before he knows God his clear and distinct perceptions are metaphysically certain for him when he has them, but that later, when his perceptions cease, those propositions are made metaphysically uncertain for him by the hypothesis that God is a deceiver. Hence, he does not obtain Cartesian certainty of those propositions by clear and distinct perception.

Consideration of a number of points reveals that Kenny's interpretation of (2) is incorrect. First of all, his interpretation is not conclusively established by the Fifth Meditation passage. That passage can be plausibly interpreted so that Descartes has metaphysical certainty in mind rather than Cartesian certainty. One might reasonably take Descartes' position to be the following. Prior to knowing God, when he is clearly and distinctly perceiving a proposition such as the theorem mentioned in the passage, he cannot bring himself to doubt it. Nevertheless, he has a reason to doubt it and, so, is metaphysically uncertain of it. Furthermore, if he ceases to perceive the theorem clearly and distinctly, he will then be able to realize that he has a reason to doubt the theorem and to doubt it.

Psychological Certainty ^[각주:1]-> Metaphysical Cetainty ^[각주:2]-> Cartesian certainty

Having a reason to doubt is irrelevant to mental state

Besides not being conclusively established by the Fifth Meditation passage, Kenny's interpretation has faults which make it less preferable than my clarification of (2) in terms of metaphysical certainty.

On Kenny's interpretation, Descarte claims that we require something more than metaphysical certainty for scientific knowledge, we require Cartesian certainty. This claim is inconsistent with the passage con sidered earlier in which Descartes claims that once we have metaphysical certainty there is nothing more to enquire about.

Kenny's interpretation also forces us to attribute an extremely implausible position to Descartes: that when he overcomes his epistemic limitations by coming to know God, he reaches a point where his clear and distinct perception of a proposition at a time makes that proposition a Cartesian certainty for him at that time. This is very implausible. Not even a knowledge of God could place Descartes in a position where his clear and distinct perception of a theorem insured that he would not at some later time cease clearly and distinctly perceiving the theorem, forget his evidence for it, and so have a reason to doubt it.

I conclude, then, that (2) is correctly interpreted in terms of the notion of metaphysical certainty and, hence, that (i) contradicts one of Des cartes' most important claims. We, therefore, need strong evidence for (i) if we are to be justified in attributing it to Descartes; there must at least be passages in which Descartes explicitly states (i) or some principles which imply it. I shall now argue that we do not have such evidence.

3

one of the commentators I mentioned earlier cites a passage in which Descartes explicitly states (i) and, from my own examination of Descartes' works, there do not appear to be any. These commentators do argue that Descartes presents other principles which commit him to (i), however.

Doney and Frankfurt claim that Descartes identifies his clear and distinct perception of a proposition with his intuition of it (Doney, p. 327; Frankfurt, p. 2io) and Doney cites passages in the Rules in which Descartes claims his intuitions are always metaphysically certain (Doney, p. 327). This suggests the following argument. There is strong textual evidence for ascribing to Descartes:

(3) If S intuits p at t, S is metaphysically certain of p at t.

Since Descartes identifies intuition and clear and distinct perception, his acceptance of (3) commits him to (i).

Descartes may in fact adopt (3); he says that whenever he intuits a proposition he is 'wholly freed from doubt' (HR I, 7). [including metaphysical certainty] Yet, there do not seem to be any passages in which Descartes identifies clear and distinct perception and intuition. Doney and Frankfurt do not cite any textual support for their view, and Descartes' definition of intuition does not support them.

By intuition I understand,.. the conception which an unclouded and attentive mind gives so readily and distinctly that we are wholly freed from doubt about that which we understand (HR I, 7)

Even if we take the phrase 'readily and distinctly' here to be synonymous with 'clearly and distinctly', Descartes' definition is that to intuit a proposition is to perceive it clearly and distinctly in such a way that we are wholly freed from doubt about it. For all this tells us, Descartes may take clear and distinct perception to be only a necessary condition of intuition.

Another passage is plausibly interpreted so as to suggest that Descartes takes clear and distinct perception to be a necessary, but not a sufficient, condition of intuition.

two things are requisite for mental intuition. Firstly, the proposition intuited must be clear and distinct; secondly, it must be grasped in its totality at the same time and not successively (HR I, 33)

I take Descartes to be claiming that to intuit a proposition he must clearly and distinctly perceive it and grasp all of its parts at once. While it is admittedly unclear how we are to understand the second condition, his statement suggests he does not identify clear and distinct perception and intuition.

A second argument can be drawn from statements by Frankfurt and Kenny. They claim that Descartes identifies his clear and distinct perception of a proposition with his perception of it by the natural light (Frankfurt, p. 2I2; Kenny, pp. I77-I78) and Kenny cites textual evidence to show that Descartes believes his perception of a proposition by the natural light makes him metaphysically certain of it (Kenny, p. I78). This suggests the following argument. There is textual support for attributing to Descartes:

(4) If S perceives p by the natural light at t, S is metaphysically certain of p at t.

Since Descartes identifies his perception of a proposition by the natural light with his clear and distinct perception of it, his acceptance of (4) commits him to (i).

There is textual support for one premise of this argument. In the Principles, Descartes restates his conclusion from the Meditations that all his clear and distinct perceptions are true but rephrases it as:

the light of nature or the faculty of knowledge which God has given us, can never disclose any object which is not true inasmuch as it comprehends it, that is, inasmuch as it apprehends it clearly and distinctly (HR I, 23I).

By stating his conclusion in this way, Descartes seems to identify his clear and distinct perception of a proposition with his perception of it by the natural light.

Nevertheless, it is far from clear that Descartes accepts (4). To show that he does so, Kenny cites the passage:

When I say that I am so instructed by nature, I merely mean a certain spontaneous inclination which impels me to believe in this connection, and not a natural light which makes me recognize that it is true. But these two things are very different; for I cannot doubt that which the natural light causes me to believe to be true, as, for example, it has shown me that I am from the fact that I doubt, or other facts of the same kind. And I possess no other faculty whereby to distinguish truth from falsehood, which can teach me that what this light shows me to be true really is not true, and no other faculty that is equally trustworthy (HR I, i6o).

Descartes states here that he cannot doubt propositions that the natural light causes him to believe. According to Kenny, he is claiming to be metaphysically certain of any proposition he perceives by the natural light.

I think this passage can be plausibly interpreted as Kenny suggests, but it has at least two other plausible interpretations that do not commit Descartes to (4). We might take Descartes to be claiming, not that he lacks a reason to doubt any proposition he perceives by the natural light, but that he is psychologically unable to doubt such propositions. His distinction between being instructed by nature to believe a proposition and his perceiving one by the natural light is then that in the latter case, but not in the former, he is psychologically unable to doubt the pro position at hand.

There are a number of points in favour of this interpretation. In the passage before us, Descartes does not explicitly state that he has no reason for doubting propositions he perceives by the natural light; he only says he cannot doubt them. Also, in the Fifth Meditation, he claims that he is psychologically unable to doubt a proposition he clearly and distinctly perceives (HR I, I84). Assuming that he identifies the natural light with his faculty of clear and distinct perception, this suggests that he thinks he is psychologically unable to doubt propositions he perceives by the natural light. Finally, in the Sixth Meditation, Descartes notes that a number of the beliefs he found to be doubtful in the First were ones he was instructed to believe by nature (HR I, i88). Despite this instruction, he was able to doubt those beliefs at the end of the First Meditation by relying on the hypothesis of a deceptive god. This suggests that he thinks he is psychologically able to doubt propositions he is instructed to believe by nature.

As another alternative interpretation, we might take Descartes to be claiming that he is metaphysically certain of some, but not all, of the propositions he perceives by the natural light. The ones he has in mind are the ones he perceives in such a way that he intuits them. There are a couple of points in favour of this interpretation. First of all, we have seen that Descartes regards his intuition of a proposition as involving his clear and distinct perception of it and so, presumably, his perception of it by the natural light. Second, as an example of the propositions that interest him here, Descartes presents the one that his doubting implies his existence and refers us to others of 'the same kind'. In the Principles, he states that the proposition that his doubting implies his existence is a common notion (HR I, 239), and in the Rules he says that he intuits common notions (HR I, 4I-42)

Neither of these arguments, then, provides substantial support for the view that Descartes accepts (i). Since there does not appear to be any other textual support for that view, and since (i) is inconsistent with an important claim Descartes does make, I conclude that Descartes does not accept that principle.

1. when he is clearly and distinctly perceiving a proposition such as the theorem mentioned in the passage, he cannot bring himself to doubt it [본문으로]
2. Nevertheless, he has a reason to doubt it and, so, is metaphysically uncertain of it.  [본문으로]