Descartes’ Certain Knowledge of Himself as res cogitans and the Claim of the Second Meditation that Mind is better known than Body

§ 1: Descartes’ Certain Knowledge that he is as Thinking—What is It?

In my last set of notes I looked at Descartes’ argument that there are two beliefs which survive his general overturning and suspension of belief. These are his beliefs that he exists and that he thinks. In fact, it is misleading to describe these as two beliefs rather than one, for in reality Descartes claims to discover that he cannot doubt his existence, hence can be certain of it, insofar as he is thinking. Descartes discovers that he can have genuine, truly adequate rational assurance that he exists in his capacity as thinking, indeed, thinking right now, in an act of thinking the thought or proposition expressed by the sentence, “I exist.” As Descartes puts it, he may claim to know with certainty that “this proposition ‘I am, I exist’ is necessarily true whenever it is stated by me or conceived in my mind.” (p.24)

Descartes hopes to use this surely very meagre bit of certain, adequately grounded, hence truly rational belief as a basis for restoring the two general principles upon which rest all the individual substantive knowledge claims he has previously made; principles which, however, he has put aside in the course of his general overturning of belief and opinion. These two general principles are (1) that he has a capacity for genuine perceptual experience, which gives reliable, although of course not infallible access to empirical reality; and (2) that he has a capacity for a capacity for effective mathematical inference, in short, to calculate correctly, such that as a rule although not always he gets his mathematical inferences right. If he can legitimate these two principles, he will restore his entitlement to make the individual empirical and mathematical claims he has hitherto made. Thereby these will be restored to him as beliefs and opinions he truly rationally holds.

Now Descartes’ two surviving items of knowledge are clearly extraordinarily thin. How then are these two beliefs, or rather, this one double-barrelled belief, to serve as a basis for restoring all the beliefs and opinions which have not survived his general overturning and suspension of belief? In order to understand how Descartes can reasonably maintain this, it is essential to understand precisely just what these items of knowledge are, that is, what it is about them that enables them to survive the general overturning and suspension of belief. So I now want to explore this issue. And I want to do it in a fashion which might at first seem a little strange, namely, by determining why we do not find in the Meditations the famous sentence cogito, ergo sum (“I think, therefore I am”). For as we shall see, the reason why Descartes drops this memorable line in the later work has to do precisely with what permits his conviction that he is as thinking to survive all overturning of belief.

Descartes’ statement cogito, ergo sum occurs in the earlier work The Discourse on the Method of 1637.¹ So why does this great line not occur in the later work, the Meditations of 1641? There is in fact a good reason why it does not occur in the later work: by the time he came to write this work, Descartes had realised that this statement could be read in a very misleading way, that is, in a fashion which failed to capture the sense in which he could be certain of his own existence as a thinking thing. This misreading would then obscure how precisely his certain knowledge of himself as a thinking thing was to serve as fundamentum inconcussum (unshakeable foundation) for all his previous empirical and mathematical beliefs. Discussing why Descartes backed away from his famous statement is thus a good way of understanding just what the certainty of his own existence as thinking is.²

Descartes’ appreciation that there is something misleading about the statement cogito, ergo sum is manifest in the way he argues in the Meditations. Notice that in this later work he does not first establish the proposition, ‘I think’, and then, on the basis of this, the proposition ‘I am’. Rather, he first establishes the proposition ‘I am, I exist’ and then, independently of this, the proposition, ‘I think’. With regard to his existence, Descartes argues as follows: for all he thus far knows, all his empirical, arithmetic and mathematical beliefs could be wrong since for all he knows he could have been tricked into believing them by “some unidentified deceiver, all powerful and cunning, who is dedicated to deceiving [him] constantly” (p.24) even though these beliefs are all false. In consequence, he has adopted the policy of treating those of his beliefs and opinions which he can conceive of as false, even though he has the best possible grounds for them, as if they were false—see p.23. For these are precisely the beliefs and opinions into believing which this unidentified, supremely powerful and cunning deceiver could be tricking him. He then asks whether there is anything left over, which he cannot in this way ‘doubt’, i.e., conceive of as possibly false even though it appears to him to be perfectly adequately justified. And then he realises that, even though he has resolved to treat as false his old belief that he has senses and a body, that indeed he is identical with the person René Descartes, the inventor of analytical geometry, etc., he nonetheless must still exist. He cannot treat the belief he would express in the sentence, “I am, I exist” as false. After all, to have decided that one shall treat one’s beliefs in the existence of the world and everything associated with it, presupposes that one exists as thus deciding. As Descartes puts it, “I certainly did exist, if I convinced myself of something,” (p.24) namely, of the potential falsity of all his old empirical and mathematical beliefs. If there really is a supremely powerful and cunning deceiver who is deceiving him, then he himself has to exist, at least as someone or something which is being deceived. And so Descartes concludes, whether this supremely powerful deceiver should exist or not, at least that being who would be deceived, namely, he himself, must exist:³

Therefore, it is indubitable that I … exist, if he deceives me. And let him deceive me as much as he wishes, he will still never bring it about that I am nothing [i.e., that I do not exist] as long as I think I am something [i.e., that I exist]. Thus, having weighed up everything adequately, it must finally be stated that this proposition ‘I am, I exist’ is necessarily true whenever it is stated by me or conceived in my mind. (p.24)

Now in the earlier work The Discourse on Method of 1637, Descartes had put this point in a slightly different way. We may represent the way he puts things there as follows:

1. Whether or not I am the victim of massive deception, I must nonetheless be having thoughts (cogitationes)—either deceptive thoughts induced in me by a cunning deceiver or thoughts truly reflective of how things are beyond my mind. So either way I am thinking.

2. But if I am thinking, then there is something doing the thinking, namely, me. In other words, if I am thinking, then I exist.

Therefore, I exist. Cogito, ergo sum.

Evidently, in this earlier work, Descartes seems to be trying to derive the fact of his existence from the fact of his having thoughts (cogitationes), i.e., from the fact of his thinking. He seems to be inferring the proposition ‘I am’ from the proposition ‘I think’ by appeal to the general principle that if I think, then I am, I exist. And there are at least two things wrong with the idea that an inference along these lines is involved here.⁴ Firstly, it misrepresents the nature of the certainty with which Descartes knows that he exists. Secondly, it prevents one from seeing the nature of the certainty with which Descartes knows that he is thinking.⁵

Understanding why and in what sense Descartes knows, “I am, I exist,” is true whenever, as he puts it, it is stated by him or conceived in his mind is actually rather difficult. Admittedly, at first sight, it looks easy: one has to exist in order to reflect on one’s old beliefs in order to determine which might be false even though one has, by all ordinary standards, the best possible grounds. Similarly, one has to exist in order to be the victim of a supremely powerful, cunning deceiver. Evidently, this is a very simple argument whose basic principle is not much different from the idea that cogito, ergo sum is an inference in which the fact of Descartes’ existence is derived from the fact of his thinking. And what Descartes says on p.24 can look as if this is what and how he is arguing.

But appearances are deceiving. There is in effect a muddle implicit in this simple way of reading Descartes. We have to distinguish the procedure by which Descartes discovers “something … about which there is not even the slightest opportunity for doubting” (p.23) from what justifies this something as true in such a way that there is no possibility of doubting its truth. There is a straightforward reason for this: the process whereby Descartes discovers that a certain belief is dubitable is precisely that: a process of showing that the belief in question is dubitable in the sense that he can regard himself as having all the usual good reasons for having the belief and yet the belief might still be false. So in principle this procedure will not tell him why anything which survives the process survives it. In fact, when Descartes realises that the fact of his reflecting on his old empirical and mathematical beliefs entails that he exists; or again, when Descartes realises that even if he is being deceived, the very fact that he is being deceived entails that he exists: he is merely discovering or identifying a proposition which he cannot coherently doubt. He is not explaining why this proposition cannot be doubted. In other words, he is not explaining why what is discovered is true in such a way that its truth cannot be doubted.

In order to see why the proposition “I am, I exist” is necessarily true whenever he thinks it, we have to understand something of the way sentences in the first person work. The expression ‘I’ is a pronoun. This means that any sentence containing it does not express a truth or, for that matter, a falsehood in any stand-alone fashion, simply on its own. The sentence “I speak German,” expresses a truth or a falsity only as applied to someone, precisely its speaker, in this case, me. When I utter the sentence “I speak German” with a view to making a claim about myself, I express a truth because as a matter of fact I do speak German. But perhaps you do not, so if you were to utter this sentence with a view to making a claim about yourself, then it would not express a truth but a falsity. But either way it must apply to someone before it expresses something capable of being true or false at all, i.e., a ‘thought’ or proposition. In general, sentences involving the first person pronoun ‘I’ only express truths or falsehoods insofar as they apply to someone.⁶ So before any sentence involving the first person pronoun ‘I’ even so much as expresses a thought or proposition, i.e., something which is either true or false, there must be someone to whom the pronoun is applied, someone relative to whom what would otherwise be an empty form of words expresses a thought or proposition in the first place. In other words, a sentence involving the first person pronoun only expresses a truth or a falsehood if there is someone to whom the pronoun is applied.⁷ Given that there is someone to whom the pronoun applies, whether the sentence expresses thought or proposition which is true will of course be determined by what the sentence says (predicates) of this person and by what properties and relations this person possesses.

Now Descartes’ whole argument and thought-experiment must be expressed in the first person. In other words, it must essentially involve first person pronouns like ‘I’, ‘me’, ‘my’, etc. For if the argument and thought-experiment involved names like “Descartes” and descriptions like “the man who invented analytical geometry,” this would presuppose that he knew that he was Descartes or the man who invented analytical geometry. But all these beliefs have been suspended. So, just prior to asserting, “I am, I exist,” Descartes can only describe his situation in the following first person terms: “Either there is a supremely powerful and cunning deceiving who is inducing global error in me or there is not.” More simply put, he can only describe his situation in the following first person terms: “Either I am being radically deceived or I am not.” And these descriptions are not just empty words for him. He really does understand what these sentences say, i.e., grasp the thoughts these sentences express. But this is possible only if there is someone or something of whom these descriptions are true, to whom the first person pronouns do or at least could be applied. So Descartes can only understand these sentences, that is, grasp the thought or proposition they express, insofar as what is referred to in them by means of the first person pronoun exists.

At this point, the distinctive indubitability of what Descartes knows becomes more evident. What he knows is the proposition, “I am, I exist”, every time he states it or conceives it in his mind, i.e., every time he explicitly understands or consciously grasps the thought or proposition expressed by the sentence, “I am, I exist”. Such explicit understanding or conscious grasping is precisely what Descartes is getting when he speaks of the proposition, “I am, I exist,” being stated by him or conceived in his mind. But the truth of this thought or proposition is presupposed by every first person thought, that is, every thought which has to be expressed by a sentence involving first person pronouns, e.g., “I speak German,” “I am tired,” etc. But this thought is and must be itself a first person thought since Descartes may not understand by himself, that is, the entity referred to by the first person pronoun ‘I’, as the man René Descartes, the inventor of analytical geometry, etc. These beliefs have been suspended and yet the thought “I am, I exist,” still remains available for him. But because it is itself a first person thought, the thought “I am, I exist” has its own truth as a presupposition of Descartes’ simply understanding it! In other words, for Descartes to understand the thought expressed by the form of words, “I am, I exist,” is for him to recognise that the thought is true! This is why it is true in a fashion which makes doubting it impossible. For to understand it is at the same time to realise that it is true! Understanding it suffices for knowing it to be true! Just this is what Descartes is getting at when he says, “(T)his proposition ‘I am, I exist’ is necessarily true whenever it is stated by me or conceived in my mind.” (p.24) It is also what he is getting at when he says, a little earlier, that the deceiver “will … never bring it about that I am nothing [i.e., that I do not exist] as long as I think I am something [that I exist].” (p.24) One might put the point this way: the thought Descartes grasps when he thinks, “I am, I exist,” is self-certifying or self-guaranteeing, in the sense that to understand it is to see that it is true.

Importantly, the second thing which Descartes finds no opportunity to doubt is also self-certifying or self-guaranteeing, albeit in a slightly different way. This is his status as thinking. In fact, understanding what makes this status indubitable is, I think, the key to understanding why Descartes came to reject the famous line, cogito, ergo sum. As we have seen, the very form of this sentence, in particular, the fact that it contains the word ergo, i.e., ‘therefore’, suggests an inference: the premise is the claim that I think, the conclusion the claim that I am and what gets one from premise to conclusion is the principle “If I think, then I am, I exist.” Now this general principle says nothing about the truth or falsity of the proposition which forms its antecedent, i.e., the proposition expressed by the sentence ‘I think’. The question would therefore still remain whether this antecedent was true or not. So by suggesting an inference the famous line cogito, ergo sum falsely suggests that Descartes would also have to find out, in an independent act of inquiry, whether he was in fact thinking, which bit of knowledge he could then feed into the general principle as a premise. But the idea that one must first independently verify the proposition ‘I think’ obscures the distinctive way Descartes knows it to be true, a way which ensures that it is indubitable whereas the superficially similar proposition ‘I walk’ is not.

What I am getting at here can best be seen by considering the claim “I walk, therefore I am” (ambulo, ergo sum⁸). Obviously, any inference from ‘I walk’ to ‘I am’ depends upon the general principle “If I walk, then I exist”. This principle, too, like the principle “If I think, then I exist,” does not say anything about the truth or falsity of its antecedent, the proposition, namely, ‘I walk’. Insofar, then, as ambulo, ergo sum is understood as an inference in any standard sense, then the truth or falsity of the proposition ‘I walk’ must be established separately, in an independent or further act of inquiry. Consider now the proposition ‘I walk’ or, better, ‘I am walking now.’ In my mouth it is true, in yours false, because I am now walking about while you are sitting; to this extent, we have discovered no possible difference between the proposition ‘I walk’ and the proposition ‘I think’. But there is a difference between these two propositions: the truth of the proposition ‘I walk’ is a straightforwardly empirical matter. Why? Because my asserting this proposition obviously does not entail that I am walking now. I could have uttered the proposition, “I am walking now” while sitting—in which case I would have said something false.⁹ Things are, however, different with the proposition ‘I am thinking now’. If I am asserting anything, then, in some sufficiently wide sense of the term, I am thinking something. After all, assertion is a quite deliberate, thinking affair. So if I am asserting something, then I am thinking. So if the proposition I am asserting just happens to be “I am thinking,” then the very act of asserting and/or thinking it makes the proposition true.

Here we begin to see a distinctive way in which Descartes’ knowledge-claim that he is thinking is certain, such that he simply cannot deny it, nor be tricked into denying it by a supremely powerful deceiver: because the act of thinking to oneself, “I am thinking” involves use of the first person and because use of the first person involves thinking, the act of thinking to oneself, “I am thinking” makes itself true. Consequently, it is absurd in the sense of being self-defeating or self-undermining to try to deny it. If I think to myself “Right now, even as I think this very proposition about myself, I am not thinking,” I am performing an act which is curiously self-refuting, since the very fact of my performing this act entails the untruth of the proposition thought in the act. This, then, is the basis for Descartes’ certainty that he is thinking: the very act of pondering whether he is thinking entails a positive answer to the question, while the very act of pondering whether he is not thinking entails a negative one.

In summary: in the Meditations, unlike the earlier Discourse, Descartes proceeds first to establish the certainty of the claim that he exists and only then, somewhat separately, the claim that he is thinking. This is because in the Meditations, Descartes recognises that both his knowledge of himself as existing and his knowledge of himself as thinking are completely non-derivative and non-inferential; in particular, his knowledge that he exists is not derived, deduced or inferred from his knowledge that he is thinking.¹⁰

What this all comes to is that the very ability to grasp oneself as an ‘I’, that is, to be a self-conscious self, an entity capable of referring to itself in the first person, entails the beliefs that one exists and that one thinks. These are convictions built so to speak ineliminably into the structure and fabric of first-person awareness. The point of the famous line cogito, ergo sum is thus not really to provide an inference but to drive home the character of awareness of self as existing and as thinking (having cogitations in Descartes’ wide sense of the term) is absolutely original and non-derivative. This awareness of self constitutes a primal awareness built into all the more substantive, more empirical forms of self-consciousness which Descartes had previously considered and suspended, e.g., “I am René Descartes,” “I have just invented analytical geometry,” “I have a body,” “There is a pain in my foot,” and so on. This primal awareness of self as existing (sum) and as thinking (cogito) is implicit in his awareness that he is a rational animal, that he has a material body, and in particular, that he is René Descartes, and as such born in such and such year, currently sitting at such and such a time in such and such a room, wearing such and such a dressing gown, etc.

Descartes’ explicit recognition of distinctively rational beings as essentially having this primal awareness of self as existing and thinking is the first and most central aspect of what, as I said in the first lecture, makes Descartes the father of modern Western philosophy. For a concern to explore the nature and the implications of this primal awareness runs like a thread through much Western philosophy since Descartes. Perhaps the most systematic and determined attempt to explore the nature of this awareness and its implications comes with Immanuel Kant (1724-1804) and those philosophers directly influenced by him, viz., Johann Gottlieb Fichte (1762-1814), Friedrich W. Schelling (1775-1854) and Georg W. F. Hegel (1770-1831). Many later thinkers, in particular, those in the so-called continental tradition, e.g., Edmund Husserl (1859-1938), Martin Heidegger (1889-1976) and Jean-Paul Sartre (1905-1980) have been similarly fascinated by this primal awareness of self.

§ 2: That Mind is better known than Body

Having discovered this primal awareness of self (“I am, I exist, whenever I conceive it clearly in the mind”), Descartes now goes on to explore it some more. “(W)hat, then, am I?,” he asks and answers as follows:

A thinking thing. And what is that? A thing which doubts, understands, affirms, denies, wills, does not will, which also imagines and senses. That is obviously a fair number of things, if they all apply to me. (p.26)

Evidently, Descartes wants now to go on to spell out a little more what thinking is. Species or kinds of thinking include doubting, understanding, affirming and deny. Descartes also lists willing and not willing, i.e., acts of deciding to do such and such and refusing to do such and such. Notice, however, that in this list he also includes imagining and sensing, by which latter Descartes means perceiving. He then observes that these are quite a few things—“if they all apply to me”. The qualification “if they apply to me” indicates that while Descartes might be initially tempted to regard all these things as species or kinds of thinking, he in fact believes there to be reasons for restricting the list a little. Not all of the things on this initial list are truly or unequivocally forms of thinking.

The targets here are imagining and sensing, i.e., perceiving. Descartes writes,

(T)he fact that it is I who doubt, who understand, who will, is so obvious that there is nothing which could make it more evident. In fact, I am also identical with the ‘I’ who imagines because even if it happened, as I supposed, that none of the things I imagined were any longer true, the power of imagining itself truly exists and is part of my thought. Thus I am the same subject who senses, or who notices physical things as if through the senses; for example, I now see light, hear sound and feel heat. Those are false, because I am asleep. But I certainly seem to see, to hear and to get warm. This cannot be false. This is what is meant, strictly speaking, by my having a sensation and, understood precisely in this way, it is nothing other than thinking. (pp. 26-27; translation corrected)

It is easy enough to regard doubting, understanding, willing and the like as species or kinds of thinking in that sense of the term ‘thinking’ which permits Descartes to be thinking even if he is under a massive illusion such that none of the objects he is thinking about actually exist. But it is not so easy with regard to perceiving and Descartes knows this. If I see something, we usually think that there is something that I see. If, for example, someone sees an apple tree standing there in the garden, we typically regard ourselves as entitled to infer from this fact that there is an apple tree standing there in the garden.

So Descartes needs to make his talk of sensing, perceiving and experiencing, of sensations, perceptions and experiences, more precise. He needs to find the right way of describing those items in his mind which he has thus far indiscriminately called sensings, perceivings and experiencings, of which he has certain knowledge that they are in his mind. They must be describable by and knowable to him in a way which does not entail that there actually is something sensed, perceived or experienced. He must be able to have these items in his mind, as items of whose existence and nature he can be aware, even if there is no object sensed, perceived or experienced. And so Descartes says, as we have just seen, that, strictly speaking, what he is indubitably aware of as occurring in his mind are not seeings, hearings, touchings, tastings and smellings, but seemings-to-see, seemings-to-hear, seemings-to-touch, seemings-to-taste and seemings-to-smell. What we really mean by a sensation, a perception or an experience is in fact a seeming-to-see or –hear or –touch or –taste or –smell. And since these can, according to Descartes, occur in his mind without there actually being anything seen, heard, touched, tasted or smelt, he can now regard them as species of thinking in that sense of the term ‘thinking’ which is available to him when he has withheld assent from all the things an evil spirit could trick him into believing.

Furthermore, the presence of such seemings-to-sense in his mind is certain in just the same way as his existence as undergoing them is. After all, just as in any deception there must be someone who is deceived, so, too, there must be that with regard to which someone is deceived. In this case, the fact with regard to which Descartes imagines himself to be deceived is that certain seemings-to-sense (to see, to hear, to touch, to taste or to smell) are what they seem to be, namely, real sense-experiences or perceivings, as opposed to dream sense experiences or dream perceivings, or those seemings-to-sense or –perceive which one has as a victim of the evil spirit.

So now Descartes can draw a crucial conclusion, a conclusion which motivates the title of the whole Second Meditation, namely, that the mind is better known than the body (whether one’s own body or those other bodies with which one stands, as a human being, in causal interaction). When the contents of his mind are understood consist either in doubting, understanding, judging or willing, or again, in seemings-to-sense (seemings-to-perceive), these contents are as indubitably and certainly known as his existence precisely as thinking in any of these ways. Initially, it seemed to Descartes that he were better acquainted with empirical objects in the empirical world. But now it appears that this is not so: properly understood, one knows the contents of one’s own mind, i.e., the thoughts in it, better than the real-world objects thought about in such thoughts. That he is having such and such a thought is something the evil spirit cannot deceive him about because the evil spirit’s deception consists precisely in getting him to accept as a genuinely veridical perceptual experience or a genuinely true belief such and such a thought, this one he is having now, about which he is simultaneously wondering whether it is a genuinely perceptual experience, a genuinely true belief, etc.

Many philosophers since Descartes have made much of this idea that we have indubitable acess to our own thoughts and experiences. Empiricist philosophers like John Locke (1632-1704), George Berkeley (1685-1753), David Hume (1711-1776) and their more modern descendants, e.g., Bertrand Russell (1872-1970), have developed this idea into the notion that our knowledge of the items occurring in our minds right now is (a) direct and immediate in our own cases in a way in which it is not for others; and (b) infallible. If you are undergoing such and such a perceptual experience, or have such and such a belief, or indeed are suffering from such and such a kind of pain, I can only know about these things indirectly, by understanding your linguistic utterances (when you utter the sentence, “What a wonderful oasis there is there on the horizon!”), or understanding your non-linguistic behaviour (when you writhe about the floor, clutching the side of your jaw, which provides me with evidence that you have a severe toothache). You, by contrast, know these things directly and immediately, without any inference. Furthermore, according to these philosophers, you simply cannot be wrong about this. Thus, if you believe that you have the belief that Tony Abbott is Prime Minister, then you really do have the belief. While your belief that Tony Abbott is PM is highly fallible, your belief that you believe that Tony Abbott is PM is said, at least by such philosophers, to be infallible.¹¹ Similarly, if you believe that you are actually enduring incredible pain, you are enduring incredible pain. Finally, if you believe that you are seeming to perceive an intruder lurking in the garden, you are actually seeming thus to perceive.

§ 3: That External Things are perceived only by the Mind—Descartes’ Lump of Wax

At this point in the Second Meditation (top of p.27) Descartes seems to take a rather surprising, even irrelevant tack. First he repeats a point he has already made, namely, that initially external physical things seem to him to be better known than things in and of the mind: “(I)t still seems to me—and I cannot prevent myself from thinking—that physical things, the images of which are formed in my thought and which the senses themselves explore, are much more distinctly known than the unknown me who is outside the scope of the imagination, although it really is surprising that I understand more distinctly things which I realize are doubtful, unknown and foreign to me than what is true, what is known and, ultimately, what is myself.” (p.27) He then uses this claim as a way of introducing an issue whose connection with what has gone immediately beforehand is not obvious: the issue of how, in virtue of what, we know external things. It is important to note that this is indeed a different question to the one which has stood centre-stage thus far, namely, whether the knowledge-claims Descartes has previously made about empirical and mathematical matters really do count as knowledge. For this new question concerns the issue of what knowledge of external things would consist in. In other words, it concerns what such knowledge would involve, irrespective of whether we have it or not. In particular, Descartes focuses, as we now shall see, upon a central dimension of this new question, namely, how the mind and the senses relate to one another in the production of whatever knowledge of the external world we do in fact or might have.

But why, one will ask, should Descartes want to raise this issue here. I think, however, he has a crucial polemical reason for this, that is to say, a reason which has nothing to do with the ostensible project of refuting scepticism and providing human knowledge in general with firm foundations one and everything to do with demonstrating that Galilean rather than an Aristotelian or Scholastic approach to natural inquiry yields true knowledge of external things. There are two aspects to this demonstration, the one a quite general claim, the other a relatively specific which is particularly congenial to the thesis that Galilean natural philosophy accords better with how the mind and the senses actually cooperate to engender knowledge of nature.

Firstly and primarily, Descartes wants to demonstrate the general claim that when we truly understand how the mind and the senses relate to one another in the production of knowledge of the external world, we see that the senses, i.e., perceptual experience, is very much the hand maiden of the intellect. In itself, perceptual experience does not really yield systematic theoretical knowledge at all. Rather, it merely provides us with evidence for how the world really is, evidence which the purely conceptual, non-sensual intellect (mind) has to process in order to arrive at theoretical knowledge of the world. If, however, this is so, then we arrive at a conception of the intellect and of perception according to which intellect does not depend essentially on perception. In other words, while as a matter of fact there occur in Descartes’ mind what Descartes calls sensations “strictly speaking” (top of p.27), i.e., seemings-to-see, -to-hear, -to-touch, -to-taste, and -to-smell, there need not occur such things; it is perfectly coherent and possible that such ‘sensations’ should not be present in the mind at all. In other words, it is possible that he might have a purely intellectual mind, i.e., one which contains no sensations, no perceptual experiences and—since to imagine something x is to imagine what it would be like to have perceptual experience of x—also no imaginings, no mental images. And so Descartes will have shown that the link between being a mind and having a capacity for perceptual experience is contingent. He will have removed one possible reason for denying that a purely intellectual mind is possible. And so he will have made a least a small step towards showing that in principle he could exist as a purely thinking thing, that is, as at most a thinking thing.¹²

Secondly, Descartes wants at least to intimate the specific claim that when we truly understand how the mind and the senses relate to one another in the production of knowledge of the external world, we see that what the mind or intellect grasps is primarily quantitative. Evidently, if this is so, then Descartes will have shown that the very notion of what it is to know the external, natural world implies that such knowledge requires application of mathematical methods—precisely the kind of thing above all Galileo first employed systematically to engender highly abstract, idealised and unified descriptions of natural phenomena, e.g., the laws of motion in a straight line and, more specifically, the law of free fall in (what we today call) the Earth’s gravitational field.

Descartes seeks to demonstrate both the general and the specific claims by means of his famous example of the wax:

Consider those things that are commonly thought to be understood most distinctly, namely, the bodies which we touch and see—not bodies in general, because such general perceptions are usually inclined to be more confused—but single body in particular. For example, let us take this piece of wax. It has just been extracted from the honeycomb. It has not yet completely lost the taste of honey and it still retains some of the scent of the flowers from which it was collected; its colour, figure, size, are obvious. It is hard, cold, easy to touch and, if tapped with a finger, it emits a sound. Thus it has everything that seems to be required for a body to be known as distinctly as possible. But notice that, as I speak, its smell is lost, the colour changes, it loses its shape, increases in size, becomes a liquid, becomes hot and can barely be touched. Nor does it still emit a sound if tapped. But does the same wax not remain? It must be agreed that it does; no one thinks otherwise. (p.27)

We are evidently to imagine a lump of solid wax which Descartes is holding in his hand and bringing closer and closer to the fire. As it gets closer to the fire, it starts to melt and loses all the previously listed perceptible, sensuous properties (of taste, smell, colour, hardness, temperature and its perceptible specific shape). And yet it remains the same kind of thing, namely, wax, and indeed the same individual thing, namely, this lump of wax.

It seems, then, that Descartes is trying to make two interconnected points. Firstly, the wax example shows, according to Descartes, that the general kind ‘wax’ is not to be identified with or defined in terms of any set of sensible properties—as if one could say that x is a lump of wax if and only if x tastes of honey, smells of flowers, is white,¹³ is solid, is not hot to touch, emits a sound when tapped, etc. Secondly, the identity of this particular lump of way, this particular individual, as the particular individual it is, is not dependent on any such set of sensible properties—as if something could only be this lump of wax only if it tasted of honey, smelt of flowers, were yellow, solid, not hot to touch, emitted a sound when tapped, etc. Neither the identity of the kind of a perceptible thing nor the identity of the perceptible thing itself requires that it possess any such specific sensuous properties. So what it was that, as Descartes puts it, “was understood so distinctly” (bottom of p.27) that we had no difficulty or uncertainty asserting that, even when molten, Descartes’ lump of wax remains wax and the same individual lump it was originally?

Certainly none of those things that I reached through the senses, for whatever fell within the scope of taste, smell, sight, touch or hearing has already changed. The wax remains. (pp.27-28)

That is, the wax is not to be identified with any set of perceptible sensuous properties.

Was it perhaps what I now think, namely, that the wax itself was not really that sweetness of honey, nor the fragrance of flowers, nor that whiteness, shape or sound, but the body, which a short time ago presented itself to me with those modes and which now appears with different modes? But what exactly is this thing that I imagine? (p.28)

In other words, is it the case that, even at the pre-philosophical level of ordinary everyday speech (for such pre-philosophical ‘intuition’ is what Descartes is appealing to now), what makes the wax wax, indeed this particular lump of wax, is a principle or rule of unity specifying a certain regular way of changing perceptible sensuous properties? But if this is the case, how are we to understand more adequately and explicitly the precise sense in which it is the case?

Let us pay attention and, having removed whatever does not belong to the wax, let us see what remains. It is nothing but something that is extended, flexible and changeable. But what do the words ‘flexible’ and ‘changeable’ mean? Is it what I imagine, namely, that this wax can change shape from being round to square or from square to triangular? Not at all. For I understand that it is capable of innumerable similar changes, even though I cannot review whatever is innumerable in my imagination and therefore this understanding does not result from the faculty of imagining. What is meant by ‘extended’? Is it not the case that even its very extension is unknown? For melting wax increases in volume, increases further when it boils and increases further again if the temperature rises further. Nor could I correctly judge what this wax is unless I thought it could assume many more variations in extension than I have ever grasped in my imagination. I have to concede, then, that I cannot in any way imagine what this wax is, but that I can perceive it only with my mind. I say this about a particular piece of wax; it is even clearer about wax in general. (p.28)

Descartes urges us to reflect a little more closely upon what we mean when we say that the identity of the wax is given by a certain regular way of changing, e.g., with regard to shape. Can we regard the identity of the wax as given by some finite sequence of possible changes, e.g., < round, square, triangular>, as if the identity of the wax were given by a whole collection of sequences which articulate the way it changes under certain specific conditions?

No, for constitutive of the identity of the wax is the capacity to undergo changes which are not and could not be listed in any finite number of finite sequences. The wax can change its shape and indeed all sorts of other properties in ways which no finite list of finite behavioural patterns can capture. According to Descartes, this shows something decisive: we do not understand the identity of the wax via the faculty of imagination; this identity is something purely conceptual, something entirely non-perceptible. We can obviously perceive a ordinary sensuous property such as a specific colour or a specific shape. And we can also perceive a finitely long sequence of changes in the specific sensuous properties of a thing, e.g., as we watch a certain liquid in a test tube change from green to yellow to red. But neither the identity of the kind wax nor the individual identity of this lump of wax is understood in this imaginative, hence potentially perceptible, way. Rather, it is grasped by the intellect or mind, which picks up on the completely non-perceptible, non-sensuous and, to this extent, ‘hidden’ properties and relations of things—whereby the perceptible, sensuous properties of the wax serve merely as indicators, as symptoms of or evidence for, that which makes the wax both wax in general and this individual lump of wax.

Nonetheless, there is something right, Descartes believes, in the idea that the identity of the wax, both in general and as an individual, lies in a certain principle or rule of change in the wax’s perceptible, sensuous properties. For now Descartes asks again, “What, then, is this wax that can only be perceived by the mind?” (p.28) And he answers,

It is the same wax that I see, touch, imagine, and finally the same wax that I thought was there from the beginning. But what should be noticed is that perceiving it is not a case of seeing, touching or imagining, nor was it ever such although it seemed that way earlier, but it is an inspection of the mind alone, which may be either imperfect and confused as it was earlier, or clear and distinct as it is now, depending on whether I pay more or less attention to what it is composed of. (p.28)

This is a crucial, albeit obscure passage. Descartes first points out that whatever the identity of the wax is, it is something which the mind accesses through diverse senses, in particular, through sight and touch: Descartes sees that the wax has such and such a shape and such and such a degree of hardness and he can learn these things through touch as well. It is, after all, perfectly possible to learn that something is, say, square or hard either by inspecting it visually or by inspecting is tactilely.¹⁴ So according to Descartes even for everyday pre-philosophical and pre-scientific discourse what the wax is, both in general and as an individual, is something accessible across diverse modes of perceptual experience. Furthermore, he goes on in the final sentence to intimate, surely rightly, that at least in many cases—and wax is one of them—what a thing is is determined by what it is composed of.

With this Descartes is implying—he is certainly not stating it explicitly—that the identity of the wax lies in the rule or principle according to which, not its perceptible sensuous properties change, but the way its inner constitution changes across time: the way its constituents are arranged and distributed in space. So in addition to arguing for the general claim that what the wax is, both in general and as an individual, is something not directly perceptible, but something grasped by the mind, indeed something to which the mind infers in acts of judgement,¹⁵ Descartes is also at least insinuating that this identity is to be understood as a certain lawful pattern of change in the way the matter out of which the wax is composed is arranged. In other words, he is insinuating his favoured view of what physical things are, namely, spatial deployments of corpuscles, which are qualitatively identical components¹⁶ of all physical things, whereby what makes the perceptible surface properties of physical things differ from one kind of thing to another is merely the way these qualitatively identical components are arranged. Notice, of course, that if the lawful pattern of change which defines the wax both to be wax in general and to be this particular bit of wax is conceived in these microstructural terms, then the identity of things, even already for ordinary, everyday pre-philosophical and pre-scientific discourse, is quantitatively specifiable: ultimately, saying what things are boils down to determining the at least in part mathematically specifiable laws according to which their imperceptible micro-constituents interact with one another and the rest of the world.

© Carleton B. Christensen, 2008, 2010, 2011, 2012, 2013 and 2104