Peirce on Cartesian Doubt

According to Peirce, Descartes’ methodological doubt violates Peirce’s basic rule that inquiry must begin with real doubt. In Peirce’s words:

Some philosophers have imagined that to start an inquiry it was only necessary to utter a question whether orally or by setting it down upon paper, and have even recommended us to begin our studies with questioning everything! But the mere putting of a proposition into the interrogative form does not stimulate the mind to any struggle after belief. There must be a real and living doubt, and without this all discussion idle (CP 5.376).

The central question here is the meaning of ‘doubt.’ For we cannot very well tell whether a given inquiry is genuine or not unless we know the criteria of "real and living doubt." Unfortunately Peirce himself is not very helpful. In "The Fixation of Belief," for instance, where he treats the problem of doubt in the most detail, he distinguishes belief from doubt on psychological grounds:

Doubt is an uneasy and dissatisfied state from which we struggle to free ourselves and pass into the state of belief; while the latter is a calm and satisfactory state which we do to wish to avoid, or to change to a belief in anything else (CP 5.372).

According to this conception, doubt is apparently known because is a dissatisfactory state, an irritant which causes mental activity or inquiry.

Although Peirce was sensitive to some of the difficulties involved in treating doubt as dissatisfaction and made attempts to overcome them (see CP 5.394), in 1903 he admitted that his early theory was overly psychological and, hence, inadequate (5.28). Fortunately, there is another, more adequate conception of doubt in Peirce. Put crudely, this other conception is that doubt is the blocking of a habit of action, or, as Peirce says, doubt is "the privation of a habit" (CP 5.417). Although Peirce’s language here is obscure, I think the conception can be clarified in such a way

that Peirce’s theory of doubt and inquiry make good sense. Furthermore, I think Peirce’s view that doubt is a privation is the logical conception he wished to defend when, in 1903, he criticized the early theory. In order to see this second notion of doubt more clearly, let us step back for a moment to get the overall view of the role of belief in knowledge according to Perce.

Two basic principles of Peirce’s theory of knowledge are: (1) belief is a habit of action which may be present even though the individual is not conscious of his belief, and (2) man cannot see beyond his beliefs to the facts of reality. The first principle is well known and may be passed over quickly. Briefly, Peirce’s view is that ‘A believes p’ is always analyzable into a dispositional proposition relating to A’s potentiality to act in certain ways in certain circumstances (CP 5.371, 5.398). The second principle, although also well known, calls for somewhat closer scrutiny. According to Peirce: "All you have any dealings with are your doubts and beliefs, with the course of life that forces new beliefs upon you and gives you power to doubt old beliefs (CP 5.416). Peirce’s main reason for this is the backbone of his criticism of intuition in the 1868 papers. According to Peirce, although ‘I believe p’ and ‘It is true that p’ differ in meaning, I cannot distinguish between them in the knowledge situation. That is to say, I have no criterion by which to distinguish my true beliefs from the false ones, for, so long as they are my beliefs, I believe them to be true. Hence, any claim that p is true reduces to a belief-statement of the form ‘A believes p.’ As Peirce put it:

The most that can be maintained is, that we seek for a belief that we shall think to be true. But we think each one of our beliefs to be true, and, indeed, it is a mere tautology to say so. (CP 5.375; Peirce’s italics).

According to Peirce, this principle even applies to perceptual judgments (CP 5.180 ff.). Briefly, Peirce’s view is that propositions framed on the basis of percepts and past experience are the only cognitive parts of perception, for only they can be true or false and communicated. Hence, when we perceive an object, we do not have direct knowledge of that object. Rather, we believe a proposition about the perception. Hence, our view of reality as given in perception is what we believe reality to be and not necessarily what reality actually is.

These two principles — that belief is a habit of action and that we cannot see beyond our beliefs — provide the framework for Peirce’s theory of inquiry and doubt. According to Peirce, knowledge is a more or less unified body of beliefs accepted by the community to organize experience and to help us predict the future. Although the final goal is truth, we can never verify beliefs by comparing them to non-mental facts in reality, for we can never look beyond our beliefs about the world tot he world itself. Rather, verification takes place by acting on our beliefs and seeing whether experience fits our expectations. If the belief in question is true, no perceptual proposition forced on us in the future will contradict it. If, however, the belief is false, there will come a time when acting on the belief will be thwarted by experience; that is, we will be forced to believe a perceptual proposition which contradicts our belief. When this happens we conduct inquiries, i.e. we re-examine the situation and either reject the disconfirming instance, revise the old belief, or scrap it altogether and replace it with a new one. The stage which concerns us here is the thwarting of the belief by experience, which is doubt. Basically doubt is the awareness of an incompatibility between two beliefs, one accepted on the basis of previous experience and one forced on us by the perceptual situation. This view of doubt is what Peirce had in mind when he wrote in 1908 that:

Every inquiry whatsoever takes its rise in the observation . . . if some surprising phenomenon, some experience which either disappoints an expectation, or breaks in upon some habit of expectation of the inquisiturus; and each apparent exception to this rule only confirms it. (CP 6.469; cf. 7.194).

Peirce’s use of the word ‘every’ in this passage implies that all doubt arises from the appearance of a negative instance of a hypothesis. In the light of what Peirce says in other places, however, this is an overstatement. Although he seems to believe that most cases of doubt arise through disconfirmation, he recognizes another important case as well, namely, the case where the inconsistency is between non-perceptual propositions I believe without being aware that they are inconsistent. For example, I may believe that a lead ball dropped from the mast of a moving ship will fall toward the stern instead of at the base of the mast and also believe that the earth moves on its axis. In such a case the inconsistency is not between a perceptual and non-perceptual proposition but rather between two non-perceptual propositions. Whereas doubt is forced on me in the case of a negative instance, doubt in the case of incompatible non-perceptual beliefs can arise by reflection independent of over action and experimentation. It is this latter case that Peirce has in mind when he says:

It will be wholesome enough for us to make a general review of the causes of our beliefs; and the result will be that most of them have been taken upon trust and have been held since we were too young to discriminate the credible from the incredible. Such reflections may awaken real doubts about some of our positions. (CP 5.376 n)

Combining these two cases of doubt, Peirce’s conception of doubt can be stated as follows: A doubt p, if, and only if, A is led to believe p and some other proposition q, and A is aware of an inconsistency between p and q. Since ‘A believes p’ means that A has a dispositions to act in certain ways, it follows that doubting p involves the awareness on A’s part that is disposed to act in incompatible ways in a given situation. Hence, A’s doubting p implies indecision and suspension of action what can only be cleared up by inquiry, or, in Peirce’s words, doubt in this sense is the "privation of a habit." This conception of doubt has nothing to do with psychological matters. Rather, it rests on the logic of belief and the view that man has no direct knowledge of non-mental facts.

So far I have concentrated on the conception of doubt in Peirce. Let me now turn to the relation between doubt and inquiry. Why does Peirce feel that real inquiry has to begin with doubt? Here again we find Peirce confusing logical and psychological considerations despite his avowed refusal to do so. On the psychological side he seems to feel that, without the presence of doubt, the danger exists that the proposition examined will prejudice the investigation and, hence, turn the study into a whitewash (CP 5.376 n). On this level, Peirce’s doctrine of inquiry rests on the psychological principle that doubt reinforces objectivity by helping the investigator to isolate the belief under examination. Although this defense of Peirce’s doctrine is weak, he also has logical grounds for holding that inquiry must begin with doubt. This strain of Peirce’s thought first appears in 1868:

A person may, it is true, in the course of his studies, find reason to doubt what he began by believing; but in that case he doubts because he has a positive reason for it, and not on account of the Cartesian maxim (CP 5.265).

The important point here, as Broyles has pointed out, is that doubt must be based on a "positive reason." That is, the investigator must be able to justify his inquiry by clearly stating the ground on which the belief being examined is inadequate. Doubt justifies inquiry because doubt is the awareness of an incompatibility between two beliefs. Hence, when challenged to justify the inquiry, the investigator can point to the contradictory beliefs in the system of knowledge. If, however, the investigator did not begin with real doubt, his work is idle, for he has wasted his time on a belief which he had no reason to believe was inadequate. Seen in this light, Peirce’s doctrine that inquiry must start with doubt is a principle of the logic of justification. According to Peirce, rationality demands that we do not conduct inquiries casually, but always with a reason. Unless such a reason can be given in the form of a contradiction in the structure of knowledge, weare wasting our time. When our beliefs are adequate, they are adequate, and one who says that they are not is crying in the wilderness.

I now wish to consider Peirce’s charge that, on the basis of Peirce’s account of doubt and inquiry, Descartes is guilty of sham doubt and, hence, that his inquiry is worthless. As Descartes makes clear in Meditation I, his aim is to establish the sciences on a firm foundation rather than on the opinions he believed in his youth. The firm foundation he finally arrives at is the co gito and, from this, the existence of a good and all-powerful God. His procedure is to use the method of doubt to which Peirce so strenuously objects. Descartes says that no proposition which he is capable of doubting can provide the firm foundation he seeks. He applies this criterion to classes of propositions, since the undertaking would be endless if he considered each proposition singly. In Descartes’ words:

. . . I ought no less carefully to withhold my assent from matters which are not entirely certain and indubitable than from those which appear to me manifestly to be false, if I am able to find in each one some reason to doubt, this will suffice to justify my rejecting the whole.4

First, he applies his method of doubt to sensory propositions in general, then to the propositions "that I am here, seated by the fire, attired in a dressing gown, having this paper in my hands and other similar matters," that is, the class of propositions attested to by his own present sense experience. These are shown to be dubitable by the possibility that Descartes is dreaming. Descartes argues that, since it is possible that he is dreaming he has paper in his hands and is sitting beside the fire, it is not indubitable that what his senses report is actually the case. Finally, Descartes considers mathematical propositions and statements such as ‘Extension exists’ and ‘I have hands and sense organs’. These propositions, according to Descartes, are true even in dreams and, hence, are not made dubitable by the possibility that he is dreaming. They are, however, still dubitable, Descartes says, for it is possible that God is really an evil demon who makes me believe all these propositions when, in fact, they are false.

It is at this point that Peirce’s charge becomes pertinent. Descartes, Peirce holds, does not really doubt any of these propositio.ns, for Descartes nowhere points out a contradiction in that which experience has led him to accept. The only possible candidates Descartes gives as "positive reasons" are the dream and the evil demon. Yet, by Descartes’ own admission, he does not really believe that he is dreaming or that there is a demon. In other words, Descartes is merely pretending that mathematics and the truths of immediate sense experience are false. Hence, according to Peirce, any mental effort spent on re-establishing mathematics and sense experience is a waste of time, since Descartes continues to believe what he says he doubts.

Peirce’s charge seems to make good sense, but actually it is misplaced. Let us concentrate on Descartes’ apparent doubts about the paper in his hands. According to Peirce, Descartes claims the following:

(1) I doubt that J have a piece of paper in my hands.

What Descartes is claiming, however, is:

(2) It is possible for me to doubt that I have a piece of paper in my hands.

That Descartes is claiming the possibility of doubt rather than doubt itself is clear. For instance, in summarizing the results of Meditation I, Descartes says, "I shall proceed by setting aside all that in which the least doubt could be supposed to exist, just as if I had discovered that it was absolutely false."5 Clearly the claim is (2) and not (1). Furthermore, in the statement of the rule of doubt itself, Descartes says he will withhold assent from matters "not entirely certain and indubitable," The clear implication is that Descartes is not merely seeking true propositions as the firm foundation of science; rather he wants absolutely true propositions, i.e., propositions about which we cannot possibly be mistaken in the sense of logical possibility.

Now, admittedly it is difficult to see how Descartes could doubt that he has a piece of paper in his hands and yet continue to write Meditation I. He might put his pen to the supposed paper and find that no mark is registered. Or he might attempt to tear it for some reason and discover that it does not tear easily as paper ordinarily does. In either case, Descartes would be justified in claiming to doubt his sensory report; but surely if he doubted that he has paper before him, it would be insane for him to continue writing and telling of his doubts. However, there is no difficulty connected with Descartes claiming that it is possible to doubt the existence of the paper. In order to show this, Descartes has only to point out the possibility of one situation in which he has the sense perception of paper in his hands while in fact there is no paper. One such case, as Descartes correctly points out, is the situation in which we dream we are beside the fire writing on paper when, as a matter of fact, we are sleeping in bed. In short, the possibility that Descartes is dreaming is sufficient to show that Descartes’ actual claim is true. Thus, once we become clear about Descartes’ claims, we find that he does have sound reasons which would justify his inquiry.

The point may be put in another way: according to Descartes, knowing always includes indubitable awareness of the truth of the proposition. Hence, in order for a belief to pass as knowledge for Descartes, the falsity of the belief must be inconceivable. Now, when Descartes considers immediate sense experience, he finds that he could have the same perceptions he now has yet in reality be asleep dreaming. Hence, for Descartes it is conceivable that he is not sitting by the fireplace with a piece of paper in his hands. He could possibly be in bed dreaming. Thus, in his sense of ‘know’, Descartes does not know that he has paper in his hands, for his sense impressions do not tell him indubitably that he does. Seen in this light, Peirce’s mistake is clear. According to Peirce, Descartes did not really doubt; he actually believed, and hence his inquiry was a sham. But this, of course, misses Descartes’ point. What Descartes is interested in showing is that he does not know about reality through perception in his sense of ‘know’. And this he snows-acrequately by the possibility that he is dreaming. Since he may be dreaming, he does not know with certainty that he is holding a piece of paper. Furthermore, Descartes can accept Peirce’s charge that he continues to believe mathematical and sensory propositions without harm. Descartes merely has to point out that there is a difference between believing and knowing, and that, although he continues to believe in sensory reports, they still do not pass as knowledge in the Cartesian sense. In short, Descartes’ doubts are about knowledge claims in his sense of ‘know’ and not about the truth of beliefs, whereas Peirce’s criticism rests on the view that Descartes claims to be doubting beliefs and not merely knowledge claims. Peirce, in other words, misunderstands Descartes.

This conclusion is enlightening in another way. Peirce criticized Descartes for ending up by affirming what he began by doubting. For Peirce, this shows that Descartes is really cheating in that the beliefs apparently doubted have in fact guided the entire investigation. That is, for Peirce, Descartes is merely giving a whitewash. But, when one understands what Descartes is doing, it becomes clear that he never actually doubted the propositions in Meditation 1. All he intended to show was that every proposition other than the cogito is dubitable. The fact that Descartes ends up accepting many of the propositions he supposedly doubted is the result of Descartes’ conviction that these beliefs have been placed on a solid foundation. That is, they have been certified; he has what he takes to be good reason for believing they are true. In other words, Descartes is not really looking for new factual knowledge; he is seeking to place his present knowledge on what he takes to be an acceptable basis.

The problem, I think, is that Peirce misconstrues the aim of Descartes’ inquiry. According to Peirce, inquiry is the struggle to attain new beliefs after the recognition of a contradiction in the system of knowledge. Thus, for Peirce, inquiry is the search for new factual knowledge, i.e., new hypotheses. This conception of inquiry, however, fails to take account of Descartes’ investigation.6 For Descartes is not trying to discover new hypotheses to account for experience. His problem is philosophic in character rather than scientific. That is, he starts from the assumption that man has

knowledge about the world, then attempts to clarify the nature of this knowledge and show how it is justified. That Descartes ends up by affirming that he is not now dreaming and that there is no evil demon is not surprising, for, Descartes would claim, his investigation has shown in what way mathematical and sensory propositions are known.

So far, I have restricted myself to showing that Peirce misunderstands Descartes’ method of doubt and the nature of his inquiry. In closing, I would like to consider briefly the broader question of whether this means that Descartes’ procedure is acceptable or, at least, innocuous according to Peirce’s account of .inquiry and knowledge. I think that it is clearly not acceptable. From Peirce’s point of view, there is still a fundamental mistake in Descartes’ Meditations, namely, Descartes’ conception of the nature of knowledge. As we have seen, Descartes will not accept a proposition as knowledge unless he is indubitably aware of the truth of the proposition. Hence, for Descartes, ‘A knows p’ is false unless A is indubitably certain that p is true. According to Peirce, such a conception of ‘know’ is unacceptable, for it entails that man knows nothing. Basically, Peirce’s reason is the principle considered in the first part of this paper, namely, the doctrine that man cannot look beyond his beliefs to non-mental facts. For Peirce, since man cannot see beyond his beliefs, he can never be directly aware that the state of affairs depicted by a given proposition is in fact real. Thus, the most one can justifiably say is that he believes the proposition is true, always leaving open the possibility that it will be refuted by some future experience. Moreover, one’s awareness that a given proposition is true does not entail that the proposition is in fact true no matter how intense the conviction, since, for Peirce, knowing entails believing and believing is compatible with being mistaken. Hence, from Peirce’s point of view, you can never know any proposition about reality with absolute certainty, or, to put it differently, man knows nothing in Descartes’ sense of ‘know’.

So far, I have restricted myself to showing that Peirce misunderstands Descartes’ method of doubt and the nature of his inquiry. In closing, I would like to consider briefly the broader question of whether this means that Descartes’ procedure is acceptable or, at least, innocuous according to Peirce’s account of .inquiry a.nd knowledge. I think that it is clearly not acceptable. From Peirce’s point of view, there is still a fundamental mistake in Descartes’ Meditations, namely, Descartes’ conception of the nature of knowledge. As we have seen, Descartes will not accept a proposition as knowledge unless he is indubitably aware of the truth of the proposition. Hence, for Descartes, ‘A knows p’ is false unless A is indubitably certain that p is true. According to Peirce, such a conception of ‘know’ is unacceptable, for it entails that man knows nothing. Basically, Peirce’s reason is the principle considered in the first part of this paper, namely, the doctrine that man cannot look beyond his beliefs to non-mental facts. For Peirce, since man cannot see beyond his beliefs, he can never be directly aware that the state of affairs depicted by a given proposition is in fact real. Thus, the most one can justifiably say is that he believes the proposition is true, always leaving open the possibility that it will be refuted by some future experience. Moreover, one’s awareness that a given proposition is true does not entail that the proposition is in fact true no matter how intense the conviction, since, for Peirce, knowing entails believing and believing is compatible with being mistaken. Hence, from Peirce’s point of view, you can never know any proposition about reality with absolute certainty, or, to put it differently, man knows nothing in Descartes’ sense of ‘know’.

This is very strong reason for rejecting Descartes’ conception that knowledge must be indubitable. Unfortunately, I think Peirce only confuses the issues by concentrating on Descartes’ methodological doubt. The Cartesian doubt is only a test which an alleged item of knowledge must pass in order to be the genuine article. The real problem is with the view of ‘know’ itself, the view that knowledge has to be indubitable, for, even if Descartes has sound reasons for being able to doubt what he doubts, he is still in error about knowledge itself. In short, what is wrong with Meditation I from Peirce’s standpoint is not Descartes’ method, but rather the conception of knowledge underlying the method. The method which Descartes uses and Peirce misunderstands is quite acceptable once we accept Descartes’ requirements for knowledge, for, as I have tried to show, Descartes does have sound reasons for doubting that he knows in his sense of ‘know.’ The Cartesian salad, in other words, may be indigestible, but, given Descartes’ palate, not all that difficult to swallow.7

State University of New York at Albany

NOTES

1. James R. Broyles, for instance, agrees with Peirce. See his "Charles S. Peirce and the Concept of Indubitable Belief," Transactions of the Charles S. Peirce Society, vol. I, no. 2, pp. 82 ff.

2. This view lies at the heart of Peirce’s doctrine that true propositions are those which the community believes in the long run (5.311). Since no individual can distinguish his true beliefs from his false beliefs, he cannot decide truth by examining his own consciousness; he must appeal to some wider community. The necessity for defining truth as communal is summed up in Peirce’s remark "that individualism and falsity are one and the same" (5.402 n).

3. Loc. cit.

4. The Philosophical Works of Descartes, ed. E. S. Haldane and G. R. T. Ross (New York, 1955), I, p. 145.

5. Ibid., p. 149.

6. And, I might add, Peirce’s own epistemological inquiries.

7. I wish to thank Edward H. Madden for suggestions on an earlier version of this paper.