He says, that he cannot think that he is thinking while actually not thinking. So, the fact that he thinks that he is thinking already guarantees that he thinks.

But what kind of thinking is it? Does it mean that any passing thought involves thinking? Cause actually I can think (imagine) that I think about something while actually not thinking about that thing. For example, I don't think about being religious person or even religion itself but I can think that at some point of my life I might think about religion or imagine myself as thinking about religion while actually I am not thinking about it.

Or this thinking is about self-reflection rather than thinking exactly about some topic?

  • "He says, that he cannot think that he is thinking while actually not thinking" ? See Principia, art 7 "That we cannot doubt of our existence while we doubt, and that this is the first knowledge we acquire when we philosophize in order. While we thus reject all of which we can entertain the smallest doubt, and even imagine that it is false, we easily indeed suppose that there is neither God, nor sky, nor bodies, and that we ourselves even have neither hands nor feet, nor, finally, a body; but we cannot in the same way suppose that we are not while we doubt of the truth of these things; Jan 19, 2019 at 19:09
  • for there is a repugnance in conceiving that what thinks does not exist at the very time when it thinks. Accordingly, the knowledge, I THINK, THEREFORE I AM, is the first and most certain that occurs to one who philosophizes orderly." Jan 19, 2019 at 19:09
  • He essentially means 'cognition' not 'thought'. That is.. if your brain is working and you are wordlessly enjoying the beauty of a leaf.. or fastening buttons.. you are 'thinking'. In other words. He doesn't mean 'pondering'.
    – Richard
    Jan 20, 2019 at 0:52

4 Answers 4


See Descartes' Theory of Ideas : Ideas Understood as Modes of Thinking :

According to Descartes’ ontology there are substances, attributes, and modes. These are understood relative to one another, in terms of ontological dependence. Modes depend on attributes, and attributes depend on substances. The dependence relation is transitive; thus, modes depend ultimately on substances. No substances, no modes.

A mode of some thing was understood by Descartes as a a way of being that thing.

The nature of a mind, Descartes says, is to think. If a thing does not think, it is not a mind. In terms of his ontology, the mind is an existing (finite) substance, and thought or thinking is its attribute. Insofar as the nature of a mind is to think, where thought is the mind’s defining feature, Descartes calls it the mind’s principal attribute.

See Principia Philosophiæ (1644) :

art.53 That of every substance there is one principal attribute, as thinking of the mind, extension of the body.


Thinking, for Descartes, is just consciousness, in the widest sense of the term. In an act of thinking, of consciousness, we can distinguish between (1) the act, and (2) the content of the act, what the act is about. An act is an event in time. A content is an object in the most general sense, which may be abstract, like a mathematical theorem, or imaginary, like Donald Duck. If, for example, I was thinking about the moon yesterday, and I am thinking about the moon again today, those are two acts with the same, single content.

Descartes's argument relies of an occurrance of an act of thinking, of consciousness. It does not matter, for Descartes's argument, what the act is exactly about. It does not matter, that is, what is the content of the act. So if I imagine that I am thinking, I am certainly thinking, because imagining itself is a kind of act of thinking, of consciousness. And it doesn't matter, for the argument, what this act of thinking is exactly about.


Descartes on 'thought' - the puzzle

John Cottingham's analysis may help (John Cottingham, 'Descartes on `Thought'', The Philosophical Quarterly (1950-), Vol. 28, No. 112 (Jul., 1978), pp. 208-214) :

In a famous passage in the Second Meditation Descartes asks What am I then? A thing which thinks. What is that? A thing which doubts, understands, affirms, denies, wills, is unwilling, and also imagines and feels.

On the face of it, the gloss Descartes offers on 'a thing which thinks' (res cogitans) is quite extraordinary. Doubting and understanding are evidently kinds of thinking. But it is far from obvious that affirming, denying and willing are to be classified in this way. And as for 'feeling' (sentire), this is, in any normal sense, something entirely different from thinking. (Cottingham : 208.)

A false solution

A highly influential account of what is going on in the passage cited and other similar passages has been proposed, among others, by Alexandre Koyre:

The term 'thought'- pensée, cogitatio - had, in Descartes' time, a much wider meaning than it has now. It embraced not only 'thought' as it is now understood, but all mental acts and data: will, feeling, judgement, perceptions, and so on.

Taking a similar line, Elizabeth Anscombe and Peter Geach warn that "to use think and thought as the standard renderings for cogitare and penser and their derivatives gives Descartes' conception an intellectualistic cast that is not there in the original". Accordingly, they render res cogitans as 'conscious being', and frequently (though not always) use more general terms like 'experience' for Descartes' cogitatio. And indeed textbooks on Descartes routinely caution the student not to construe the term 'thought' in its normal, narrowly cognitive sense.

However, while it is clear that during and after Descartes' lifetime cogitare was widely used in this extended sense, it is quite possible that the principal force influencing such an extended usage was the Cartesian corpus itself. What is far from clear is that when Descartes first used cogitare and penser in this way he was simply following established usage. Despite Anscombe and Geach's claim that "cogitare and its derivatives had long been used in a very wide sense in philosophical Latin", the scholastic tradition makes a very clear distinction between the "cognitive" and "appetitive" parts of the mind-according to Aquinas: "duae sunt praecipue facultates . . . quarum altera est cognoscitiva, altera appetitiva". ['There are two main faculties, of which one is cognitive and the other appetitive' : GT.] So it is not at all clear that Aquinas and his disciples would have accepted it as self- evident that 'res cogitans' implied 'res volens'. Vith regard to Descartes' own contemporaries, we have the strongest possible evidence that Descartes' use of the term pensee/ cogitatio was initially puzzling and confusing. Mersenne wrote to Descartes in 1637 objecting that if the nature of man was simply to think, it would follow that he had no will. Descartes had to explain carefully in reply that he regarded willing, understanding, imagining and feeling as "various ways of thinking". (Cottingham : 208-9.)

A more illuminating approach

Step 1

Descartes' use of cogitatio then, was, if not downright innovative, at the very least somewhat curious. But there is something deeply unsatisfactory about simply leaving it there. When philosophers use central terms in an unusual way there is invariably an underlying philosophical rationale for it: compare 'perceive' in Berkeley, or 'pleasure' in J. S. Mill.

What I want to suggest is that the "intellectualistic" overtones of the terms cogitatio and pensée, so far from being misleading, or calling for special translation, are in an important sense meant to be there, for reasons which have their roots deep in Cartesian method and metaphysics. Let us start by going back to the context of our original quotation. Descartes asserts that he is a thinking thing. On what basis? Because the extremity of doubt-the malicious demon-failed to separate this attribute from his nature:

What am I now that I am supposing that there is some supremely powerful deceiver? . . . Thinking - here I find it - this alone cannot be torn from me.

Descartes' claim that 'thought' is inseparable from his nature is, like his discovery of the certainty of his own existence, inextricably bound up with a strictly cognitive process - the method of doubt: while it is easy to suppose there is no God, no heaven, no bodies . . . we cannot in the same way suppose that we who doubt these things are not.

Or again:

from the very fact that I thought of doubting the truth of other things it very certainly and evidently followed that I was. On the other hand, if I had ceased to think ... I should have no reason to suppose that I had existed. From that I knew I was a substance whose whole nature or essence consists in thinking.

The way in which 'cogito ergo sum' and 'sum res cogitans' are arrived at thus suggest a strictly intellectualistic interpretation of cogitare. Indeed, though it is sometimes claimed that "any conscious process will do as a premise for the cogito", this seems inconsistent with Descartes' method. "I want" is not indubitable in the sense in which "I think" or "I doubt" are. The demon could presumably deceive me into thinking I wanted an ice cream (though perhaps he could not deceive me about being aware of wanting one: I shall return to this point later). For the indubitability of "I think" consists precisely in the fact that doubting it entails its truth. So far, then, the "thinking being" of whose existence Descartes is apprised as his first step out of the morass of doubt is precisely that - a being that thinks, in the ordinary, strictly cognitive sense. (Cottingham : 209-10.)

Step 2

It is now time to look more closely at exactly what Descartes means by the frequent inclusion of sense-perception and sensation as "modes of thinking" (modi cogitandi). Perhaps the clearest indication of what is going on comes in Book I of the Principles, where Descartes discusses why 'video ergo sum' might not do equally as well as 'cogito ergo sum'. Descartes in effect says that 'I see' is ambiguous. If understood 'de visione' it is not a good premise for inferring one's existence (since, for one thing, it could then imply the existence of a body, which is subject to doubt). Alternatively, however, it may, says Descartes, be understood "concerning the actual sense or awareness of seeing" (de ipso sensu sive conscientia videndi); here it is quite certain "since it is in this case referred to the mind which alone feels or thinks it sees" (quia tune refertur ad mentem quae sola sentit sive cogitat se videre). Once again, in connection with Descartes' employment of cogitare, we are presented with the crucial term conscientia (self-awareness); and this makes it clear just how misleading it is to say tout court that cogitatio "includes" sensations and feelings. The only sense in which seeing is a true cogitatio is the sense in which it may involve reflective mental awareness - the self-conscious perception of the mind that it is aware of seeing.

The more one looks at what Descartes says about perceptual operations like seeing and hearing, as well as sensations like feeling pain, the more one observes that he regards them as having a curious hybrid nature. Descartes often calls perception (e.g., seeing) a "special mode of thinking"; and sensations (e.g., of heat) are frequently called "confused modes of thinking". The "special" nature or "confusedness" turns out to be tied up with this: that such operations qualify as cogitationes at all only in a partial and restricted sense. In a famous passage in the Sixth Meditation Descartes points out that when the body is damaged we do not merely notice the damage puro intellectu, as a pilot observes damage to his ship; in addition we actually feel pain, because of the mysterious "intermingling" of the mind with corporeal substance. What is seldom if ever asked about this much discussed passage is why Descartes should have put the matter in this way. Why should one ponder on the curious possibility of being aware of bodily damage in a purely cognitive way? Once one looks for a rationale behind Descartes' train of thought, the answer springs into focus: because that is exactly how one would expect it to be for a res cogitans. In a letter to Regius, Descartes discusses how an angel (a pure res cogitans) might experience if he were in a human body: he would not feel (sentire) as we do, but would merely "perceive the motions caused by external objects". This is because sensations such as pain are not the pure thoughts (purae cogitationes) of a mind distinct from a body, but are rather the "confused perceptions which result from the real union with the body". (Cottingham : 212-3.)


The attempt to understand cogito ergo sum commonly causes that problem: what is thinking? what is existence?. This is the key:

"Esse est percipi"

-- George Berkeley

This means that the object exists if a subject can perceive it. Berkeley's position is quite subjectivist, but in final terms, that's the final reason Descartes searched for a fundamental truth. Then, if existence is subjective, something exists for me if I can perceive it (personally, I prefer to express it as something exists for me if I can interact with it due to interaction implies a more factual, physical, not only ideal assessment of existence).

With cogito ergo sum, Descartes was looking for a fundamental truth, given that imaginable every postulate would be subject of doubt. Then, he addressed the problem of existence. What is existence? "space occupation"? No! Existence would imply sompething deeper, a perception! Then, what Descartes accepts as fundamental truth is that if I'm able to perceive myself, I do exist. As said, I would express it as if I'm able to interact with myself, I do exist. Thinking is precisely such perception or interaction. A friend of mine uses a simpler traduction on his philosophy lessons at the university: if I can think of myself, I do exist.

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