Descartes’ Dualism: Correcting Some Misconceptions

Andrea Christofidou. Journal of the History of Philosophy. Volume 39, Issue 2. April 2001.

[Those who do not bother to grasp the proper order of my arguments and the connection between them, but merely try to quarrel with individual passages, will not get much benefit from the book. (Descartes [AT VII 379)

For the greater part of this century, philosophy has relegated Descartes to the role of anti-hero, with philosophers defining their positions against “what are seen as deeply flawed Cartesian paradigms.” This stance is succinctly captured in a recent paper by Bernard Williams:

[Descartes’] works (or a few of them) are read (or partly read) as the most challenging and informative misleading example of what is to be rejected […] He is typically presented […] as one who simply had a weakness for scepticism, or perhaps for mathematical certainty […] or whatever misconception particularly impresses the teacher as providing the source of scepticism: a student will reasonably conclude, not only that Descartes is a fool, […] but more damagingly, that a subject which […] thinks it important that one should now read [his] works […] cannot be a very serious subject.

If having a weakness for scepticism has been seen as one flaw in Descartes, having a weakness for dualism has undoubtedly been seen as another; my concern here is solely with the latter. My primary focus is on the claim (which I call the standard claim), that Descartes based his dualism on a fallacious argument found in the Discourse Part IV (AT VI 32-33) which involves a move from what he can or cannot doubt to a metaphysical conclusion. This argument is standardly referred to as the argument from doubt.

This is not the first investigation into the Discourse argument, but the major problem with previous examinations of the argument is their approach: the examinations and reformulations are not of Descartes’ argument but of Arnauld’s version of it, which has been seen as involving a fallacious application of Leibniz’s principle. Inevitably the results tend to fall in line with the general consensus: even if the argument from doubt (however reformulated) is not Descartes’ only argument for dualism, it is one of them, and it is fallacious. The approach I adopt here is different since my main concern is not with yet another reformulation of Arnauld’s version of the argument, but with a critical examination of the standard claim itself. I contend that the standard claim derives its force mainly from a number of misconceptions of Descartes’ arguments; it derives its persistence largely from a general acceptance of an anti-dualist paradigm-the adoption of the “dogmatic rule that dualism is to be avoided at all cost” and the assumption that physicalism is true: “Many philosophers do not give any arguments for physicalism, but take some such position for granted in all their reasonings.” Paul Churchland, for instance, claims that our conception of mental phenomena “constitutes a radically false theory, a theory so fundamentally defective that both the principles and the ontology of that theory will eventually be displaced. One asks (with David Ross), if reason has made such an egregious error about itself, what is it that reassures Churchland that reason can be trusted in its power to know anything at all?

My central task is two-fold: (a) to argue that correcting the misconceptions shows that the Discourse argument is not only immune to the standard claim, but is in fact not an argument from doubt at all-indeed, there is no argument in Descartes, much less the argument for dualism, which is established on the basis of doubt, or of ignorance-and (b) to show that the Discourse argument is not an argument for dualism. As a result of examining the standard claim, further objections come into focus, but given the scope of this paper I deal with only some of them; in particular I do not discuss the most controversial one, the incorporeality objection, since any plausible defence of it would require a paper in itself. As John Cottingham puts it: “That Descartes’ metaphysical manoeuvres fail to provide a plausible defence of the incorporeality thesis is hardly a new complaint.” By correcting the misconceptions on which the standard claim is based, however, I provide a framework for addressing the incorporeality objection and for redressing the imbalance prevalent in our current philosophical climate.

1. The Standard Claim

In a passage in Part IV of the Discourse (hereafter simply `the Discourse passage’) Descartes argues as follows:

I saw that while I could pretend that I had no body and that there was no world and no place for me to be in, I could not for all that pretend that I did not exist. I saw on the contrary that from the mere fact that I thought of doubting the truth of other things, it followed quite evidently and certainly that I existed […] From this I knew I was a substance whose whole essence or nature is simply to think, and which does not require any place, or depend on any material thing, in order to exist. Accordingly this ‘I’ [that is, the mind … ] is entirely distinct from the body, and […] would not fail to be whatever it is, even if the body did not exist. (AT VI 32-33)

The standard interpretation and ultimate rejection of Descartes’ argument, however, pivots on and follows that of Arnauld in the Fourth Set of Objections: (AT VII 198)

I can doubt whether I have a body, and even whether there are any bodies at all in the world. Yet for all that, I may not doubt that I am or exist, so long as I am doubting or thinking. Therefore I who am doubting and thinking am not a body. For, in that case, in having doubts about my body I should be having doubts about myself.

The Discourse passage reveals a number of difficult issues in Descartes’ work, which must be carefully considered before the passage is dismissed as fallacious.

Most authors, both in his own time and at present, seem unaware that Descartes’ arguments are not arguments from doubt, or from imagination, but only from clear and distinct understanding of what can and cannot be doubted-in fact he explicitly rejects any argument that attempts to establish dualism on the basis of imaginability, fantasy fits, ignorance, or doubt. For example, he says, “it would indeed be a case of fictitious invention if I used my imagination to establish that I was something or other” (AT VII 28). The use of one’s imagination is a clear indication that one has not reached the level of clear and distinct conception which is necessary for objective or real possibility. Not only does it not follow that what is imaginable is objectively or really possible-much less objectively certain-since the imagination offers no real clue as to the essence or nature of things, but also the imagination, he argues, is open to doubt. Most authors also seem unaware of the various distinctions that are central to Descartes’ arguments. And despite what appear to be genuine attempts to get absolutely clear about the Discourse argument, such attempts are directed at Arnauld’s version of the argument. Moreover, such attempts betray a noticeable lack of awareness of the centrality of the notion of clear and distinct conception, and of the complexity of the issues involved in the Discourse passage. At times, some authors express an unwillingness to enter into what they consider to be “the details of the scholarly debate,” but this seems at best a rather poor excuse given the centrality of the issues involved and their claim that his argument for dualism is fallacious.

2. Stage-Setting

Before I begin an examination of the standard claim and of the issues involved in the Discourse passage, I shall set out the framework within which Descartes’ arguments are best discussed and understood, and bring out the distinctions at the heart of the issues to be explored.

First, when considering Descartes’ arguments it is crucial that one follow the strategically important order of the analytic method (see Second Replies, AT VII 155). That is, one should heed the basic distinction that he draws between the order of logical demonstration and the order of effective exposition, which he expressed clearly in his letter to Mersenne (24 December 1640):

It should be noted that throughout the work the order I follow is not the order of the subject-matter, but the order of the reasoning. This means that I do not attempt to say in a single place everything relevant to a given subject, because it would be impossible for me to provide proper proofs, since my supporting reasons would have to be drawn in some cases from considerably more distant sources than in others. Instead, I reason in an orderly way from what is easier to what is harder, making what deductions I can, now on one subject, now on another. […] The order of the subject-matter is good only for those whose reasoning is disjointed, and who can say as much about one difficulty as about another. (AT III 266-7)

Second, it is important to distinguish between his epistemological arguments and his metaphysical arguments, and their degrees of commitment. The epistemological arguments are bound up with an “order corresponding to [one’s] own perceptions”-they are what I call subjectively certain. Subjective certainty, however, is not psychological certainty, nor is it any arbitrary state of subjective perceptions, or a matter of introspecting one’s psychological or sensory experience. Introspective sensory experience, contrary to the received view in the philosophy of mind, is rejected by Descartes as a basis for truth and certainty, since he sees introspection (which he calls internal sense) as being just as unreliable as the external senses. (AT VII 76-77). The truth of his judgments does not depend upon how he feels, or upon his seemings, or upon his sensory conscious awareness, or upon a state of doubt. Rather, in subjective certainty the emphasis is on the logical or intellectual form of cognition, not on its psychological character; it involves having good reasons to know that a proposition is true, reasons that depend upon what is clearly and distinctly understood-that is, what is true. As Williams argues, truth and certainty cannot come apart in Descartes’ project without rendering that project incoherent. The distinction appropriate here is that between cognitio and scientia; both are true and cannot be contradicted, but the latter is objectively true and certain (with the guarantee of God), while the former is subjectively true and certain, that is, time-bound, and objectively possible (and does not need the guarantee of God). In light of all this it is astonishing that Descartes has been, and still is, saddled with a sense-datum theory, the myth of the given, and an introspective epistemology. It seems that such wild attributions have been and are still made because of our tendency to read him from our own post-Humean empiricist viewpoint, and because of our failure to distinguish between what Descartes calls the “natural light of reason”-a process of reasoning that can be conceived to be valid by anyone who reasons or thinks at all-and the phenomenological quality of consciousness. For example, Anita Avramides writes: “Descartes claimed that indubitability was the mark of a special […] and peculiar relationship to his own mental life.” We are not told where Descartes claims this; instead, Avramides continues:

We might say that what is special about the subject’s relation to his own mental life is that all aspects of that life are presented […] with a certain phenomenological quality. […] Descartes no sooner makes this observation than he misinterprets it, and in doing so, he moves from having a subjective conception of mind to embracing an objective conception of it […]. The irony is that in seeking to explain this special relation, the Cartesian loses sight of it.

The irony is that in misunderstanding Descartes’ arguments, contemporary philosophers lose sight of the subtlety of his distinctions and the rigour of the order of reasoning. Consequently, they attribute to him views that he does not hold.

An idea is clear when it is present to the careful and attentive mind-that is, when it has undergone rigorous scrutiny. It is this requirement that is implicit in Descartes’ reply when he says: “it requires some care to make a proper distinction between what is clearly and distinctly perceived and what merely appears to be” (AT VII 462). It should be obvious that ‘perceive’ in this context does not mean sensory perception or observation, but intellectual perception, which involves clarity and distinctness, and which is connected with understanding why things are or must be thus and so. An idea is distinct when it is not mixed with any ideas that are not clear, or which are extraneous to the nature or status of what is clearly understood. A clear and distinct conception “is not a conception of the imagination, that is to say, a conception that is in the mind merely in the form of an image or set of images.” As Descartes points out in a letter to Mersenne (July 1641 ),what marks the distinction between imagination (even as a modus cogitationis) and conception or understanding is not whether their respective ideas “are expressed by terms or by propositions [… since] they can both be expressed in either way.” Rather, it is “the manner of conceiving them which makes the difference” (AT III 395; see also section I above). And in the Fifth Set of Replies, he stresses that “the powers of understanding and imagining do not differ merely in degree but are two quite different kinds of mental operation” (AT VII 385). It is evident then that clear and distinct ideas are neither images nor iconic thoughts. Henceforth, I shall use the terms `clear and distinct idea,’ `clear and distinct conception,’ and ‘proposition’ interchangeably. Furthermore, a clear and distinct conception is concerned with the question “What is it?” and not with the question “What is it like?”; it is a conception of real essence in abstracto, not of the very existence of things in their de facto independence of the meditator’s conception of them. This distinction is crucial since it clearly shows that Descartes’ clear and distinct conceptions do not have any illegitimate existential import. One can reason about the essence of a triangle or a physical object (a piece of wax) without being committed to the existence of triangles or of physical objects. Existential commitments (except in the cases of the cogito and the existence of God) can be guaranteed only by God-hence the centrality to the project of God’s role as a metaphysical bridge from objective possibility to objective certainty. This is instructive, for “the possibility then arises-one fully exploited by Descartes, of course-that even when we are sensorily aware of sensible objects, more is involved in the total cognitive situation than the mere having of sensations.” This is the insight which Kant explores through his emphasis on the dual role of sensibility and understanding.

Clarity and distinctness do not constitute a methodological maxim enunciated only problematically in the Regulae (Rule Three, AT X 368), but a joint criterion of truth (established by means of the self-evidently true cogito, and) asserted categorically. Propositions satisfying such a criterion delineate real notions graspable by the intellect, and cannot undermine the relation between conceiving and understanding, since whatever is clearly and distinctly conceived cannot be doubted-the ‘cannot’ is logical and not psychological, since Descartes explicitly denounced the psychologism of the Schools (see Regulae, Rule 2, AT X 365, and Rule 4(A) AT X 372-3).

Thirdly, it should be evident that Descartes’ methodical doubt has a particular metaphysical application and is put forward positively as an injunction to guide one in the attainment of knowledge; it has nothing to do with ignorance, or with psychological doubt that arises from one’s personal predicament: “no matter who the perceiver is, nothing can be clearly and distinctly perceived without […] being true” (AT VII 462). What can be drawn from all this is that a clear and distinct perception is: (a) true, and proof against contradiction; whatever is clearly and distinctly perceived cannot be altered by any further investigation; and (b) time-bound in the sense that the meditator can be certain of his conception while the intellect is carefully and attentively concentrating on it. Taking conceivability (not imaginability) as sufficient for logical possibility, it follows that what is clearly and distinctly conceived is genuinely or objectively possible, and genuine or objective possibility is true possibility.  As with all Descartes’ arguments, it is important to get the direction of reasoning right: it is not that clear and distinct conceptions are true because we conceive them as such; rather, we conceive them as such because they are true (see also Section 6 below).

Thus the meditator will be certain of his judgments only if they are based on clear and distinct ideas, and he will proceed only from arguments that are based on what he can clearly and distinctly understand, refraining from making any claims about what he does not know or understand, and from drawing conclusions in the weighty sense. These are exigent requirements of his project. The upshot is that those of Descartes’ arguments that are based on an “order corresponding to [one’s] own perceptions” are epistemological, and their commitments are minimal, that is, objectively possible.

Fourthly, Descartes’ metaphysical arguments are based on “an order corresponding to the actual truth of the matter,” and in the case of a real distinction they are bound up with the notion of apartness. Their commitments are weighty-they give the meditator (with the guarantee of God) what Descartes calls scientia or knowledge, a formal requirement of which is objective certainty and not just objective possibility.

Fifthly, we need to understand what a real distinction is and what dualism is. I confine myself to some preliminary remarks here and expand on them in Section 5 below. Real distinctness is primarily an ontological thesis-it has to do with ontological or numerical separability (since it is logically impossible for a thing to exist apart from itself). Real distinctness ontologically does not entail dualism. (The distinction between the infinite substance, God, and finite created substances is special, since they need the concurrence of God in order to exist. Whatever the issues involved in this, however, they are not relevant to my present purposes, since my concern is with finite substances.)

Dualism is a metaphysical thesis-it is concerned with metaphysical distinctness, that is, essential or real distinctness in kind. Dualism depends not only upon real distinctness ontologically-that is, on a clear and distinct understanding that complete things or substances are separable-but also on a clear and distinct understanding of attributes, and an attribute is what constitutes the nature or essence of a substance. Both ontological distinctness and dualism are based “on an order corresponding to the actual truth of the matter.”

3. Critique of the Standard Claim

With this groundwork in place, I return to the Discourse passage quoted at the beginning of Section i above, but generally found in the literature in a form paraphrased by Arnauld in the Fourth Set of Objections (AT VII 198); so understood, the argument would indeed involve a fallacy-the substitutional fallacy.

Before committing the passage to the flames, however, we should carefully consider Descartes’ argument, beginning first with how he intended it to be understood. In the Preface to the Meditations he writes:

It was not my intention to make those exclusions [i.e., of everything else that could be said to belong to the nature of mind] in an order corresponding to the actual truth of the matter (which I was not dealing with at that stage), but merely in an order corresponding to my own perception […]. So the sense of the passage [from the Discourse] was that I was aware of nothing at all that I knew belonged to my essence except that I was a thinking thing, or a thing possessing within itself the faculty of thinking. (AT VII 8)

This passage relates to another of Descartes’ replies. In the Fifth Set of Replies he refers to the Discourse passage and to similar passages, and stresses that “belonging to me” is clearly quite different from “belonging to the knowledge which I have of myself” (AT VII 357)-the former is a metaphysical claim, the latter is epistemological. This distinction is crucial to rebutting the standard claim. Descartes’ argument in the Discourse draws on the latter formulation; it is an argument based on what belongs to the knowledge which he has of himself at that stage of his enquiry-on “an order corresponding to [one’s] own perception.” Such perceptions are, nevertheless, clear and distinct and thus sufficient for the objective possibility that the mind “would not fail to be whatever it is, even if the body did not exist” (Discourse AT VI 33). It is not an argument based on “an order corresponding to the actual truth of the matter,” with which the meditator “was not dealing […] at that stage”; that is, it is not an argument directly about the nature of things, but an argument about the meditator’s conception and understanding of their nature, a distinction which Williams brings out very clearly. Despite all this, Arnauld still asks:

From [the above response] it is clear that the objection still stands in precisely the same form as it did before, and that the question he promised to answer still remains outstanding: How does it follow, from the fact that he is aware of nothing else belonging to his essence, that nothing else does in fact belong to it? (AT VII 199)

He goes on to “confess that [he is] somewhat slow,” but still insists that he has been unable “to find anywhere in the Second Meditation an answer to this question” (op. cit.). This is unsurprising, since Descartes’ arguments in neither the Discourse nor the Second Meditation are cast in the form that Arnauld represents them. Given that the intention was not to exclude everything else that could be said to belong to the nature of mind in an order corresponding to the actual truth of the matter, with which he was not dealing at that stage, and given that the arguments are based on an order corresponding to one’s own conception, and not to the actual truth of the matter, the arguments are epistemological. No metaphysical conclusions are drawn (much less conclusions based on ignorance; I come back to this below). It follows that the argument in the Discourse should properly be seen as Descartes intended it: an epistemological argument with minimal commitments. Its commitments are subjectively certain (see Section 2 above), and hence objectively possible.

It might be said that even if this response goes some way towards rebutting Arnauld’s objection, it does not provide a full refutation of it. To meet this objection we need to ask whether the argument is, as is standardly assumed, `an argument from doubt’. Understanding the direction of Descartes’ order of reasoning is a key to answering this question. Enquiry can take various forms; in Descartes’ project it takes the form of moving from what one clearly understands, not from what one does not understand, is ignorant of, or doubts. Note the passage in the Second Meditation where, having shown that at least he is certain of his own existence and that the attribute of thought cannot be separated from him, Descartes raises the question of what else he might be:

yet may it not perhaps be the case that these very things which I am supposing to be nothing, because they are unknown to me, are in reality identical with the ‘I’ of which I am aware? I do not know, and for the moment I shall not argue the point, since I can make judgments only about things which are known to me. (AT VII 27; italics added) Beginning an enquiry from an order corresponding to what one can clearly and distinctly conceive or understand, and making judgments only about things which are known to one, is a way of providing oneself with reasons to know that a proposition is true, and with reasons to know why it is true and cannot be doubted. It is also a way of providing oneself with reasons to doubt what, at that stage, can be doubted, but ‘doubting’ in this sense does not mean ignorance; it means having reasons to doubt, that is, clearly understanding what can and cannot be assented to at each stage of one’s enquiry. Understanding is bound up with aitias logismos-with scrutinising and working out the reason for one’s conception that p is, or must be thus and so; it involves not only intelligibility, but also explanation, which in the case of subjective certainty, as I explained in Section 2, entails objective possibility. The natural light of reason, which is not just an arbitrary assumption but a precondition of philosophical enquiry, is trained on the certainty that the meditator is entitled to have concerning something that he clearly and distinctly understands.

The Discourse passage shows clearly that the premises of the argument are concerned with what Descartes understands can or cannot be doubted at each stage, and not with what he is ignorant of, or what he can and cannot doubt, as Arnauld mistakenly interprets them. The way that the premises are formulated shows the order of his reasoning: “I resolved to …. ,” “I noticed that … ,” “I examined attentively,” ‘I saw that while I could pretend that … ” “I saw on the contrary that from the mere fact that I thought of doubting . . ” “From this I knew…” (AT VI 32-33). There is no premise in the argument that begins with: ‘I can doubt…” or “I cannot doubt …” which is how Arnauld and the standard-claim defenders represent the argument. The Discourse argument does not move invalidly from what he can and cannot doubt, or is ignorant of, to any conclusion (epistemological, or metaphysical); rather, it moves validly from what he understands can and cannot be doubted (an understanding based on an order corresponding to his clear and distinct perceptions) to a conclusion about what belongs to the knowledge which he has of himself at that stage of his enquiry, not to what belongs to him. It is therefore not an argument from doubt, but an argument from clear understanding of what can and cannot be doubted. What the intellect leads one to think or understand or know at that stage are certain truths about what belongs to the knowledge that one has of oneself while having reason to doubt certain other truths-e.g., truths about the body. Understanding does not depend upon having reasons to doubt; the direction is the other way: having reasons to doubt depends upon what the intellect leads one to understand (see First Meditation AT VII 18). The conclusion of the argument is, like the premises, epistemological.

Furthermore, the conclusion of the Discourse argument reveals two more subtle but important points: one about Descartes’ conception of himself as something, a res or substance, and of the attribute of thought which cannot be doubted while he is thinking, and one about his conception of the nature and status of a mental substance qua substance: something, he argues, whose nature is to think and “which does not require any place, or depend on any material thing, in order to exist” (AT VI 33), since the existence of any created or finite substance requires only the concurrence of God (see Principles, pt.1 51). Therefore, the clause “which does not require any place, or depend on any material thing, in order to exist” is not about what belongs to him; it is not about the actual truth of matter, but about his conception and understanding of the nature and status of a mental substance. When he concludes in the Discourse passage: “From this I knew I was a substance […],” a conclusion based on an order corresponding to his own perceptions, he means neither more nor less than that this res or substance is the subject of attributes, the subject of thought that can indubitably be said to exist at the time that it is thinking (see also Section 4 below). And when he finally concludes: “Accordingly this ‘I’ […] is entirely distinct from body” he means that, whatever the actual truth of the matter might be, on the basis of an order corresponding to his own perceptions, he knows first that he is something, a res or substance, to which he refers as ‘I’; he is absolutely right in doing so, since, to put it in our terminology, the self-reference principle of ‘I’ “tells us that the object of an ‘I’-thought is its subject. ” And he knows secondly that he is entitled to uphold the objective possibility that this T (qua thinking being) is entirely distinct from body. No weighty metaphysical conclusions are drawn.

The point can be made vivid by considering a conclusion that Descartes draws in the Second Meditation: “I am, then, in the strict sense only a thing that thinks” (AT VII 27), and the objection that has been urged against it by philosophers who see it as illegitimate. In the Appendix to the Fifth Set of Objections and Replies, he argues that he did not intend

at all to mean an entire exclusion or negation, but only an abstraction from material things; for I said that in spite of this we are not sure that there is nothing corporeal in the soul, even though we do not recognize anything corporeal in it. Here my critic [Gassendi] is so unfair to me as to try to persuade the reader that when I used the phrase `in the strict sense only’ I meant to exclude the body, and that I thus contradicted myself afterwards when I said that I did not mean to exclude it. (AT VII 215)

He intended the phrase to mean “strictly speaking,” or “on the basis of what belongs to the knowledge which one has of oneself at that stage of one’s enquiry,” and not on “an order corresponding to the actual truth of the matter.” As he puts it in the Fourth Set of Replies:

had I not been looking for greater than ordinary certainty, I should have been content to have shown in the Second Meditation that the mind can be understood as a subsisting thing despite the fact that nothing belonging to the body is attributed to it, and that, conversely, the body can be understood as a subsisting thing despite the fact that nothing belonging to the mind is attributed to it (AT VII 226),

and he continues: “I should have added nothing more in order to demonstrate that there is a real distinction between mind and body.” But given that he was looking for greater than ordinary certainty, and given his method of enquiry, contrary to what Gassendi thinks or misunderstands, he could not make any judgments about things which were unknown to him, namely, about the status of body. The rigour of his method, the unfolding order of the reasoning, demands that he make judgments only about things which are known to him, not about what he does not understand, is ignorant of, or doubts (see AT VII 27 and AT VII 357). That is the reason for saying that everything that he argues in the “Third, Fourth, and Fifth Meditations contributes to the conclusion that there is a real distinction between mind and body, which [he] finally established in the Sixth Meditation” (AT VII 226).

Arnauld does, in fact, concede that, as far as he can gather, “the author does attempt a proof of the claim in the Sixth Meditation” (AT VII 199), but he insists that the arguments found not only in the Sixth Meditation but also “anywhere in the entire work” (AT VII 201) are inadequate for establishing the incorporeality of the mind-which is the heart of Descartes’ dualism. This is perhaps the most controversial objection, but one that falls outside the scope and task of this paper.

The second part of my central task is to examine whether the Discourse argument is, as is standardly assumed, Descartes’ argument for dualism. As I argued in Section 2, dualism is concerned with metaphysical or essential distinctness (that is, real distinctness in kind), and depends on real distinctness ontologically-the latter is necessary but not sufficient for dualism. If the Discourse passage is to be correctly thought of as containing Descartes’ argument for dualism (or even one of his arguments for dualism), it must also contain an argument for ontological distinctness. The latter, however, can only be established (a) when two (or more) entities can be clearly and distinctly perceived as being apart, and (b) on the basis of “an order corresponding to the actual truth of the matter.” But the Discourse passage meets neither of these conditions, nor was it intended to. In it Descartes expressly states that he can clearly and distinctly perceive one entity while having reasons to doubt the other; furthermore, the premises and the conclusion are based on “an order corresponding to [his] own perceptions” and not “to the actual truth of the matter.” There is nothing to indicate therefore that a real distinction is, or is intended to be, established in the Discourse passage. But given that such a distinction is a necessary condition for dualism, it follows that the Discourse argument is not, and was not intended to be, an argument for dualism. I expand on all this in Section 5 below, where I provide further support for my critique of the standard claim.

The upshot so far is this: first, we cannot ignore the distinctions that are central to understanding the Discourse argument, nor can we ignore the order of reasoning, the order of the analytic method. Secondly, the argument is not an argument from doubt, but from clear understanding of what can or cannot be doubted. And thirdly, it is an argument based on an order corresponding to his own perceptions-it is an epistemological argument. It is, therefore, immune to the accusation of fallacy. Finally, the argument does not, and was not intended to, establish dualism. Both Arnauld and the standard-claim defenders who follow his misinterpretation of the Discourse argument, miss the subtlety, rigour, and direction of Descartes’ reasoning; they think that he follows “the order of the subject-matter, not the order of reasoning” (AT III 266-7), and therefore mistakenly assume that in a single place he draws conclusions about everything relevant to a given subject. But the method of following the “order of the subject-matter is good only for those whose reasoning is disjointed, and who can say as much about one difficulty as about another” (AT III 266-7).

4. The Substantiality Objection

A rebuttal of the standard claim is by no means the end to objections against the Discourse passage. One might still question Descartes’ conception of himself as a substance and maintain that such a conception is unsupported. In addressing this objection, I begin by saying that at this stage of his enquiry the meditator is at least certain that while he is thinking he is not nothing, he is something. As Descartes says: “I noticed that while I was trying thus to think everything false, it was necessary that I, who was thinking this, was something” (Discourse, AT VI 32). The meditator is certain that he exists while he is thinking, and this implies that he has at least a conception of himself as something real, the determinate nature of which will be (objectively) established progressively through the metaphysical arguments.

To support Descartes’ conception of himself as a substance, an elucidation of his notion of substance is required; for present purposes, it will be sufficient to draw on his discussion in the Principles, and in the Arguments appended to the Second Set of Replies. I start with a general definition in the Principles: “By `substance’ we can understand nothing other than a thing which exists in such a way as to depend on no other thing for its existence” (Principles pt.I, (sec)51). In this sense, he argues, there is only one substance, namely God; “the term ‘substance’ does not apply univocally […] to God and to other things” (loc. cit.) However, he distinguishes between this genuine (infinite) substance and finite substances, that is, “substances in the secondary sense.” A finite substance is that which can exist only with the concurrence of God (loc. cit.); in this sense “the term ‘substance’ applies univocally to mind and to body” (op. cit. (sec)52). In the Arguments, the notion of substance is as the subject of properties or attributes. Definition V: “Substance. This term applies to every thing in which whatever we perceive immediately resides, as in a subject [… By `whatever we perceive’ is meant any property, quality or attribute of which we have a real idea […] and a real attribute cannot belong to nothing” (AT VII 161).

The pressing question is: how can Descartes claim that he has a conception of himself as a substance? The reply is as follows: (i) nothing has no properties or attributes; (ii) if there are properties or attributes there must be something (a substance) to which they belong; (iii) I clearly and distinctly perceive the attribute of thought as an attribute that cannot be doubted while I am thinking or doubting; hence (iv) I am able to assert that there must be something, a res or substance, to which that attribute belongs.

What are the grounds for the premises of this reply? (i) is a metaphysical principle, or common notion: “nothingness possesses no attributes, that is to say, no properties or qualities” (Principles pt.I, (sec)52; see also Section 5 below). (ii) follows from the metaphysical categories of substance, attribute, and mode, and their asymmetrical relations of dependence, their conceptual distinction, and their modal distinction (see Sections 5 and 6). The distinction between substance and attribute is a distinction of reason or a conceptual distinction, not a real distinction (Principles pt.I, (sec)(sec)52; see also Section 5 below); the relation of dependence between attribute and substance is not a causal but an essential relation. If there are attributes, then there must be substances to which they belong; this does not yet tell us whether there are attributes or substances. However, “if we perceive the presence of some attribute, we can infer that there must also be present an existing thing, or substance to which it may be attributed” (loc. cit., italics added), but such an inference is not to some unspecified substance or bare substratum, nor is such a perception a sensory one; it is a perception of reason. I pursue the point by considering the presence of the attribute of thought which cannot be denied without a contradiction, and hence allows the inference to there being a substance to which it belongs. (iii) implies that one can clearly understand that one cannot doubt that one is thinking, because doubting is another kind of thinking-hence, by (ii), one can clear and distinctly perceive that the attribute of thought is present and cannot be doubted while one is thinking. Then (iv) validly concludes that one can be certain from the fact that one is thinking that there must be something, a res or substance to which the attribute of thought belongs and from which it cannot be separated; the commitment is no stronger than what belongs to the knowledge that one has of oneself. It is on the basis of this transcendental argument that the meditator at that stage of his enquiry can claim that he is something; he calls this res or substance ‘I.’

Those who do not follow the order of Descartes’ reasoning might still object that by saying that he has a conception of himself as a substance Descartes is claiming more than he is entitled to-he is making claims about what is objectively the case, something that can be grasped only from an objective standpoint and not from the first-person point of view of the meditator. Put differently, he is assuming that everything that he needs to know about what is objectively the case, when he raises the question “What am I?” is written on the face of cogito, ergo sum. The issues run deep here, but the core of the objection seems to be a confusion between epistemological and ontological questions– between what belongs to the knowledge that he has of himself at that stage and the actual truth of the matter. The fact that the thinker from his first-person point of view cannot deny without existential inconsistency that he exists, that he cannot deny without absurdity that the attribute of thought is inseparable from him while he is thinking, that if he can clearly and distinctly perceive the presence of the attribute of thought there must be something to which it belongs, and that the distinction between an attribute and the thing to which it belongs is a distinction of reason and not a real distinction, none of this entails that such truths cannot be grasped from an objective standpoint, but not in any sense that would give comfort to an adherent of the physicalist conception of the mind. Nor does it entail that the thinker is seeking to generalise from the first person (from “What am I?”) to what is objectively the case (to “what we are”). It entails only that the thinker from his first-person point of view can and does assent to the objective possibility of such truths. There is nothing in the meditator’s conception of himself, and in his conception of the objective world (even at this stage of his enquiry) that does not conform to what Gareth Evans suggests: namely, that just as one’s first-person thoughts require the intelligibility of a link with one’s conception of the objective world, so one’s objective conception of the world requires the intelligibility of a link with one’s first-person conception. Whatever the actual truth of the matter is, the intelligibility or objective possibility of such links are part of the meditator’s clear and distinct conception. Furthermore, whatever the actual truth of the matter is, ‘I’ picks out an undeniably real subject. As Descartes declares: “let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something; or make it true at some future time that I have never existed, since it is now true that I exist” (AT VII 36). To put this insight in modern terms, the cogito reveals the self-reference of ‘I’ (unlike that of any other indexical, demonstrative, or proper name) to be unshakable, requiring no criteria of identity, and makes vivid the fact that the continuity of the thinker involves “no keeping track of the object.” Such reference is identification-free; it is immune to error through misidentification.

Descartes’ argument is certainly not directly about the nature of self- consciousness, much less about the nature of self-consciousness as self-contained, or as isolated from, or as having its content independently of the objective world (as, for example,John McDowell claims). Even at the stage of his enquiry where his judgments are based on an order corresponding to the clear and distinct conception of what belongs to the knowledge that he has of himself, and not to the actual truth of the matter, such considerations are neither part of his commitments, nor do they follow from his arguments.

5. The Real Distinction Objection

To strengthen my critique of the standard claim, in what follows I focus on the question of Descartes’ real distinction, attending initially to some elucidatory remarks, and offering nothing stronger than a framework for a future plausible defence. Descartes’ definition is that a real distinction is a distinction between two or more substances or complete things when each of them can be clearly and distinctly understood apart from the others; “we can perceive that two substances are really distinct simply from the fact that we can clearly and distinctly understand one apart from the other” (Principles pt.1 (sec)(sec)60). The notion of apartness is central to a real distinction: X and Y are “really distinct when each of them can exist apart from the other” (df.X AT VII 162). His criterion for a real distinction is that, if we can clearly and distinctly understand X apart from Y, then that is sufficient for the recognition that they are really distinct-that is, separable (see AT VII 132). In Section 2 above I said that a real distinction has primarily to do with ontological or numerical distinctness, or separability, and not with metaphysical distinctness. I now offer two reasons in support for such a diagnosis. First, it is clear that neither his definition of nor his criterion for a real distinction is directly about dualism, which is a metaphysical thesis concerning distinctness in kind. Secondly, it is consistent with his definition of and criterion for a real distinction that two or more mental substances, for example, are really distinct since they can exist apart, but it does not follow that they are metaphysically distinct. Ontological distinctness does not entail metaphysical distinctness, though it provides the basis for it.

In the Sixth Meditation (AT VII 78), Descartes’ argument for the Real Distinction presents an account of ontological distinctness-that is, of things that can be clearly and distinctly understood apart from one another. The argument does not and was not intended to prove that things that can be understood apart exist in separation, but to demonstrate that they are ontologically or numerically separable, and hence that they can exist in separation-a logical possibility. Real distinction is neither extensionally nor intensionally equivalent to actual separation. The important difference between real distinction and actual separation has been misconceived by many of his critics, both at the time and in the present-a misconception that has led to the mistaken view that for Descartes a person is a disembodied ego. Indeed, in a recent book in the philosophy of mind the authors claim that the key to the problem with Descartes’ dualism is the neglect of the body and the artificial conception of the mental that separates it from our embodied involvement with the world. A response to such misconceptions and misunderstandings can be found in what Descartes actually argues: that a human being, or a person is a substantial union of mind and body (see, for example, AT VII 56 passim, and AT VII 228). (Nor, incidentally, does the argument depend upon proving the existence of God. Our knowledge “that two things are really distinct is not affected by the nature of the power that separates them” [AT VII 170; see also Principles pt.I (sec)(sec)60 quoted above, and AT VII 78]).

The argument for dualism or metaphysical distinctness, which is embedded in and dependent on the argument for ontological distinctness, is an argument from real essences. It is not only an argument from the clear and distinct understanding that complete things or substances are separable; it is also an argument from the clear and distinct understanding of attributes, and an attribute is what constitutes the nature or essence of a substance; it is what can be asserted of a substance when we are clearly and distinctly conceiving it in a general way. (Principles, pt.I ^sub 5^(sec)(sec)56; see also Second Set of Replies AT VII 162, df.IX) An attribute is not a property in any ordinary sense of the term, but what constitutes the very nature of a substance, without which it would not be what it is, and without which we would be unable to single it out and refer to it. Clearly and distinctly conceiving a substance, or knowing which substance it is, cannot leave the question entirely open as to what kind it is; these are the requirements of reference and singling out based on a clear and distinct conception. What is being singled out by Descartes’ arguments as an object of reference and understanding is not a bare this or that, not a bare substratum. We cannot suppose that we can understand which substance it is by conceiving it as having no attributes without making such a conception impossible.

At the heart of the argument for dualism lies the word quatenus, or in so far as, which Descartes uses precisely in order to show that he is not making claims that are stronger than he intended. By means of that word he tries to capture what can be said in the strict sense only. “[O]n the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing” (AT VII 78, italics added). Dualism demonstrates the metaphysical or essential distinctness of mind and body (the incorporeality of mind and the extensionality of body), not their actual or ontological separation.

Cottingham provides what he calls a “charitable interpretation” of some of the issues I discuss in this paper, but presses the following objection:

my ability clearly to perceive X apart from Y (e.g. mind apart from body) cannot, since my intellect is limited, rule out the possibility that there is a chain of necessary connections, unperceived by me, which would reveal that Y is after all essential to X.

If by ‘necessary’ Cottingham means `physically, or causally necessary,’ then Descartes does not deny that there are causal connections between mind and body, but it does not follow from this that “Y [body] is after all essential to X [mind]” (assuming that ‘essential’ here means metaphysically essential), nor does it follow that Y and X are identical. What does follow is that, although mind and body are metaphysically distinct, as a matter of contingent fact they are, as Descartes puts it, intimately connected and do not, as a matter of fact, exist in separation-they form a substantial union, what Descartes calls a person. If, on the other hand, by ‘necessary’ Cottingham means `logically, or metaphysically necessary,’ then it would be impossible to have a clear and distinct perception of X apart from Y. We should not think that what is being clearly and distinctly perceived here is X, and that the phrase `apart from Y’ is a description of the nature of that perception. Rather, what is clearly and distinctly perceived is `the apartness of X from Y,’ and such a perception has nothing to do with ignorance or epistemic limitations, nor does it leave room for doubt that they are apart. Nor should we think that a real distinction is a distinction between clear and distinct perceptions; it is a distinction between entities that can be clearly and distinctly perceived apart from one another. Apartness does not mean clearly and distinctly perceiving one entity while having reasons to doubt the other, or without being aware of the other; “the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct” (AT VII 78).

The crux of the controversy, however, lies in the question: why is that enough? We should not lose sight of two important points here: first, clear and distinct perceptions cannot be contradicted; they are based, not on what one is not aware or is ignorant of, but on understanding. Secondly, it is the essential nature or necessity of things which constrains one’s clear and distinct perceptions-not the other way round. Thus if two things can be clearly and distinctly perceived apart, they cannot be essentially connected; conceiving them apart corresponds to the fact that “they are capable of being separated” (AT VII 78).

Of course, one can have a clear and distinct perception of X while having reason to doubt Y, but no real distinction is drawn by Descartes on this basis, no conclusion is drawn concerning their apartness-the status of Y is left undecided in the Second Meditation, the Discourse passage, and similar passages elsewhere. One can also have a clear and distinct perception that X is thus-and-so without being aware of some (other essential) property of it, some F-ness; but again, it does not follow that X can be clearly and distinctly perceived apart from F-ness, or F-ness apart from X, nor is it intelligible that F-ness should be denied of X simply because one is not aware of F-ness. Arnauld takes ‘deny’ to mean the same as `not being aware of or as `as having reason to doubt’ (see AT VII 202).

Descartes makes it clear that it is logically possible that “we can clearly and distinctly understand that a triangle in a semi-circle is right-angled without being aware that the square on the hypotenuse is equal to the squares on the other two sides” (AT VII 224-5), but it is not intelligible that the Pythagorean property should be denied of it. (AT VII 227) However, the converse is logically impossible: “we cannot have a clear understanding of a triangle having the [Pythagorean property] without at the same time being aware that it is right-angled” (loc. cit.). Furthermore, neither the triangle apart from the Pythagorean property nor the Pythagorean property apart from the triangle can be understood as a complete thing. A right-angled triangle is a complete thing, but the Pythagorean property is one of its (essential) properties, not a complete thing. Given that it is impossible to have a clear and distinct perception of a right-angled triangle apart from its Pythagorean property, or the Pythagorean property apart from a right-angled triangle, the relation between them is essential, and the distinction between them is conceptual or a distinction of reason, not a real distinction. Such an impossibility has nothing to do with our limited epistemic state or ignorance concerning the Pythagorean theorem.

By parity of reasoning, if the mind were not a res or substance but an essential property of body, then it would be logically impossible to clearly and distinctly perceive the mind-property apart from body, just as it is logically impossible to clearly and distinctly perceive the Pythagorean property apart from a right-angled triangle. Yet, in the case of “X and Y (mind and body)” this is not true; there is no logical impossibility at all, once we have reached the Sixth Meditation: “we can clearly and distinctly perceive the mind apart from body”; the mind can be clearly and distinctly understood as a complete thing and “includes nothing at all which belongs to the body,” and the body can be clearly and distinctly understood as a complete thing and “includes nothing at all which belongs to the mind” (AT VII 225). All the properties “which belong to body can be denied of the mind” (AT VII 227) without a contradiction once we have a clear and distinct perception of mind apart from body, but such a denial was logically impossible in the case of the triangle and its properties. In the case of mind and body, their apartness is logically possible (and that is all Descartes’ argument needs in order to go through), even if as a matter of contingent fact they do not exist in separation (and that is all his commitment amounts to). What can be drawn from these elucidatory remarks is that a real distinction is established only when both entities are clearly and distinctly conceived apart as complete things.

6. The Triviality Objection

At this juncture it might be objected that one’s certainty of having a clear and distinct conception of X apart from Y requires prior knowledge of something like the real distinction, the implication being that the argument turns out to be trivially true. In the Third Set of Objections and Replies, Descartes argues thus: we do not come to know a substance immediately, through being aware of the substance itself-, we come to know it only through its being the subject of certain acts. Hence it is perfectly reasonable, and indeed sanctioned by usage, for us to use different names for substances which we recognise as being the subjects of quite different acts or accidents. And it is reasonable for us to leave until later the examination of whether these different names signify different things or one and the same thing. (AT VII 176)

But, he goes on, “once we have formed two distinct concepts of these two substances” we can establish “whether they are one and the same or different” (AT VII 176). In his reply to Arnauld, Descartes argues:

a real distinction cannot be inferred from the fact that one thing is conceived apart from another by an abstraction of the intellect which conceives the thing inadequately. It can be inferred only if we understand one thing apart from another completely, or as a complete thing. (AT VII 220)

A real distinction is not inferred by an abstraction of the intellect which conceives one thing inadequately. In passages like those in the Discourse and the Second Meditation, where Descartes can clearly and distinctly conceive one entity while having reason to doubt the other, no distinction drawn leads to ontological or metaphysical conclusions, but only to epistemological considerations. Any move from such epistemological considerations to the real distinction is mediated by many and complex arguments, including the argument of conceiving both entities clearly and distinctly. It is only then that the meditator can move away from the epistemological arguments to the metaphysical arguments and finally establish both ontological and metaphysical distinctness on “an order corresponding to the actual truth of the matter.” The meditator then knows “the fundamental ground of difference” essential to X and to Y. But in knowing this, it is not the intellect that imposes any de re necessity on things, nor is it the intellect that makes it thus and so; it is the necessity or the essential nature of things which determines one’s thinking. As Williams explains, to understand Descartes’ argument we should not

define ‘essence’ as a particular informative and distinctive sub-set of a thing’s necessary properties; [rather] a thing’s necessary properties are to be understood as its essence and properties entailed by its essence. Essence for Descartes is a primary notion.

The direction of reasoning based on clear and distinct conception is not from our definitions, or conceptual schemes, or usage of names, to the non– identifiability of the mind with matter. It is the non-identifiability of mind with matter-the essential nature of the mind insofar as it is simply a thinking thing, and the essential nature of body insofar as it is simply an extended thing-which determines our clear and distinct conceptions and the correct signification of the names we use. Our definitions, or usage, or conceptual schemes are a consequence of the non-identifiability and irreducibility of the mind. If it were the usage of names that determined the nature of substance, then there would be no point in saying “it is reasonable for us to leave until later the examination of whether these names signify different things or one and the same thing” (AT VII 176). On this conception, the mind’s non– identifiability and irreducibility are the source, not a trivial consequence, of our definitions and conceptual schemes. A clear understanding of the direction of reasoning makes it hard to see how any of this trivialises the argument for the real distinction.

7. Conclusion

There is a lot of unfinished business. Perhaps the most challenging objection is that Descartes has not managed to provide even a plausible defence of dualism or the incorporeality thesis of the mind; this, however, was far from my intention to discuss, let alone to try to settle here. The issues are complex and difficult, but my arguments direct one towards a framework within which a prolegomenon to any future metaphysics of mind can be developed (and such a metaphysics is genuinely needed), and within which the incorporeality thesis can be addressed; explicitly, they show that Descartes’ arguments are more rigorous and watertight than many of his critics both in his own time and at present have generally recognised. At the heart of Descartes’ metaphysics is the all-important and recalcitrant philosophical question concerning the mind’s place in the world. The ultimate answer remains to be found. In the context of the central task of this paper, however, the corrections I have made to the misconceptions of both Arnauld’s fallacy objection and the standard claim against the Discourse passage are substantial and conclusive, and demonstrate that if philosophers wish to reject Descartes’ dualism they cannot reject it on the basis of the standard claim.

[S]eeing that [philosophy] has been cultivated for many centuries by the most excellent minds and yet there is still no point in it which is not disputed and hence doubtful, I was not so presumptuous as to hope to achieve any more in it than others had done. (Descartes [AT VI 9])