Following Descartes but in the opposite direction:

I exist. Something has made the assertion in the previous sentence and must have thought it to do so. Therefore my thoughts exist.

Combining with the direction established by Descartes I have cogitosum. Since assuming either is equiavlent to assuming the other I conclude that Descartes does not establish existence as following from something more basic or fundamental. Instead he has merely stated a tautology.

Am I right or wrong? Or both, or neither?

  • 3
    "I exist, therefore something has made the assertion" is fallacious. Existence needs nobody's assertion of it. The inference is made from the act of assertion, which is not contained in "I exist". Otherwise, what is to be inferred is already assumed. Descartes's direction is also fallacious, see Could 'cogito ergo sum' possibly be false? But biconditionals need not be "tautological", many non-trivial theorems of mathematics have this form.
    – Conifold
    Commented Aug 24, 2019 at 6:50
  • Does a rock think it exists? Well maybe, but it lacks the apparatus to communicate (with us), as such rocks cannot manifest their thoughts in a way that would convince us they exist. So the question becomes do believe that thoughts are immanent to all matter? Or do you believe that a certain level of structural complexity is needed to sustain thinking? The latter case would of course only allow for Descartes' "direction".
    – christo183
    Commented Aug 24, 2019 at 9:58
  • I second the Servaes' motion. And the conditional is NOT the same as the biconditional to be sure.
    – J D
    Commented Aug 24, 2019 at 18:07
  • @conifold...actually "existence" is an assumption as it is an undefined context. We assume reality through the senses, and we assume the senses to see if we can connect one assumption to another with this connection further assuming a truth value. "I" is a point of awareness and as such is assumed. The fact that "I" is ground zero of consciousness for the individual necessitates itself as both assuming and assuming. With all assumptions being void, self reflection is thus the negation of negation or voiding of void.
    – Eodnhoj7
    Commented Aug 30, 2019 at 7:30
  • @christo...the same minerals which form the rock form the observer, we are left with subsets within subsets of identity.
    – Eodnhoj7
    Commented Aug 30, 2019 at 7:31

6 Answers 6


Does thinking imply existing? Descartes argues yes: it is impossible for anything to think which does not exist.

Does existing imply thinking? Most people would say no. Most would say that a rock exists, and the rock does not think. Therefore it is possible for something to exist which doesn't think.

As such, the basic claim doesn't go both ways.

Meanwhile, your formulation wasn't quite what you described in the explanation. You should instead have said something like "I claim to exist. Therefore I think." That one is more defensible, depending on the exact definition of the verb "to claim." (Of course that is also not reversible: it is possible to think and just never say "I exist.")

Now, let us suppose instead that the statements, without any additional premises, did imply one another. Does that mean that Descartes was just stating a tautology? The simple answer is no, because he did not follow it round in a circle.

Suppose someone says "Alice is my daughter, therefore I am her parent." Similarly they could say "I am Alice's parent, therefore she is my daughter." If they said nothing else, that would be an unsupported circle (although not a tautology; being a tautology would require that it be impossible to not have a daughter called Alice)

However if they start with "I gave birth to Alice and remember it well!" then they can justify the other statements.

Similarly even if Descartes did hold that existing implies thinking, as long as his reason for saying "I think" is not "I exist" then he can use it as a premise.


Perhaps what would work is cogito ⇔ cogito sum, that is, "I think if and only if I think I am". Although someone who thinks may not think of asking themselves whether they are or not, if someone asked them whether they were or not I imagine they would not deny that they are.

Having a biconditional is not what makes a tautology. All one needs is a proposition that is always true regardless of the truth values of the component, atomic propositions. For example, let C be "I think" and S be "I am" then "C → S" is "I think therefore I am". The following is a tautology that is not a biconditional and it seems to represent the idea behind Descartes' idea:

I think, and since my thinking implies that I am, therefore I am.

Or symbolically, (C ∧ (C → S)) → S. To see that this is a tautology, even though it is not a biconditional, consider the following truth table:

enter image description here

Note that for all true-false valuations of the atomic propositions,C and S, the proposition being considered is true.

Michael Rieppel, Truth Table Generator. https://mrieppel.net/prog/truthtable.html

  • (P=P)=(-P=-P) works on the truth table. P if and only if (-P=-P) works as well because it requires expression through the law of identity. The same applies for -P if and only if (-P=-P), but this does not work. Even then the statement of (P=P)=(-P=-P) necessitates that considering both P and -P are subject to the law of identity, we are observing a contradiction in form. P=/-P can be expressed as (P=P)=/(-P=-P) as each variable is subject to the law of identity...but the calculator says (P=P)=(-P=-P). The calculator is to limited and cannot deal with advanced recurssion problems.
    – Eodnhoj7
    Commented Aug 31, 2019 at 21:07

If you say "I exist", then you are thinking. It is that thinking that makes you sure you exist. That was Descartes point. Changing the order of the words of his thoughts doesn't make your thoughts any less thought-ish.


Do you think while asleep? Or under general anesthetics? If not, do you cease to exist? If you cease to exist, how come something happened to you during that operation?

So logically, your definition of "thinking" apparently includes whatever happens in those states, because you assume continuity of being (otherwise things get really complicated). So your "thinking" does not require consciousness, which is a contradiction.

The reverse argument by Descartes does not have this problem. It does not make an assumption about the state of being under the condition of non-thinking. It is flexible enough to grant existence to non-thinking entities as well, or at least the possibility of existence.

"the fact that I think proves that I exist" does not create a contradiction when any of its terms are reversed.

"the fact that I exist proves that I think" does, because while this does describe the normal state, there are states of existence, even for you, where no common use of the work "think" applies.


"I think; therefore I am".

According to the trillema fallacies (Munchauseen, Fries, Agrippa, Albert) "I" is the point of awareness in which we assume reality.


It is a self referential statement where self referentiality necessitates creation of multiple contexts of "I". The self looking on the self observes multiple selves where the I progresses to another I.

This can be observed where "I" think is one context of self referencing:


And "I am" is another context of "I".


Each I, as a point of awareness (using Sextus Empiricus version of the trillema (all things change as there relations change)), effectively is the I viewing itself from different angles.

It is creating itself through the recurssion of contexts:

(I --> I) <--> ((T)-->(A))

In one respect "thinking" is a context of "modality" the "I" exists through.

In another respect "am" follows the same course.

Each modal state, where "think" and "am" are both very general modes, effectively is a sub context of I itself, thus is an extension of "I".

With each new context I exist in comes a new progressive I, with I being purely assumed as a point of assumption and the following contexts following the same course.

The repetition of these assumptions forms a tautology that can neither be proven or disproven. So yes you are right. But where Descartr fails is his ability to point out "I" is assumed, thus the contexts stemming from "I" are also assumed.

The pyrhonists (western variation of the buddhist, see wiki page) observe this.

Existence thus is grounded, through the I, as the recursion and isomorphism of assumptions.

Isomorphism is the inversion of one context:


Into a symmetrical opposite state (ie many contexts)


Which again inverts


Thus one assumption, "I" is an empty context which is defined by its continual progression to further contexts that as assumptions through the original assumption are inherently "void".

This inversion of one to many requires recursion and with recurssion necessitating isomorphism. It's a loop, showing the nature of assumption as fundamentally "void" negating itself into "form".

Wittgenstein "tautology of tautology" statement, most every philosopher is loosely aware of, is a variation of descartes because of these principles alone.

This recursion/isomorphism is also observed in Euclid's first postulate of a line as the distance between two points. One point, inverts to another point (many points) and the recursion is defined through the line as a Directional quality. One "I" is directed towards itself resulting in two "I".

This connection of the "I", as the most base of assumptions, is the first act of definition in thought. Thought is thus the projection and connection of assumptions that have a recursive nature expressed through "the line".

One assumption individuates (divides/multipies simultaneously) into another assumption and this always occurs through recurssion thus necessitating the basic "line" as the objective form or subjective understanding.

Thus self reflection is grounded in spatial axioms, where Platos Justified True Belief as an expression of the forms, is really the objectification of the subjective nature of space that kant observes.

In these respects Descartes claim of "I think therefore I am" is really Justified True Belief from a seperate angle of awareness. With belief being the assumption of I, "thinking" as the justification through definition observed by the first recursion of the I, and "Am" observing the "thought of thought" as a "dualism of dualism" of "I".

Fundamentally "I think therefore I am" observes 4 different points of view based upon the recursion argument presented above. This corresponds with the "axiom of maria" (Google this because I want you to research it) Jung promotes inherent within the process of individuation.

This process of individuation is what Descarte is actually philosophizing about and presents roots for young.

I(X)=I(Y) still necessitates as base I=I that is rooted in aristotelian identity properties. Thus descartes statement, while a tautology has aristotelian roots and the act of self reflection takes on a form of "self measurement".

This self measurement, with measurement being the foundational meaning for the Greek "arithmetica", is fundamentally mathematical in nature. Math being the quantification of reality through the individuation of reality, we all reality being assumed fundamentally through the "I" as void in it's own context.

The I is fundamentally assumed, and as assumed it is void in such a manner it is no different than a dot considering the most apriori observation that exists is the Dot as "self". It is a universal symbol among all cultures...why if not apriori?

How is this different than the "I" directed towards itself under a self assumption considering the subjective nature of space according to Kant?

Even time as subjective, is observed through Heideggers conception of Time, as universally expressed by two points and a line (thus necessitating Euclid's first postulate as the grounding of what we understand as finite).

Thus "thought" as the first context the "I" is created through, by descarte", is the creation of definition where the I as subjective is fundamentally finite and subject to it's own perception of time which stems from itself.

Self reflection thus requires an inherent subjective state of time and space as each I is a point of awareness that occurs by recurssion

Considering Kant's premise of space being primarily subjective, euclids first postulate is descartes axiom given a platonic form. But this platonic form of the line is merely the objective viewing of how the subjective operates.

Even Jung's process of individuation, expressed in Descartes "I...therefore I", necessitates a form of evolution that is protectively linear in nature. This is further reflected in aristotelian actuality and potentiality, where being takes form (ie "volume") through the dynamic movement of formless potentiality (ie mass).

Thus "I" actualizes through the "thought" descarte observes, where the "I" as previously "void" or "formless potential" exists through a basic recursive self measurement embodied under the "line" as a universal form for the subjective connection and seperation of assumptions.

Thus we can see how "I think therefore I am" can be viewed as the evolution of assumption through a multigenerational recurssion and isomorphisms of "I's" that stem from prior to Euclid all the way to the present.

"I" thus can be implied as a Jungian Zietgeist under certain respects.

So descarte, as the premise point you are observing, can actually be viewed as given definition to the nature of consciousness and how we assume through basic recursion and isomorphism.

Hofstastder's book: "Godel, Escher and Bach" and "I am a strange loop" explores this nature of isomorphism, recurssion from another angle as well.

So this should help in viewing Descarte from different perspective "I"'s by observing it through different philosophers.

I may have to clarify some points...and ignore the typos from the ipad.

  • 2
    Instead of just saying "wiki" (there are many wiki's) try linking as in the example. Imagine your readers' time to be more valuable that your own: they will appreciate that.
    – christo183
    Commented Aug 31, 2019 at 7:14
  • No disagreement, on iPad and copy and paste option doesn't work as well. Need to "link" alot more than the above.
    – Eodnhoj7
    Commented Aug 31, 2019 at 16:23

I would like to offer a more radical proposal as possible answer.

Argument can also be phrased as:

I know I exist (cogito), therefore I must necessarily exist (sum).

Think (cogito) in the argument is usually taken to be very human-centric, so in very narrow interpretations nor even other mammals can be aware of their existence.

However in a broad sense of being aware of existence in a very basic form (not human-centric necessarily), the following can be said:

There is an equivalence between existence and being aware of this existence. Can there really be existence without being aware of this existence? What would that mean for existence?

For example, why do humans have consciousness anyway, why is it needed? According to some more or less popular views, eveything would be the same without it (or would it?).

Or what would mean for existence of the world prior to the appearence of what are recognised as conscious beings (whatever one would like to include in this category), did the world exist or not, and if so how was this established?

According to the view stated here, Descartes' (and others') statement is only half the story of the basic equivalence between existence and how this very existence is indeed (self-)verified (ie awareness of existence). One needs the other.

Note this basic awareness of existence does not seem to cease when asleep, dreaming or in altered states of consciousness.

I will leave it here for further thought.

For an elaboration upon this point of view, see for example:

Realistic Monism: Why Physicalism Entails Panpsychism, by Galen Strawson

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