Home > Cogito ergo sum

1 Introduction

Having reached, at the end of the first meditation, what he considers to be the ultimate level of doubt—the evil demon —Descartes seeks one fact of which he can be certain. In the statement "cogito ergo sum", he finds two: that he is thinking and, following this, that he exists. This concept is stated at the start of the second meditation as follows:

"I convinced myself that there is nothing at all in the world, no sky, no earth, no minds, no bodies; is it not therefore also true that I do not exist? However, I certainly did exist, if I convinced my self of something. There is some unidentified deceiver, however, all powerful and cunning, who is dedicated to deceiving me constantly. Therefore it is indubitable that I also exist, if he deceives me…he will still never bring it about that I am nothing as long as I think I am something."

At this point Descartes claims to know that he exists due to the occurrence of any cognitive process, including doubt (this argument will hereafter be referred to as the cogito). Thought entails existence, being as it is the final point of any assertion (this is true both in terms of statements such as "I am thinking about a rose", which is true as long as I am; and also such statements as "I breathe, therefore I exist", which itself is only true if it can be reduced to thought). Of course, the framing of the question 'How does Descartes try to prove his existence?' is unhelpful here, for the matter of Descartes proving his own existence as an historical figure is entirely different from his proof of the existence of some 'I'. The process by which he moves from the latter to the former is complex, interesting, and contentious; this article will be limited to the nature of 'I' only as a by-product of my discussion of the internal structure of the cogito. Three arguments will be presented against the cogito, all of which will be rejected, before an examination of Bernard Williams' rejection of the cogito on the grounds of its third-person comprehensibility.

2 Success of the Cogito

There are countless different methods of doubting the validity of the cogito. The first of the three under scrutiny here concerns the nature of the step from "I think" to "I exist". The contention is that this is a syllogistic inference, for it appears to require the extra premise 'all thinking things exist' and that extra premise must surely have been rejected at an earlier stage of the doubt. Indeed, it appears to be untenable as a statement based solely on introspection. Descartes responds to this argument by conceding that there is indeed an extra premise needed, but denying that the cogito is a syllogism on the grounds that the extra premise—not 'all thinking things exist' but 'existence is necessary for thought'—is proved to be self evident by the cogito itself and is therefore receptive to analysis after the move from cogito to sum, but not present as a premise involved in the move. This response seems to be sound, but it anticipates another approach for criticising the cogito.

The second objection, that the notion that the cogito is not primary is intimated by the seeking of another premise before 'sum';, and is again hinted at by Nietzsche in Beyond Good and Evil: "in the sentence 'I think'…[there are] a series of rash assertions which are difficult, perhaps impossible, to prove." Perhaps the ultimate claim in this direction is that the cogito is only actually comprehensible if a whole swathe of assumptions are left unquestioned by the doubt. These would include: an understanding of the syntax and semantics of the language used; a notion of what it is to exist; a notion what thought itself is. These could be dismissed by Descartes as trivial, due to the fact that it is nonsensical to undermine assumptions in these areas; if you could do so philosophical investigation itself would be meaningless.

Perhaps a more relevant contention is whether the 'I'; that Descartes assumes is justified. In Descartes, The Project of Pure Enquiry Williams provides a history and full evaluation of this issue—the third argument—. The main objection, given full voice by Georg Lichtenberg , is that rather than supposing an entity that is thinking, Descartes should have just said 'there is some thinking going on'. What is not at stake here is circularity. Whilst the statement 'I think therefore I am', as a sentence proving the existence of an entity is circular, the concept of 'thought proving existence' is not. This is because (ignoring the actual content of Lichtenberg's argument) any thinking supposes the entity—the proof is inherent rather than question begging. Returning to Lichtenberg, what exactly is the force of the statement that Descartes states too much in 'locating' the thought? It seems as though 'thought' is less substantial than 'I think', and so Descartes, given his reductionistReductionism in philosophy describes a number of related, contentious theories that hold, very roughly, that the nature of complex things can always be reduced to (explained by) simpler or more fundamental things. This is said of objects, phenomena, expla manifesto, should be compelled towards the former. Whilst Williams is at pains to express why this is false, it seems that the best grounds for believing that it is false lie in its conceptual nature: "It is not at all clear that we really can grasp this supposed difference in the abstractThis article is about the concept of abstraction in general. For other uses, please see abstract (disambiguation). Abstraction is the thought process wherein ideas are distanced from objects. Abstraction uses a strategy of simplification of detail, wherei." The point being that conceiving of thought in an impersonal manner is paradoxicalFor other meanings of "Paradox", see Paradox (disambiguation). Robert Boyle's self-flowing flask fills itself in this diagram, but perpetual motion machines don't exist. A paradox is an apparently true statement or group of statements that seems to lead t. Perhaps in terms of parsimonyIn science, parsimony is the trait of being the least complicated explanation for an observation. This is widely held as a value for judging hypotheses. This value is embodied in Ockham's Razor. Parsimony is also used as a value in studies of molecular ev Lichtenberg was right, but in combination with the second contention, that there are some unshiftable assumptions underneath the cogito, it seems that simply have to moving on is the only option, and the thought will have to be re-located in an entity: 'I'.