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This book is corrected and edited by Al-Hassanain (p) Institue for Islamic Heritage and Thought


Douglas C. Long

The Philosophical Forum, 1:3 (New Series), Spring 1969, 259-273.


[Introduction] 3

I 4

II 7

III 11

Notes 15


After establishing his own existence by theCogito argument, Descartes inquires into the nature of the self that he claims to know with certainty to exist. He concludes that he is ares cogitans, an unextended entity whose essence is to be conscious. Although a considerable amount of critical effort has been expended in attempts to show how he thought he could move to this important conclusion, his reasoning has remained quite unconvincing. In particular, his critics have insisted, and I think quite rightly, that his claim to be "entirely and absolutely distinct"[1]from his body is not justified by the reasoning which he offers in its support.[2]Nevertheless, I also believe that the proffered criticisms of Descartes’ sketchy defense of his position fail to provide us with a full understanding of either the force of his argument or the errors which he commits in reaching his conclusion. In what follows I propose to explain how his arguments may be filled in with certain reasonable premises which make his reasoning concerning his 14 nature" appear less implausible and his mistakes more interesting than his critics have acknowledged.


One would perhaps expect an examination of Descartes’ doctrine that he is ares cogitans to give primary attention to explaining why he insisted that his essence is thought. In this paper, however, I wish to focus on his claim to be an unextended incorporeal entity. I do so because, if this latter point could be established, it would not be at all difficult to understand why he would feel committed to his being an entity which has a thinking nature and which is always thinking some thought or other. For if an entity lacks all corporeal properties, it seems necessary for it to have some other attributes if it is toexist at all.[3]But to say merely that it is nonextended does not help us, since this is only to repeat that it is not a corporeal entity. Thus the field is narrowed to psychological characteristics, the only positive "nonphysical" attributes which are ascribed to persons. (Notice that this is not merely the point that if any entity is to count as aperson we would expect it to have psychological features.)

Of course, it may be objected that the elimination of all but psychological characteristics still does not explain Descartes’ commitment to the view that a soul is always thinking or conscious, since an entity might have unactualized psychological capacities and dispositions. However, it is doubtful that this suggestion has any content where we are not speaking of a physical organism which may be temporarily without certain (or even any) conscious states while yet remaining alive and physically capable of such states. If an entity is imagined to have neither physical properties nor occurrent conscious states for a period of time, it is not at all clear what it would mean to say that "it" nevertheless had the power of thought during that time. This point is illuminated by the analogy which Descartes himself draws between thought and extension. In a letter to Anauld he explains that "by thought, therefore, I understand not a universal comprehending all the modes of thinking, but a particular nature which receives all the modes just as extension is a nature which receives all the shapes."[4]Following this parallel, it seems reasonable to argue that just as a material object exists only if extension is manifested in some shape or other, an immaterial soul exists only if consciousness is manifested in some thought or feeling.[5]Hence, given that Descartes thinks that he can prove that he is an immaterial soul, it should not be surprising to find him saying that thought constitutes the nature of intelligent substance[6]and that "the human soul is always conscious(cogitate) in any circumstances . ."[7]

It is much more difficult, however, to understand why Descartes thought that he could establish that he is an incorporeal entity. An argument for this conclusion is presented inThe Search After Truth where Polyander concludes one of his speeches with these words:

Yet, while entirely setting aside all these suppositions, this will not prevent my being certain that I exist. On the contrary, they confirm me yet more in the certainty that I exist and that I am not a body; otherwise, doubting of my body I should at the same time doubt of myself, and this I cannot do; for I am absolutely convinced that I exist, and I am so much convinced of it, that I can in no wise doubt of it.[8]

From this and similar passages in other places Norman Malcolm has extracted what he calls Descartes’ "argument from doubt."[9]

I can doubt that I have a body.

I cannot doubt that I exist.

Ergo, I am not a body."[10]

Malcolm demonstrates that the argument in this form is invalid by producing a counterinstance:

X can doubt that he is a Grand Master of the Elks.

X cannot doubt that he exists.

Therefore, he is not a Grand Master of the Elks.

Certain of Descartes’ remarks, however, suggest a somewhat more complicated but nevertheless related argument leading to a conclusion about his essence which can in turn be used to support his immaterialist thesis. For instance, in the Second Meditation he argues:

I myself, am I not at least something? But I have already denied that I had senses and body. Yet I hesitate, for what follows from that? Am I so dependent on body and senses that I cannot exist without these? But I was persuaded that there was nothing in all the world, that there was no heaven, no earth, that there were no minds, nor any bodies: was I not then likewise persuaded that I did not exist? Not at all; of a surety I myself did exist since I persuaded myself of something [or merely because I thought of something].[11]

The point he is trying to make here is summed up in an illuminating fashion inDiscourse IV where he says:

And then, examining attentively that which I was, I saw that I could conceive that I had no body, and that there was no world nor place where I might be; but yet that I could not for all that conceive that I was not.[12]

I take him to be arguing in these passages that he can conceive that there is no material world and that he has no corporeal attributes, without having to concede that he does not exist. The argument for this claim may be stated more explicitly as follows:

(1)   I can conceive of myself being conscious in a world in which there are no material entities.

But, by theCogito, if I am conscious at a given time, then I exist at that time.

(3)   Therefore, I can conceive of myself existing without a body, without corporeal attributes.

This is not to say merely that he can conceivably exist as a "subtle" physical entity, "like a wind, a flame, or an ether,"[13]but that he can conceivably exist without extension, without any bodily attributes at all. once this proposition is accepted, it is easy to justify the conclusion that bodily attributes do not belong to himessentially. We need add only the following steps:

(4)   Nothing that is logically impossible can be conceived.

(5)   Therefore, it is logically possible that I exist without bodily attributes.

(6)   No attribute without which it is logically possible that a thing exist is included in the essence of that thing.[14]

(7)   Therefore, no bodily attribute is included in my essence.

Arnauld objected that

the proof has proceeded only so far as to exclude from the nature of the human mind whatsoever is corporeal, not from the point of view of the ultimate truth, but relatively only to his consciousness (the meaning being that nothing at all was known to him to belong to his essential nature, beyond the fact that he was a thinking being) . . The problem is: how it follows, from the fact that one is unaware that anything else L(except the fact of being a thinking thing)] belongs to one’s essence, that nothing else really belongs to one’s essence.[15]

To this Descartes responded:

For although much exists in me of which I am not yet conscious (for example in that passage I did, as a fact, assume that I was not yet aware that my mind had the power of moving the body, and that it was substantially united with it), yet since that which I do perceive is adequate to allow of my existing with it as my sole possession, I am certain that God could have created me without putting me in possession of those other attributes of which I am unaware. Hence it was that those additional attributes were judged not to belong to the essence of the mind.

For in my opinion nothing without which a thing can still exist is comprised in its essence, and although mind belongs to the essence of man, to be united to a human body is in the proper sense no part of the essence of mind.[16]

Insofar as Descartes is claiming only that he has no physical attributesessentially this appears to be a plausible reply to Arnauld’s objection. I believe that many of his critics would go along with him this far, particularly those who would grant that our disembodied existence is at least conceivable or logically possible. What has seemed clearly unwarranted, however, is Descartes’ attempt to draw from his premises the much stronger conclusion that he is not a body or that he has no physical properties in fact. I will now try to show how the latter conclusion may be reached from the present stage of the argument.


In the Sixth Meditation Descartes offers the following argument in support of the thesis that he is an incorporeal entity:

And first of all, because I know that all things which I apprehend clearly and distinctly can be created by God as I apprehend them, it suffices that I am able to apprehend one thing apart from another clearly and distinctly in order to be certain that the one is different from the other, since they may be made to exist in separation at least by the omnipotence of God

From this he concludes that

just because I know certainly that I exist, and that meanwhile I do not remark that any other thing necessarily pertains to my nature or essence, excepting that I am a thinking thing, I rightly conclude that my essence consists solely in the fact that I am a thinking thing [or a substance whose whole essence or nature is to think]. And although possibly (or rather certainly, as I shall say in a moment) I possess a body with which I am very intimately conjoined, yet because, on the one side, I have a clear and distinct idea of myself inasmuch as I am only a thinking and unextended thing, and as, on the other, I possess a distinct idea of body, inasmuch as it is only an extended and unthinking thing, it is certain that this I [that is to say, my soul by which I am what I am], is entirely and absolutely distinct from my body, and can exist without it.[17]

But the distinctness of a person and his body expressed by these words and elaborated in textbook discussions of Cartesian dualism certainly does not appear to be entailed in any straightforward way by his not being essentially a physical entity. One is inclined to agree with Sydney Shoemaker when he insists that "from the fact that a thing could exist without physical properties, it does not follow that it does exist without them."[18]If Shoemaker is right, then the physical properties which appear to belong to me but without which I could still exist need not belong really to some other thing, i.e., my body. They may not be mine essentially, but they may still belong to me, not merely to my body.

Unfortunately Descartes’ explicit remarks in defense of his claim to be a non-extended entity fail to show how he would counter this objection. It is not even clear why he thought that he could establish that claim on the grounds that he could conceive of himself existing without a body. His central idea seems to be that he can use this chief premise to justify the claim that he has a clear and distinct idea of himself as a nonphysical being and this in turn is supposed to allow him to conclude that heis such a being. In thePrinciples, for instance, he says that "we can conclude that two substances are really distinct one from the other from the sole fact that we can conceive the one clearly and distinctly without the other."[19]And in reply to Amauld’s objections to his inference from his having a certain concept of himself to his being a soul, Descartes attempts to explain his reasoning more fully by arguing that if one can understand"two things to be complete in isolation from one another" this is"sufficient to establish a real distinction between them." [20] By"a complete thing I mean merely a substance endowed with those forms or attributes which suffice to let me recognize that it is a substance,"[21]i.e., something

which can exist by itself, without the aid of any other substance. No one who perceives two substances by means of two diverse concepts ever doubts that they are really distinct.

Consequently, if I had not been in search of a certitude greater than the vulgar, I should have been satisfied with showing in the Second Meditation that Mind was apprehended as a thing that subsists, although nothing belonging to the body be ascribed to it, and conversely that Body was understood to be something subsistent without anything being attributed to it that pertains to the mind. And I should have added nothing more in order to prove that there was a real distinction between mind and body: because commonly we judge that all things stand to each other in respect to their actual relations in the same way as they are related in our consciousness."[22]

He then goes on to explain that since, in the First Meditation, he found reason to doubt whether things are in their true nature exactly as we perceive them to be, his subsequent remarks about God and Truth serve to "further the conclusion as to the real distinction between mindand body, which is finally completed in Meditation VI."

One may be tempted to object that what we can distinguish "in thought" is one thing and what entities actually exist as distinct substances is quite another. Jerome Shaffer, for instance, argues that Descartes’ "inference that ‘mind and body are really distinct’ " is "fatally ambiguous . because ‘distinct’ can mean ‘intentionally distinct’ or ‘extensionally distinct’; he can prove the former but needs the latter for his conclusion."[23]But we must be careful not to be misled by Descartes’ own tendency to confuse the question of the distinctness of mind and body with the question of the distinctness of himself from any material entity. What he must show is thathe is not a body and thathe is a mind or a soul. And apparently what he means to argue in the Second Meditation is that he is not essentially a physical entity, from which he draws the conclusion that he has a clear and distinct idea of himself as an entity which lacks physical properties and is distinct from body. It is only in the Sixth Meditation, however, after having proved God’s existence, that he assured that the perceived distinction between himself and body does fact obtain. The "hyperbolical doubts adduced in the First Meditation" heretofore prevented him from being sure "that things are in their true nature exactly as we perceive them to be."[24]

Our problem then is to explain how Descartes can argue that he clearly and distinctly perceives that he is not a bodily entity at all, starting from the seemingly meager lemma that material properties are not included in his essence. I believe that there are reasonable premises which can be added to Descartes’ argument which make his conclusion appear quite plausible. But in order to introduce them we must first call into question an important assumption upon which criticism of his argument for being incorporeal is based. His critics seem to assume that all of physical attributes of a thing are contingently associated with that thing so that even if Descartes can conceivably exist without physical attributes this would in no way entail that he lacked such attributes in fact. But is it the case that all of the attributes of a material entity just happen to associated with it? With respect to certain properties the relation clearly is contingent. For example, it is contingent that an object is of this or that shape or of this or that size. Yet if we shift from the values of determinables to the determinables themselves, it becomes more difficult defend this contingency thesis. For instance, although a piece of wax may be cubical or spherical, it seems to be necessary that it have some shape or other if it exists at all. Or, as Descartes himself insisted, it seems to essential that a corporeal entity be extended in space. This is not to claim merely that

Necessarily (ifx is a corporeal entity then x is extended).

That would leave open the possibility that a given object is only contingently corporeal. What Descartes requires for his argument is the thesis that

(x) (ifx is corporeal then necessarily x is corporeal).

This is intended to express the point that one cannot conceive of a particular physical entity, a piece of wax, for example, as existing in time but without any of its physical properties. If one tries to think away the size and shape of a physical entity, one finds that instead of its becoming something nonphysical, it simply vanishes. And the same considerations may be used to show that we cannot understand the suggestion that this piece of wax might have existed without any of its physical properties. For this claim to make sense we would require an identity criterion that would permit us to identify that particular entity, whether or not it had physical attributes. But there seems to be no such criterion.

The metaphysical claim that an object, such as a piece of wax, is necessarily physical introduces a doctrine that is suspect in some quarters, namely the doctrine of "essential predication," so-called because it sanctions predicating a certain property of a thing essentially. Such predication employs the concept of modalityde re, which, in contrast to modalityde dicto, permits a modal operator to occur within the scope of bound variables.[25]One of the main objections to formulating statements using modalitiesde re is precisely that it commits us to the doctrine that some of the attributes of a thing belong to it necessarily, however that thing may be described or referred to, a doctrine which W. V. Quine has called "the metaphysical jungle of Aristotelian essentialism."[26]Fortunately there is no need for us to concern ourselves with the dispute regarding the legitimacy of quantified modal logic except insofar as the examples discussed here may serve as plausible illustrations of essentialist claims. I am interested not so much in the correctness of the traditional idea that certain properties of an entity may be present in it essentially as in the possibility of using this idea to understand better how someone might be tempted to argue as Descartes does for the distinctness of a person from his body.

The line of reasoning in support of his thesis that I wish to present has as its initial premise the proposition defended just above, which asserts that:

(1)  If something has corporeal attributes, then necessarily it has corporeal attributes.

Taking the contrapositive of this we have:

If an entity is not necessarily corporeal then it is not corporeal at all.

Instantiating proposition (2):

(3)   If Descartes is not necessarily corporeal then he is not corporeal at all.

In accordance with the conclusion of the "argument from doubt" which was discussed earlier we may now assert:

(4)   Descartes is not necessarily corporeal.

But (3) and (4) together permit us to conclude:

(5)   Descartes is not corporeal at all.

According to this argument Descartes can move from his initial premise which says that he can conceive of himself as existing in a world without bodies to the conclusion that he is himself an incorporeal entity. That is to say, if no corporeal attributes are part of his essence, then they are excluded from his constitution altogether. To say that he is not essentially corporeal or physical is to say that he is essentially incorporeal or nonphysical, a mind or soul, which is precisely the sort of thing which can and must exist without physical attributes. This contradicts Shoemaker’s claim that "from the fact that a thing could exist without physical properties it does not follow that it does exist without them." Moreover, we are now able to understand, I think, why Descartes claimed that his conception of himself as a noncorporeal entity was "complete" in a sense which permitted him to assert that he is distinct from his body. It is not merely that he could exist without physical properties but that his nature is of a character which leaves no room for the addition of such properties. It is incompatible with the possession of them.


I have tried to suggest a way in which to understand why Descartes thought that he couldprove that he is not a body merely on the basis of what he couldconceive himself to be. I am not suggesting, however, that he is successful in establishing his conclusion, for he makes a mistake at the outset that both leads him into his argument and vitiates it. But before discussing this error I wish to defend the foregoing argument against a line of criticism which partisans of the Strawsonian view of persons win be tempted to advance.

It might be said that Descartes neglects the possibility that his being a mind or a body are not the only alternatives open to him. He might be an entity of Strawson’s "mixed" type, an entity "such that to each entity of that type there must be ascribed, or ascribable, both states of consciousnessand corporeal characteristics" or such that both types of predicate "are equally applicable to an entity of that type."[27]Because a person in this way bridges the metaphysical chasm between mere bodies and mere souls, it is natural to suppose that a person could both have corporeal characteristics in fact and yet conceivably exist without them, in a purely psychological form. And if this is true, then Descartes "argument from doubt," as I have interpreted it, could not show him tobe an incorporeal, thinking thing.

In his descriptions of this "mixed" type of entity, Strawson does not make it clear whether the ascription to it of both P- and M-predicates is contingent or is necessary or whether these predicates differ in this respect; but in his discussion he allows that persons might survive bodily death and exist as "disembodied individuals."[28]At least he thinks the hypothesis is intelligible. Does this mean that we are to think of a person as an entity which can be stripped of its physical properties, including its having some shape or size, leavingthe very same entity with its psycho. logical characteristics only? Presumably Descartes would not question the conception of a distinct incorporeal individual; but he might well be moved to object that if a corporeal entity loses all of its corporeal attributes it no longer exists. Even if it had psychological capacities, there seems to be no reason to suppose that these could be left behind, like the grin of The Cheshire Cat, when the physical organism evaporated.

Furthermore, if one suggests that an incorporeal entity might come into existence upon the disappearance of an entity which has "mixed" attributes, this is not to conceive of the same entity’s losing its physical attributes. An incorporeal entity or soul is an essentially nonphysical entity, not the sort of thing that could have been or might become an extended entity. To say that something is without any size or shape is tantamount to saying that such predicates cannot be intelligibly applied toit at all. For a substance to lack dimensions altogether is for it to be in a completely different metaphysical category from extended objects, and it seems that we cannot make sense of the suggestion that one and the same substance can cross this major categorial boundary. If this is correct, then we seem to be justified in saying that a substance either has physical properties essentially or it is necessarily without them. This explains why the soul’s embodiment has traditionally been thought of in terms of being associated causally with a body which is itself the subject physical predicates only. We do not, indeedcannot conceive of its embodiment in terms of the acquisition of physical characteristics by an incorporeal entity, anymore than we can conceive of an extended entity becoming nonextended while still existing. Thus, even if we suppose that the being known as Descartes is of Strawson’s "mixed" type, it seems impossible that such an entity might become or have been a mere soul, something essentially nonphysical. Hence, if Descartes can conceive of himself existing as a soul, it appears that he cannot be a corporeal entity even of this "mixed" type.

We ought to be suspicious, nonetheless, of an argument which purports to give on virtuallya priori grounds a negative answer to Descartes’ question: "Am I so dependent on body and senses that cannot exist without these?"[29]And having labored to make as convincing as possible the latter steps in the chain of reasoning, those which at first seemed the most unconvincing, it is natural that our suspicion should now fall upon the initial move in the argument where Descartes claims to able to conceive of himself as existing without a body. Arnauld’s intuitions were correct, for it is at just this point that the rabbit is spirited into the hat ready to be drawn forth at the proper moment. But now, with the argument developed fully, we can see more clearly, I think, where Descartes has gone wrong. His fundamental mistake is that he failed justify the claim implied by his initial premise that the criteria which govern personal identity are such that he could conceivably exist without physical properties. One would expect him to explain what those criteria are prior to his attempting to say whether he is so "dependent" on body that he could not exist without it. But he does not explicitly consider this question. He simply asserts his initial premise without giving a conceptual justification for it.

I am not suggesting, of course, that Descartes or anyone else normal employs criteria of identity to determine who they are, although they might at times be brought to this, e.g., in cases of amnesia. What I am concern with here is the idea that in order to determine whether or not something can exist without certain properties, we need to know what sort of thing we are talking about and in particular what sorts of changes in it are permitted by its criterion of identity. In the present case, since Descart regards himself as both a conscious entity and a substance, two very different criteria of identity--or candidates for this role--may suggest themselves to him. On the one hand he may be conceiving of his identity in purely psychological terms as "whatever entity has personality P," where ‘P’ is defined by the set of thoughts, beliefs, memory impressions, and feelings that he has. Or he may think of the criterion of his identity as being that of the particular substantial entity which he is and which bears his psychological attributes. I wish to suggest that he unwittingly employs both criteria in his argument purporting to establish that he is an incorporeal substance, and that if he consistently applies but one criterion throughout, his argument fails, whichever criterion he chooses.

Let us consider first the possibility that Descartes supposes that he can use a psychological criterion of personal identity, one which he can apply from a purely first-person point of view. This supposition would explain why he feels justified in asserting without further investigation that a person who has the thoughts and feelings constituting personality P could exist without a body. If a certain set of psychological attributes are all that are required to identify a particular individual, then it seems to be possible for the person in question to be either a soul or a physical entity. If this is accepted, then Descartes, identified simply by personality P, could conceivably be a soul. But, as his critics have insisted, he cannot draw from this possibility the conclusion that he has in fact no physical attributes, because personality P might equally well belong to a corporeal subject. The psychological criterion of identity does not provide a conception of a "complete thing" in the sense he requires for his immaterialist conclusion, for it is still an open question what sort of thing it is--material or immaterial--which manifests the personality in question.

But how is this objection to be reconciled with our argument purporting to show that if Descartes can exist without corporeal attributes, he is not a material thing? The conflict between our defense of the dualistic argument and the point just made in criticism of it is only apparent. The criticism was based on the supposition that Descartes was using a psychological criterion of personal identity, whereas it is crucial to the argument we have been discussing that a nonpsychological criterion be introduced. This may seem surprising since the argument is meant to show something aboutpersons, and it is natural to assume that for this purpose a psychological criterion of identity is appropriate. But when Descartes asks whether he can exist without physical attributes, he is asking this question with respect to aparticular subject of psychological attributes. Thus his own identity quite naturally comes to be thought of in terms of the identity of a particular substantial entity, rather than solely in terms of the psychological attributes constituting personality P, which are universals."[30]

To illustrate this last point, let us suppose that Descartes had a twin who was reared in an environment exactly like his own and whose thoughts, and feelings, and memory-impressions were the same as his. Descartes would still insist that the first-person pronoun as used by him referred to himself as opposed to his twin. But if he is going to be able to refer significantly to himself as one person among other persons who may exist, he requires some principle by which such individuals can be individuated. In thePrinciples he remarks that "each of us conceives himself as a conscious being, and can in thought exclude from himself an other substance, whether conscious or extended…"[31]Hence, it appears that the required individuation derives from his being a particular substantial entity--either a soul or a body--and this in turn implies that the criterion of his identity is a criterion of substantial identity. And the main argument developed earlier indicated that the criterion of identity for substances is such that a particular entity which is material could not exist without physical attributes nor a particular soul with them. Thus if Descartes is conceived, not merely as a personality which could be manifested by either a physical organism or an immaterial soul, but as particular instance of one or the other type of substance, his dualistic conclusion that he is a soul does appear to follow from his premise concerning the possibility of his existing without his body, despite what his critics say.

Once the argument is clarified in this way, however, it becomes evident that we must challenge at the outset anya priori claim that he can conceive ofhimself existing in a world without matter. We must do so because we are no longer accepting a purely psychological conception of "himself," one which appears to leave open the question of his substantial nature. We are now supposing that he is a substance, and by the principle employed in our argument for his dualistic position, he can claim that he could exist without corporeal attributes only if he already knows that he is not a material entity. If he is a physical organism, for example, the criterion of his identity is that of the organism itself, at least so long as it has psychological characteristics. And, as argued earlier, the identity of such an organism cannot be preserved if it is bereft of its physical attributes. Therefore, if in his initial premise, he claims that he can conceive of himself as existing without such attributes, while at the same time regarding himself as a particular substance, he must know that he is a soul. In short, he must know that his conclusion is correct before he can assert his initial premise, thus begging the entire question in favor of mind-body dualism.

The most that Descartes’ "argument from doubt" in theMeditations shows is that he is able to conceive of an immaterial entity existing in a world without matter and having a psychological biography exactly like his own. But his being able to form this conception does not by itself permit him to claim thathe is such an entity, since he might, after all, be a physical organism. It is only by confusing a psychological and a substantial conception of "himself" that he seems able both to asserta priori that he could exist as a soul and then infer that he is a soul.


[1]C. Adam and P. Tannery (eds.), (Euvres de Descartes (Paris, 1897-1913), VII,

p. 78; E. Haldane and G. Ross (trans.), The Philosophical Works of Descartes (Cambridge, 1931), 1, p. 190. These works will be cited hereafter as AT and HR, respectively. With a few exceptions I have used the translations of Haldane and Ross.

[2]Hobbes, for example, objected to the inference, "I am exercising thought, hence I am thought" (AT VII, p. 172; HR 11, p. 61). More recently, Jaako Hintikka has spoken of Descartes’ "rash transition from cogito, ergo sum to sum res cogitans." See his "Cogito, Ergo Sum: Inference or Performance?" The Philosophical Review, 71 (1962), p. 10. In "Descartes’ Proof That His Essence Is Thinking," The Philosophical Review, 74 (1965), pp. 328-338, Norman Malcolm argues that none of Descartes’ explicit arguments for his being a res cogitans are correct or even plausible. Anthony Kenny offers an exceptionally lucid presentation of what he takesto be the errors inDescartes’ reasoning on this point in his recent study, Descartes(New York, 1968), 63-95.

[3]In the Principlesof Philosophy, Pt. 1, Principle 52 (AT VIII, p. 25; HR 1, p. 240)Descartes remarks that "nothing is composed of no attributes, properties, or qualities." I find even the concept of a particular immaterial entity obscure to the point of unintelligibility; but for the purpose of discussing Descartes’ argument I will not question the conceivability of such entities.

[4]AT V, p. 221. 1 have used Anthony Kenny’s translation of the passage in Descartes, op. cit., p. 68.

[5]I It is interesting to note that this point can also be turned against Descartes’ position. Hermann Lotze does just this in his Metaphysic (Oxford, 1887), 11, p. 317, when he asks: "If the soul in a perfectly dreamless sleep thinks, feels, and wills nothing, is the soul then at all, and what is it? How often has the answer been given, that if this could ever happen, the soul would have no being! Why have we not had the courage to say that, as often as this happens, the soul is not?"

[6]Principles of Philosophy, Pt. 1, Principle 63 (AT VIII, p. 30; HR II, p. 245).

[7]Corresp., No. 250 (AT 111, p. 423). The translation is from E. Anscombe and P.        Geach (eds.), Descartes: Philosophical Writings (Edinburgh, 1954), p. 266.

[8]AT X, p. 518; HR I, p. 319.

[9]Malcolm, op. cit., pp. 328-330.

[10]Ibid., p. 329. Later, in a summary of his discussion (p. 337), Malcolm expresses

the conclusion of the argument as follows: "Therefore my body does not pertain to my essential nature." But this conclusion is not the same, on the face of it at least, as "I am not a body," if the latter means "I have no physical properties at all."

[11]AT VII, pp. 24-25; HR 1, p. 150.

[12]AT VI, p. 32; HR 1, p. 101.

[13]In the Second Meditation Descartes remarks that he had formerly thought of the soul in these terms (AT VII, p. 26; HR I, p. 151).

[14]"Nothing without which a thing can still exist is comprised in its essence" (Replyto theFourth Set of Objections, AT VII, p. 219; HR 11, p. 97).

[15]AT VII, p. 199; HR II, p. 81.

[16]AT VII, p. 219; HR II, p. 97.

[17]AT VII, p. 78; HR 1, p. 190.

[18]Sydney Shoemaker, Self-Knowledge and Self-Identity (Ithaca, 1963), p. 19.

[19]Principles of Philosophy, Pt. 1, Principle 60 (AT VIII, p. 28; HR 1, p. 243).

[20]AT VII, p. 221; HR II, p. 98.

[21]AT VII, p. 222; HR II, p. 98.

[22]AT VII, p. 226; HR II, p. 101.

[23]Jerome Shaffer, "Persons and Their Bodies," The Philosophical Review, 75

(1966), p. 63.

[24]From his reply to Arnauld (AT VII, p. 226; HR 11, p. 101). I am in general agreement with Malcolm’s interpretation of Descartes’ claim that the separateness of mind and body is not proved until the Sixth Meditation. See Malcolm, op. cit., p. 326.

[25]The distinction between modality de re and de dicto is discussed in Georg H. Von Wright, An Essay in Modal Logic (Amsterdam, 1951) and in W. Kneale, "Modality de dicto and de re," in Logic, Methodology, and Philosophy of Science, ed. by Ernest Nagel, Patrick Suppes, and Alfred Tarski (Stanford, 1962), pp. 622-633.

[26]"Three Grades of Modal Involvement," Proceedings of the Xlth International Congress of Philosophy (Brussels, 1953), Vol. 14, p. 81.

[27]P. F. Strawson, Individuals (London, 1959), p. 104.

[28]Ibid., pp. 103, 115-116.

[29]Second Meditation (AT VII, p. 25; HR 1, p. 150).

[30]I do not believe that persons can be individuated by psychological states orpersonalities alone, without reference to particulars (substances). See B. A. 0. Williams, "Personal Identity and Individuation," Proceedings of the Aristotelian Society, Vol. 57 (1956-1957), pp. 229-252, for arguments supporting this contention.

[31]Principles, Pt. 1, Principle 60 (AT VIII, p. 29; HR 1, p. 244). I have used the less awkward translation by Anscombe and Geach here (op. cit., p. 194). 1 should add that I think that Descartes cannot successfully appeal to the idea of an immaterial substance in order to individuate persons who are psychological twins. But for purposes of criticism I will assume that his use of the word "I" picks out a unique substance, either physical or nonphysical, depending upon which sort of entity Descartes is.