Lecture Supplement on Descartes

The main problem in this Meditation is: “Does material substance exist?” or, perhaps better, “Can we know that material substance exists?” To provide an answer, he offers two proofs: an initial, or tentative one; and a second, more careful, one. After these proofs, Descartes distinguishes what we are “taught by nature” from what is known via the “natural light,” and discusses the composite of the body and mind which we call the “self”—what I will call the “body-mind.”

While it is natural to focus attention on the proof(s) regarding material substance, it is profitable to briefly hold on to what may well be a non-standard reading, and consider that this Meditation might well be considered to be primarily about the science of “psychology” rather than about the “physical sciences.” Thus far we have seen Descartes claim that the self exists, that it is, essentially, a thinking thing, that it has several faculties (notably understanding and willing), that “agent-causation” applies to it (though the extent of this is still under scrutiny), and that it is finite. In this Meditation we learn much more about the self, or mind—(and such learning, surely, falls under the general banner [now] of psychology). In this Meditation we learn about two other “faculties:” imagination and perception, we learn that it is in our perceptions of pleasure and pain (that is, certain of our “ideas”) that we get our best knowledge about the “external world” (which causes these ideas as they can not be caused either by us or by his deity), and that these “perceptions” are fallible, and caused by “other things.” As is the case with the wax experiment (though Descartes does not note this here as he does there), what we learn with the greatest certainty is things about our minds, and what is less (far, far less) “certain” is any understanding of “bodies.”

(A) He begins with a “tentative” proof which holds that our faculty of imagination shows that material things probably exist.

92 “...imagination...appears to be a certain application of the knowing faculty to a body immediately present to it, which therefore exists.”

-92-93 Distinguish understanding and imagining triangles, on the one hand, and understanding and imagining “chiligons” (one thousand sided figures), on the other. Consider also the case of pentagons. We can see that [94] “...a particular sort of effort on the part of the mind is necessary in order to imagine, one that I do not employ in order to understand.”

-Thus, there is something different from the mind upon which this faculty depends.

“...were a body to exist to which a mind is so joined that it may apply itself in order, as it were, to look at it any time it wishes, it could happen that it is by means of this body that I imagine corporeal things. As a result, this mode of thinking may differ from pure intellection only in the sense that the mind, when it understands, in a sense turns toward itself and looks at one of the ideas that are in it; whereas when it imagines, it turns toward the body, and intuits in the body something that conforms to an idea either understood by the mind or perceived by sense.”

“To be sure, I easily understand that the imagination can be actualized in this way, provided a body does exist. And since I can think of no other way of explaining imagination that is equally appropriate, I make a probable conjecture from this that a body exists.”

-Note the more reserved conclusion—compare his claim here with his knowledge of self, his deity, mathematics, or (again) of his deity!

-Note, also that there is here the kernel of the contemporary epistemological notion of inference to the best available explanation.^{^[2]}

Problem: we might imagine other explanations [which don’t seem to require bodies], and so we need a more careful consideration and a better argument.

(B) The “second,” and more careful, proof: removing the reasons for doubting:

94 “...I will review...all the things I previously believed to be true because I had perceived them by means of the senses and the causes I had for thinking this. Next I will assess the causes why I called them into doubt. Finally, I will consider what I must now believe about these things.”

1. What he believed and why—that his “sensory” ideas truly represented “things:”

-“…I sensed that I had a head, hands, feet, and other members that comprised this body which I viewed as part of me, or perhaps, even as the whole of me. I sensed that this body was found among many other bodies....”

-“...these ideas came upon me utterly without my consent, to the extent that, wish as I may, I could not sense any object unless it was present to a sense organ. Nor could I fail to sense it when it was present. And since the ideas perceived by sense were much more vivid and explicit and even, in their own way, more distinct that any of those that I deliberately and knowingly formed through mediation or that I found impressed on my memory, it seemed impossible that they came from myself. Thus the remaining alternative was that they came from other things. Since I had no knowledge of such things except from those same ideas themselves, I could not help entertaining the thought that they were similar to those ideas.”

-Perceptual problems: towers from afar; external and internal senses subject to error—phantom limb pains; dreaming; and the evil genius.

-95-96 “As to arguments that used to convince me of the truth of sensible things, I found no difficulty responding to them. For since I seemed driven by nature toward many things about which reason tried to dissuade me, I did not think that what I was taught by nature deserved much credence. And even though the perceptions of the senses did not depend on my will, I did not think that we must therefore conclude that they carry from things distinct from me, since perhaps there is some faculty in me, as yet unknown to me, that produces these perceptions.”

“But now, having begun to have a better knowledge of myself and the author of my origin, I am of the opinion that I must not rashly admit everything that I seem to derive from my senses; but neither, for that matter, should I call everything into doubt.”

-(i) “First, I know that all the things that I clearly and distinctly understand can be made by God such as I understand them. For this reason, my ability clearly and distinctly to understand one thing without another suffices to make me certain that the one thing is different from the other, since they can be separated from each other, at least by God.”

-(ii) Mind and body are (clearly and distinctly) separable—body is no part of my essence.

-(iii) The faculties of imagining and perceiving are distinct from me—as are the faculties of motion and taking on shape.

-96-97 (iv) “But it is clear that these faculties, if in fact they exist, must be in a corporeal or extended substance, not in a substance endowed with understanding. For some extension is contained in a clear and distinct concept of them, though certainly not any understanding. Now there clearly is in me a passive faculty of sensing, that is, a faculty for receiving and knowing the ideas of sensible things; but I could not use it unless there also existed, either in me or in something else, a certain active faculty of producing or bringing about these ideas.”

-97 (v) This active faculty can not be in me [that is, in me essentially and insofar as I am a thinking thing]—it does not presuppose thought and the ideas in question are frequently caused against my will.

-(vi) “Therefore the only alternative is that it is in some substance different from me containing either formally or eminently all the reality that exists objectively in the ideas produced by that faculty....Hence, this substance is either a body, that is, a corporeal nature, which contains formally all that is contained objectively in the ideas, or else it is God, or some other creature more noble than a body, which contains eminently all that is contained objectively in the ideas.”

-(vii) His deity can not be the substance in which this active faculty inheres (because he is not a deceiver) and, therefore, it must exist in bodies.

--“For since God has given me no faculty whatsoever for making this determination, but instead has given me a great inclination to believe these ideas issue from corporeal things, I fail to see how God could be understood not to be a deceiver, if these ideas were to issue from a source other than corporeal things. And consequently corporeal things exist.”

(C). We are taught “by nature” about bodies (and about the “body-mind”):

97 Regarding “particular” claims regarding corporeal bodies (that the sun is of such and such a size, what light, sound, and pain are, etc.), we can reach some understanding: in such cases, we are “taught by nature:”

Descartes discusses, in order of “clarity,” a number of things which are disclosed “by nature.” Here we see why he is ultimately willing to assign significant epistemological authority to this sort of “teaching:”

and surely there is no doubt that all that I am taught by nature has some truth to it; for by “nature,” taken generally, I understand nothing other than God himself or the ordered network of created things which was instituted by God….

The first thing he is so taught is that: “there is nothing that this nature teaches me more explicitly than that I have a body that is ill-disposed when I feel pain, that needs food and drink when I suffer hunger or thirst, and the like. Therefore, I should not doubt that there is some truth in this.”

98 Secondly, he maintains he is taught by nature that “…I by means of these sensations of pain, hunger, thirst and so on, nature also teaches not merely that I am present to my body in the way a sailor is present in a ship, but that I am most tightly joined and, so to speak, commingled with it, so much so that I and the body constitute one single thing.”

-In her “Cartesian Passions: The Ultimate Incoherence,” Marjorie Grene may go further than Descartes does here maintaining that for him we know the mind and body: “...by natural light, but [the union of the mind and body] only through that ‘natural impulse’ which Descartes has warned us in the Third Meditation has so often misled us, not only in the search for truth but in the choice of goods. It seems predestined, therefore, that the interrelations of mind and body, the events of our lives as united minds and bodies, that our human histories, in short, and therefore our human being, can be comprehended only in this relatively obscure, non-scientific and instinctive rather than in that luminous, intellectual way. As Descartes emphasizes, the union of the body and mind is accessible to us, not through science, but through the experience of ordinary life; and it is precisely the experience of everyday life that has been definitively undermined in the programmatic doubt of Meditation One, followed by the demonstration in Meditation Two of its incurable confusion.”^{^[3]}

Finally, “...there are many other things that I seem to have been taught by nature; nevertheless it was not really nature that taught them to me but a certain habit of making reckless judgments. And thus it could easily happen that these judgments are false....to ensure that my perceptions in this matter are sufficiently distinct, I ought to define more precisely what exactly I mean when I say that I am “taught something by nature.” We are “taught by nature” to:

-“but it does not appear that nature teaches us to conclude anything besides these things, from these sense perceptions unless the intellect has first conducted its own inquiry regarding things external to us. For it seems to belong exclusively to the mind, and not to the composite of mind and body, to know the truth in these matters.”

-“...I use the perceptions of the senses (which are properly given by nature only for signifying to the mind what things are useful or harmful to the composite of which it is a part, and to the extent that they are clear and distinct enough) as reliable rules for immediately discerning what is the essence of bodies located outside us. Yet they signify nothing about that except quite obscurely and confusedly.”

-I may be mistaken even about pleasure and pain—pleasant taste and poison, the ill who desire food or drink which will make them worse! This means that this “knowledge” is not the same sort of knowledge as that which he gets when he confines himself to the mental domain!

100 While a poorly designed clock doesn’t tell time well, we can not conclude that our bodies have been poorly designed (that they don’t “tell well” the nature of external things). To see that his deity is not to be “blamed” for misconstruction, we must better understand the mind, body, and body-mind.

-the body is a composite such that “remote” movements require “intermediate” movements, and the sensory “results” could be achieved by the intermediate movements only (pain “in foot” requires transmission through intermediates, which could alone cause the pain).

-102 “...notwithstanding the immense goodness of God, the nature of man, insofar as it is composed of mind and body, cannot help being sometimes mistaken. For if some cause, not in the foot but in some other part through which the nerves extend from the foot to the brain, or perhaps even in the brain itself, were to produce the same motion that would normally be produced by a badly injured foot, the pain will be felt as if it were in the foot, and the senses will naturally be deceived.” Ditto, of course, for “dryness of the throat” in an ill individual.

-103 “...I know that all the senses set forth what is true more frequently than what is false regarding what concerns the welfare of the body. Moreover, I can nearly always make use of several of them to examine the same thing. Furthermore, I can use my memory, which connects current happenings with past ones, and my intellect, which now has examined all the causes of error. Hence I should no longer fear that those things that are daily shown me by the senses are false. On the contrary, the hyperbolic doubts of the last few days ought to be rejected as ludicrous.”

--“This goes especially for the chief reason for doubting, which dealt with my failure to distinguish being asleep from being awake. For I now notice that there is a considerable difference between these two; dreams are never joined by the memory with the other actions of life, as is the case with those actions that occur when one is awake....and when I connect my perception of them with the rest of my life, I am clearly certain that these perceptions have happened to me not while I was dreaming but while I was awake. Nor ought I have even the least doubt regarding the truth of these things, if, having mustered all the senses, in addition to my memory and my intellect, in order to examine them, nothing is passed on to me by one of those sources that conflicts with the others. For from the fact that God is no deceiver, it follows that I am in no way mistaken in these matters. But because the need to get things done does not always permit us the leisure for such a careful inquiry, we must confess that the life of man is apt to commit errors regarding particular things, and we must acknowledge the infirmity of our nature.”

Notes: [click on note number to return to the text for the note]

[1] This supplement, and the others for Descartes’ Meditations on First Philosophy, reference the pages in Donald A. Cress’ translation in René Descartes: Discourse on Method and Meditations on First Philosophy, Fourth Edition (Indianapolis: Hackett, 1998. They were developed over 40 years of teaching, however, and the citations are sometimes to other translations. In addition emphasis (italics, underlines, and bolding are regularly added to citations to help direct your attention.

[2] Cf., Gilbert Harman, Thought (Princeton: Princeton U.P., 1973) His discussion on pp. 130-141, and 155-172 provides a concise account of this orientation.

[3] Marjorie Grene, “Cartesian Passions: The Ultimate Incoherence,” in her Descartes (Minneapolis: Univ. of Minnesota, 1985), pp. 23-52, p. 33. Emphasis is added to the passage.