Descartes’ Metaphysics of Nature and Mind—The Sixth Meditation (Part I)

In the sixth and final of his Meditations on First Philosophy, Descartes explicitly introduces his metaphysics of the human mind and the empirical world, i.e., nature, in which the human mind exists. Crucially, this metaphysics of mind and nature has been tacitly guiding Descartes’ reflections throughout the preceding five Meditations. That, however, this is so only really becomes clear in this final Meditation. For here, as we shall see, Descartes implicitly explains why he has made the crucial assumption of the argument from dreaming and thus, by extension, of the argument about the possibility of global deception through a supremely powerful, malevolent mind. This assumption is that even if he were dreaming, even if he were the victim of an all-powerful, deceiving evil mind, he would still exist as genuinely thinking and not merely as dreaming in his bed or hallucinating in, say, the vat into which the information-technologically savvy evil mind has placed his brain after removing it from his skull. In other words, even if he were in any such condition, he would genuinely exist as having thoughts (in Descartes’ wide sense of the term, of course) passing through in his mind, available for him to think about, i.e., to withhold assent from, to doubt, to question, to ponder the veracity of, and also, as with his idea of God, to explore the content or meaning of.

§ 1: The Existence of Material Things and the Critique of Imagination

At the beginning of the Sixth Meditation Descartes states that because he knows with certainty that God exists, he knows with certainty that physical things “are at least capable of existing insofar as they are the object of pure mathematics, because I perceive them clearly and distinctly.” (p.57¹) In other words, because he has established the existence of God, he knows that his mathematical reasoning cannot be radically deceptive in the manner he had, in the thought-experiment of the evil mind, previously speculated to be possible. But, he says, “I still have to consider whether material things exist.” (p.57)

On the face of it, this latter claim is puzzling. Surely, one will say, in establishing the existence of God, Descartes has shown not merely that he can trust his mathematical reasoning; he must also equally have shown that he can trust the testimony of his senses. That is, in proving the existence of God, Descartes must surely have found reason just as much for re-asserting his original naïve faith in the senses as for re-asserting his original faith in his capacity to reason mathematically. Both species of claiming-rationally-to-know are equally dependent both on God’s existing and on Descartes’ knowing God to exist. So why should Descartes think that the existence of material things is a question not yet answered?

Notice that in the first few pages of the Sixth Meditation Descartes gives, a recapitulation of the course of his Meditations up to this point. This recapitulation extends from pp.57-63 and ends with explicit reference to the proof of God in the Third Meditation, followed by the conclusion, “Therefore, physical things exist.” (p.63) Now this is indeed a recapitulation. So Descartes reaches the conclusion that physical things exist on the basis of what he has accomplished previously, hence not in the Sixth Meditation itself. From this it follows that the Sixth Meditation cannot be really dedicated straightforwardly to answering the question of how he knows material things to exist, as if this were a conviction to which he were still not entitled. Rather, the Sixth Meditation is given over to, not to proving this conviction, but to spelling it out. In the Fifth Meditation he has elaborated the essence of physical or material things and now he wants to spell out what it means to say that they exist. That is, having spelt out, in the Fifth Meditation, the essence, that is to say, the concept, of an individual material thing, he now wants to spell out the essence of the totality in which they factually exist—the concept of external, empirical reality itself, or, alternatively put, of the empirical world or ‘nature’.

As always, there is a hidden agenda here: Descartes wants to spell this conviction out in order to reveal just how much better than those who rely on Aristotle he can account for our pre-philosophical conviction that external empirical reality is as we claim it to be on the basis of sense experience. For in the course of his recapitulation Descartes examines and rejects certain received ways in which pre-philosophical common sense and much traditional philosophy, based as it is on Aristotle, understand the nature of external empirical reality, that is to say, the concept of the empirical world, and the nature of the ideas and mental processes by which we attempt to know this external reality. He then introduces his preferred metaphysical account of the empirical world, of mind and of how the latter fits into the former. This, he thinks, yields a much better conception of all three—of the empirical world itself, i.e., of ‘nature’, of the mind, and in particular how these latter fit together. This conception is better not just in the sense that it is true, i.e., because it, unlike its older, Aristotle-based competitor, shows what nature and mind truly are. It is also better in another sense: it shows why both religious faith and theological inquiry are needed if it is to be at all possible truly to know the empirical world, that is to say, nature, the mind and in particular, how they relate to one another.

In short, the question as to what basis he has for his claim to know the existence of material things serves Descartes as a vehicle both for introducing his critique of commonsense and traditional philosophical views; and for transitioning to the view which Descartes regards as superior both epistemologically and theologically. Descartes already knows the basis upon which he is rationally entitled to assert that material things exist and that they by and large exist as what he perceives them to exist as. The point is now to show how they collectively exist, i.e., what that totality is which their existence constitutes, and in particular, how different conceptions of this totality, the older, Aristotle-based one and Descartes’ favoured Galilean conception, yield, respectively, inferior and superior accounts of our entitlement to claim to know empirical reality, i.e., the so-called external world—inferior and superior in both the epistemological and the theological sense, for Descartes will argue that these two senses of inferior and superior go hand in hand. One conception, the one to which commonsense naturally comes and to which traditional philosophy has in fact come, is inadequate because it is not truly certain, i.e., can give no real account of our entitlement to claim to know. The other conception, the one Descartes endorses, is not subject to this weakness. In short, in the opening pages of the Sixth Meditation, Descartes recapitulates the argument of the preceding five Meditations as a foil for contrasting different metaphysical conceptions of nature, mind and their interrelation,² whereby the criteria for their evaluation are both epistemological and theological because these criteria are, as Descartes wants his argument to show, interconnected. In other words, under the guise of explicitly demonstrating what, strictly speaking, does not need now to be demonstrated, namely, that he is justified in believing that the ordinary, everyday material things of this world exist, Descartes plays off traditional and commonsensical notions of mind and nature against the more modern ones he endorses.

This means that by the time he has reached his Sixth Meditation, Descartes is only using the question of whether physical or material things individually exist as a foil around which to organise a transition from inadequate to adequate conceptions of what the totality of physical or material things really is and how his mind relates to and occurs within it. The epistemological issue of how to eliminate the possibility of global deception and restore one’s original, naïve faith in the capacity for making truly rational empirical and mathematical knowledge claims is shown to have its answer in the issue of the ontological and indeed metaphysical framework³ which, or so Descartes believes, yields a nicely Christian conception of how the mind relates cognitively and practically to the world. Needless to say, this is also a decidedly Galilean and anti-Aristotelian conception of the mind and indeed of nature itself. So the short recapitulation with which the Sixth Meditation begins is Descartes’ deliberate attempt to demarcate the path from theoretically inadequate and indeed Aristotelian, hence pagan conceptions of mind, soul and nature to theoretically more adequate and indeed truly Christian ones. That this is so is confirmed indirectly by Descartes himself. In a letter of January 28^th^, 1641, to his friend and colleague, the monk and scientist Marin Mersenne (1588-1648), he writes that what he wanted people mainly to notice in the Meditations are his proofs of the nature of mind, the existence of God, the immortality of the soul and the (mathematical!) essence of material things. He then goes on to say,

But I think I included many other things besides; and I will tell you, between ourselves, that these six Meditations contain all the foundations of my Physics.⁴ But please don’t say so; because those who favour Aristotle would perhaps make more difficulty about approving them; and I hope those who read them will accustom themselves insensibly to my principles, and recognize their truth, before noticing that they destroy those of Aristotle.⁵

Here Descartes explicitly says that in the Meditations he is proceeding surreptitiously, that is, is pursuing a hidden agenda!

The fact that Descartes is pursuing a hidden agenda along the lines I have argued for throughout these lectures indicates, of course, that the old views which Descartes recapitulates here are not necessarily ones Descartes himself had held as a matter of brute biographic fact. In fact, whether at any point Descartes himself really ever did hold these views is irrelevant. For in fact Descartes is giving, in fictionally autobiographic form, an account of views representative of the traditions and habits of thought he wants to overcome, views which, when subject to sufficiently sustained critical reflection, must inevitably pass over into the views Descartes now does indeed hold: precisely a Galilean metaphysics of mind and nature.

This objective explains why Descartes first turns to consider the nature of imagination and in particular to distinguish it from what he calls the understanding. By the faculty of the imagination Descartes understands a faculty for having and wielding images, as in geometrical reasoning. Importantly, this conception of imagination does not necessarily imply fantasy or day-dreaming, i.e., the invention of images known to the inventor to be fictitious or fanciful. By the understanding Descartes also means a faculty or capacity of the mind, namely, its faculty of, or capacity for, discursive reasoning: the asserting of propositions or, if you prefer, sentences, and reasoning from them as premises in inferences or reasoning to them as the conclusions of inferences. Very crudely, we might describe imagination as an aesthetic faculty for imaging, picturing or, mutatis mutandis, even mimicking things whereas understanding we may describe as a discursive faculty for wielding symbols. There is, of course, a connection between imagining and perceiving: to imagine something x in the sense of forming a picture of x in one’s mind is typically a matter of imagining what it would be like for one to perceive x from such and such a position, in such and such an orientation, under such and such conditions, etc. By contrast, understanding is a sensually colourless affair; it does not of itself involve anything more than so to speak words passing through one’s mind in inner dialogue with oneself.

Now it is a feature, or so Descartes assumes, of older, Scholastic doctrines of mind and reason that they were not able adequately to distinguish imagination from the understanding. In consequence, such doctrines provided no genuinely effective rules for guiding the intellect, that is to say, no genuinely effective method for comprehending empirical and indeed mathematical reality. Descartes begins his effort to distinguish clearly between imagination and understanding by considering the nature of the former. He says that

if one considers very carefully what the imagination is, it seems to be nothing but a certain application of the cognitive faculty to a body that is intimately present to that faculty and that therefore exists.

To clarify that, I will first consider the difference between imagination and pure understanding. When I imagine a triangle, for example, I do not merely understand that it is a figure bounded by three lines but, at the same time, I also see those three lines with my mind’s eye as if they were present, and that is what I call imagining. However, if I wish to think about a chiliagon, I understand equally well that it is a figure that consists of one thousand sides, just as I understand that a triangle is a figure that consists of three sides, but I cannot imagine a thousand sides in the same way, that is, I cannot see them as if they were present. Even if I represent to myself some very confused figure on that occasion, because of my habit of always imagining something whenever I think of a physical thing, it is clear nevertheless that it is not a chiliagon, because it is not in any way different from what I would also represent to myself if I were to think about a myriagon or any other figure with many sides, and it is useless for knowing the properties by which a chiliagon differs from other polygons. However, if we were discussing a pentagonal I could understand its shape too, just like that of a chiliagon, without the aid of the imagination. But by applying my mind’s eye simultaneously to its five sides and to the area they enclose, I am also able to imagine it. I notice clearly in this example that, in order to imagine, I need a characteristic effort of the mind that I do not use in order to understand. This new effort of the mind shows clearly the difference between the imagination and pure understanding. (pp.57-58)

Clearly, Descartes is at the very least concerned to distinguish between two cognitive faculties or capacities which he sees as in danger of being confused with one another, namely, imagination and understanding. It soon becomes clear, however, that he has distinguished between imagining and understanding in order then to argue that the latter is separable from the former, i.e., one can have understanding without imagination:

I also think that the power of imagining which I have, insofar as it differs from the power of understanding, is not required for my essence, that is, for the essence of my mind because, even if I did not have it, I would undoubtedly remain who I am now. (p.58)

According to Descartes, understanding understood as he understands it can stand alone. A purely discursive mind, which merely reasons, which neither imagines nor indeed perceives, is perfectly possible.⁶

Given, however, that imagination and understanding are not just distinguishable but genuinely separable faculties or capacities, Descartes can now use this point to draw some further conclusions:

It seems to follow that the imagination depends on something that is distinct from me. I understand easily that, if some body existed to which my mind were so united that it could apply itself to it at will as if it were inspecting it, it would be possible to imagine things through that physical body. Thus this way of thinking differs from pure understanding only in the sense that the mind, when it understands, turns back on itself in some way and reflects on one of the ideas that are inside itself; however, when it imagines, it turns towards a body⁷ and sees something in it that resembles the idea that had been understood by itself or perceived by sensation. I can easily understand, I say, that the imagination can take place in that way if such a body exists [i.e., if such a body is, and is genuinely known by me, to exist]. Since no other equally satisfactory way of explaining it occurs to me, I hypothesize that such a body probably exists. (p.58)

In other words, if imagination is a faculty not just distinguishable but separable from understanding, then one can account for it as follows: whereas understanding is simply discursive reasoning with the ideas caused in one’s mind by things outside, imagination is a matter of noting the structural similarities, the isomorphisms or, as Descartes terms it, the resemblances, between the ideas in one’s mind and items one is perceiving or has perceiving and which these ideas are about. This isomorphism or resemblance must be due to the way the object of one’s idea is made up. In other words, the idea has a certain structure which corresponds one-to-one to those properties of the object of the idea which are causally responsible for the idea’s occurring in one’s mind. There is, or so Descartes reasons, no other way of explaining imagination except as the noting and exploiting of a one-to-one isomorphism between the idea in the mind and the object of the idea, which isomorphism is due to the causal relation between the idea and its object. So the faculty of, or capacity for, imagination as Descartes understands it implicates a causal relation of an idea in one’s mind to something, in particular, to the object of this idea. If, however, this is so, then Descartes has an account of how we know there to be external things beyond our minds, in particular, those external things which constitute the objects of the ideas in our minds.

Having got this far, however, Descartes now makes the following criticism: precisely because his attempt to ground his belief in the existence of material things by appeal to the distinctive character of imagination permits him only to hypothesise that the object of his idea really exists, “it exists only probably and, despite my careful examination, I still do not see how, from the distinct idea of a physical nature which I find in my imagination, I can derive an argument that concludes necessarily that some body exists.” (p.58) So now Descartes rejects everything he has said thus far; he rejects the account he has just given of how he comes to his naive, pre-philosophical conviction that external objects exist more or less as he perceives and thinks they do. After all this discussion, Descartes ultimately declares to be unsatisfactory (because it yields a merely hypothetical, probabilistic rather than absolute certainty) the attempt to justify belief in the external world by appeal to the character of imagination as picturings of the objects of his idea which stand in causal relation to precisely these objects. So why has Descartes ever bothered with this account?

We must remember that at the beginning of the Sixth Meditation Descartes claims to be recapitulating how he came to his old views before he ever embarked on his Meditations. More accurately, since the Meditations are not really autobiographical but merely fictionally so, Descartes is recapitulating traditional, Aristotle-inspired views of the mind and how we know the existence of external things. In particular, in his account of imagination Descartes is presenting characteristically Scholastic notions of ideas, of the way ideas have content or meaning and of the nature of thinking itself. And he is characterising these ideas as if they were ideas he had once endorsed which he has now come to realise to be incapable of providing the resources needed for explicating and explaining belief in the external world. Descartes’ insistence on the need to distinguish imagination and the understanding from one another derives from his conviction that a tendency to conflate the two faculties or capacities is inherent to pre-modern, Scholastic accounts of the mind and mental process. In the Middle Ages there certainly was a tendency to explicate or interpret the character of ideas as being about something, as having a certain content or meaning, by appeal to the notion of picturing. Our ideas were seen as representing reality in a manner analogous to the way in which pictures represent things. Thus, crucial to this view is the idea that what makes an idea in the mind an idea about A rather than an idea about B is its character as in some sense resembling A rather than B.

Already in the Third Meditation Descartes has shown himself to be hostile to the view that the character of an idea as about A rather than B can explicated as a matter of the idea’s resembling A rather than B: even if his ideas “originated from things that are distinct from me, it does not follow that they must resemble them.” (p.34) And he wants to reject this view not, or not just, because it is an inadequate account of what ideas are and how they represent reality. Descartes wants to reject the view because it insinuates a false picture of how reality itself is. For it leads one to regard as literally out there in the world things which, on the view of empirical reality which Descartes recommends, are either not there at all or at least only there in a fashion which only science and the mind rather than everyday opinion and the senses can identify. Needless to say, the view of empirical reality which Descartes recommends is, as he thinks, the one implicit in Galilean natural philosophy. And this view of empirical reality, this metaphysics of nature, teaches that the true nature of empirical things consists in their character as spatial arrangements of invisible corpuscles. As Descartes sees things, all material things are material in the sense of being made up out of fundamental, indivisible and qualitatively identical corpuscles or atoms; the various differences in colour, sound, taste, smell, hardness, heaviness, etc. which we perceive through the senses are all ultimately due to differences in the spatial arrangement of these fundamental, indivisible and qualitatively identical corpuscles.

So on this metaphysical view of nature, it seems that the sensory qualities of things—precisely their colour, sound, taste, smell, hardness, heaviness, etc.—are not really in the things we perceive as having them. More accurately, insofar as colour, sound, taste, smell, hardness, heaviness and the like are genuinely objective, independent properties of material things, they are nothing more than certain types of spatial arrangement of fundamental particles. The strictly sensuous character of things as coloured, resonating, tasting, smelling or feeling in certain ways must therefore be understood as the subjective effect typically in creatures likes us by what the sensory qualities are, objectively speaking. In short, the view of nature Descartes recommends teaches that our ordinary perceptual concepts have an objective and a subjective side to them: what we mean by ‘red’ is a certain kind of introspectively available sensation caused in us by instances of a certain type of spatial arrangement of fundamental particles. The type of sensation constitutes redness in the subjective sense while the type of spatial arrangement of fundamental particles constitutes redness in the objective sense.

Unfortunately, if one interprets, as the Scholastic philosophers were wont to do, the character of ideas as being about something by appeal to the notion of picturing, one is fated not to see this. For if one regards ideas as pictures of reality, one will think that these ideas purport to represent the object in its formal reality and actuality as being exactly like the object in its intentional reality, that is, as it is presented in the idea. As a result, one will conflate the subjective and objective senses in which we speak of sensory qualities, thereby treating the sensual character of empirical things as a completely objective, causally efficacious feature of these things. In effect, one will project what are actually nothing but the effects had by external things on our minds outwards, as real features of these external things themselves. This is not only wrong, it also fundamentally hamstrings inquiry into nature. For it amounts to taking as the causes of the ideas in our mind what are in fact merely effects of these causes. And this has two interconnected deleterious consequences. Firstly, by conflating certain effects had upon the mind by external things with the various objective properties in virtue of which these things cause these effects, this Scholastic conception of ideas hinders development of a genuinely effective method for investigating nature, precisely the kind of method which would enable one to identify the truly objective, genuinely causal character of things, which consists in their being spatial arrangements of fundamental particles. Secondly and relatedly, it leads to a failure to distinguish the faculties or capacities of imagination and understanding from one another. This means that one fails to see that just what it is for the mind to grasp empirical reality as it truly and objectively is. For as the wax example from the Second Meditation has already intimated and the Fifth Meditation elaborated more closely, the essence of material things, hence their knowability, lies in their quantitative characters, which, as we know see, with the reduction of the sensuous qualities of material things to the subjective effects in us of these quantitative characters, is a mathematically describable reality hidden behind perceptual appearance. This quantitative essence is what is known when one knows reality as it truly and objectively is, and it is something grasped by the mind, specifically, by that purely discursive part of the mind which Descartes calls understanding in contrast to imagination. And because to know what material things truly and objectively are is to grasp this quantitative essence with the mind, it follows that the only truly effective method for investigating nature consists, first, in assuming the sensuous character of empirical reality to be the mere subjective expression of an underlying mathematical nature, in order then to devise experiments which turn individual perceptual experiences into reliable signs of this underlying mathematical nature.

§ 2: The Existence of Material Things and the Critique of Sense Experience Revisited

Descartes, having rejected the suggestion that he could account for his belief in the reality of material things by appeal to his having a faculty of imagination revisits the notion of sense experience. He writes that he is used to imagining

besides the physical nature which is the object of pure mathematics, many other things, such as colours, sounds, tastes, pain and the like, although none of them distinctly. Since I perceive them better by sensation – from which they seem to come to the imagination with the aid of memory – if I wish to discuss them properly, I have to discuss sensation too and see if from those things which are perceived in the type of thinking that I call sensation, I can derive an argument for the existence of physical things that is certain. (p.59)

What Descartes says here is no less puzzling that what he said at the very beginning of the Sixth Meditation. Given all that he claims himself to have shown in the previous Meditations, how can Descartes now speculate as to whether a certain argument for the existence of physical things might be derivable from a proper account of sensation and sense experience? Does not the argument of the First and Second Meditations show that no such argument can be had? Given this argument, why does Descartes even consider, at this point in his Meditations, the possibility that he might derive “an argument for the existence of physical things that is certain”?

As with his discussion of imagination and the sense in which having a faculty of imagination can be understood as committing its possessor to the existence of physical things, so, too, here: Descartes is presenting in fictitiously autobiographic, meditational form a certain views which he regards as commonly accepted but wrong and misleading. In his discussion of imagination and whether it provided a basis for rational belief in the existence of material things, the views at issue were actually Scholastic conceptions of ideas as pictures of reality. Descartes regards this view as incapable of providing anything more than a probable, not a certain inference to the existence of material things. Moreover, it implicates a false conception of nature (in that the sensual character of reality is seen as really out there, as a genuine player in the causal process of nature) and a false conception of mind (in that it amounts to an incapacity to distinguish clearly between understanding and imagining, which incapacity prevents one from seeing how to move beyond the false conception of nature it implicates).

At issue now are not any specifically philosophical views about ideas and the processing of ideas. Rather, at issue are what Descartes takes to be commonsense views about how we humans are naturally inclined to justify belief in material things, i.e., belief that the world which presents itself to us in perceptual experience actually exists. The important thing for Descartes about this commonsense conception is that it involves a mixture of truth and falsity. On the one hand, it accurately describes the proper function and role of perceptual experience, which is not to provide us with disinterested theoretical knowledge of how things objectively are in themselves, but to provide us with indications of whether objective things are likely to help or hinder us in our various purposive engagements and interactions with the world.⁸ On the other hand, it wrongly attempts to use this account in order to justify belief in the existence of the external world in which we contingently find ourselves⁹ and which we every so often attempt to know theoretically.

I shall first remind myself at this point of those things which, having been perceived by sensation, I formerly thought were true, and of the reasons why I thought they were true. I shall then review the reasons why I subsequently raised doubts about them. And finally, I shall consider what I should believe about them now.

First of all, I sensed that I had a head, hands, feet and the other members which compose the body that I considered as a part of myself or, perhaps, as myself in its entirety. I sensed that this body was surrounded by many other bodies by which it could be affected in various beneficial or harmful ways, and I judged the beneficial things by a certain sensation of pleasure and the harmful things by a sensation of pain. Besides pain and pleasure, I also sensed in myself hunger, thirst and other such appetites, and certain bodily inclinations towards happiness, sadness, anger and other similar passions. Outside myself, apart from the extension of bodies, their shapes and motions, I also sensed in them hardness, heat and other tactile qualities. In addition, I had sensations of light, colours, sounds, odours and tastes, by the variety of which I distinguished from one another the sky, the earth, the seas and other bodies. (p.59)

Here Descartes rehearses a part of his original, naïve system of belief which he thinks is quite right: his initial understanding of what perceptual experience accomplishes is that it enables him to sense the presence of bodies apart from his own which have the potential to affect his own body in various more or less beneficial ways. So perceptual experience is not there to give one objective knowledge of external reality. Rather, its defining function is simply to enable one to discriminate effectively between those things which will affect one positively and negatively in the pursuit of one’s various goals.¹⁰ For in fact it does not matter, from the point of view of survival and practical success, whether the red one perceives a fruit as having is a real feature of the fruit or not, provided only that, whatever the ontological status of the colour red, the fruit’s apparent redness should serve as a good guide whether it is edible or not. It seems wrong, therefore, to assume that in itself perceptual experience gives one access to how things really are. It only gives one reliable signals or cues for whether something is beneficial or harmful. This is not to deny that perceptual experience cannot be appropriated for purposes of knowing the true and objectively nature of the world; it is merely to insist that it needs to be made to perform this role, that is, it needs to be subject to clear direction and disciplining from outside—from the mind.

As I have pointed out previously, what this comes to is an idea upon which Immanuel Kant was later to place great emphasis, of which indeed he was to claim that it was constitutive of the scientific revolution and thus of the rise of distinctively modern science:¹¹ you do not get at the underlying causal reality of things simply by observing them. You have to observe reality in controlled experimental situations, for only then is your perceptual experience genuinely useful in deciding whether a particular hypothesis about reality is or is not wrong. These controlled experimental situations are built on the basis of quite powerful range of general assumptions about the nature of empirical reality which together constitute at least the basic tenets of a metaphysics of nature. For example, one assumes that nature is by and large an orderly place, that similar sets of circumstances will have similar effects, that one can in a given experimental situations ignore some features of the situation as irrelevant, and crucially also that one can sometimes ignore some features even though they are causally relevant, as when one ignores the distorting effect of, say, friction in order to be able to extract a general law or principle from similar experimental situations.¹² Once you have made assumptions like this, you can start to do experiments in a meaningful way because you have now constructed a situation in which perceptual experience can genuinely distinguish between features of the situation which are unique to it as the individual situation it is; and those features which it shares with similar situations, which therefore provide data for the identification of general laws common to all such situations.

But now Descartes rehearses some commonly held beliefs which he thinks are wrong:

Given the ideas of all those qualities which were presented to my thought and which were the only things that, strictly speaking, I sensed immediately, it was evidently reasonable to believe that I sensed various things which were clearly distinct from my thought, namely the bodies from which those ideas originated. For I experienced that those ideas would come to me without any consent on my part, so that I was both unable to sense any object, even if I wished to, unless it was present to my sensory organs and I was incapable of not sensing it when it was to my sensory organs and I was incapable of not sensing it when it was present. Since the ideas perceived by sensation were much stronger and more vivid and, in their own way, more distinct than any of those that I formed myself, it seemed impossible – when meditating carefully and intentionally on those that I noticed were impressed on my memory – that they originated from myself. Therefore, the only remaining option was that they originated from other things. Because I had no knowledge of those things apart from the very ideas that I got from them, nothing else could have occurred to me except that the ideas resembled the things. And because I also recall that I began using my senses before my reasons and since I saw that the ideas that I formed were not as vivid as those that I perceived by sensation and that, in most cases, they were composed of parts of the latter, I easily convinced myself that I had absolutely nothing in my mind which did not originate in sensation. (pp.59-60)

Note the very last sentence in this passage: “I easily convinced myself that I had absolutely nothing in my mind which did not originate in sensation.” This is a clear allusion to an old doctrine Descartes wants to oppose. Needless to say, it is a doctrine deriving from Aristotle and it was frequently formulated by Scholastic philosophers in the slogan that nothing is in the intellect which has not earlier been in the senses.¹³ As we know, Descartes thinks that his idea of God is innate in the sense that it comes with the territory of being a finite self-conscious subject such as he is. And what he is arguing here is that if one thinks of our belief in the existence of physical or material things in this fashion, one will not only have, as the First and Second Meditation have already shown, no certain argument for this belief but-and this is the conclusion of concern to him here in the Sixth Meditation-one will have an inadequate account of ideas. In particular, one will not see that not all ideas could have derived from sense experience, and in particular, that there are ideas which one simply must have in order to be able to grasp oneself as the finite thinking thing one is, in particular, an idea of that very special external thing which is God. Naturally, Descartes thinks that these two points are interrelated: if one thinks of all ideas as originating in experience, then one will not see that the idea of God is innate yet recognition that this idea is innate is essential to one´s having a certain, non-hypothetical or non-probabilistic account of the existence of the external world.

Finally, Descartes goes on to claim that if one thinks of our belief in the existence of physical or material things as arising in this fashion, one will also have a distorted, indeed false conception of how one’s character as thinking thing, that is, as having a mind, relates to one’s character as having a body.

It was also reasonable for me to judge that the body which, by some special right, I called my own belongs to me more than any other body. For I was unable ever to be separated from it, as I could be from other bodies; I sensed all my appetites and passions in it and for it; and finally, I was aware of pain and the titillation of pleasure in its part, but not in other bodies that were situated outside me. Why does a certain sadness of the mind follow from some unknown sensation of pain, and a certain happiness from a sensation of pleasure? Or why does the unknown tightening of the stomach that I call hunger advise me to eat food and a dryness of the throat advise me to take a drink, and so on for all the others? I clearly had no explanation except that I was taught this by nature. There is obviously no other connection (at least, none that I can understand) between the stomach tightening and the decision to take food, or between the sensation of something that cause pain and the thought of sadness that results from it. All the other things that I judged about the objects of the senses seemed to be taught by nature. I was convinced of this before I weighed up any of the reasons that could prove it. (p.60)

Evidently, Descartes is suggesting that when we think of our conviction in the existence of an external world as based in sense experience, our argument is not only uncertain and we are not merely led to an inadequate account of our ideas, i.e., of our concepts. We are also led to a false understanding of our character as having a mind as tightly bound up with our character as having a body-so much so, indeed, that we find ourselves at least unable to conceive how our mind could exist independently of our body. And so we find it hard to see how we could have an immortal soul since we surely only have a separable immortal soul if we can continue to exist as thinking, remembering, willing, etc., even when we no longer have a body.

Later, however, many experiences undermined little by little all my faith in the senses. For in some cases towers that seemed round from a distance appeared, close up, to be square, and very high statues standing on top of the towers did not seem tall to an observer on the ground. In countless other similar things I discovered that the judgements of the external senses were mistaken. And not only the judgements of the external senses, but also those of the internal senses. For what can be closer to me than pain? But I once heard, from those who had had a leg or arm amputated, that they still seemed to feel pain in the part of their body that was missing. Likewise, it did not seem certain in my own case that I had a pain in some limb even if I felt a pain in it. I recently added to these reasons for doubting two other much more general ones. The first was that I never believed I sensed anything while awake that I was not also able to think I sensed occasionally while I was asleep; and since I do not believe that the things I seem to sense while asleep come to me from external things, I did not see why I should give any more credence to things that I seem to sense while awake. The second reason was that, as long as I did not know or, at least, as long as I pretended not to know the author of my origin, I saw nothing to prevent me from being so constituted by nature that I was mistaken even about those things that seemed most true to me. As regards the reasons by which I was formerly convinced of the truth of sensible things, it was not difficult for me to reply to them. It seemed as if nature pushed me towards many things from which reason dissuaded me, and therefore I did not think that I should put much faith in what nature taught me. And despite the fact that the perceptions of the senses do not depend on my will, I did not think that I should conclude, for that reason, that they derived from things that are distinct from me; there may perhaps be some faculty in me, even if it is unknown to me, by which they are produced. (pp.60-61)

© Carleton B. Christensen, 2008, 2010, 2011, 2012, 2013 and 2014