René Descartes’ famous “Cogito Ergo Sum” (I think therefore I am – which, incidentally, never appears in the Meditations, though Descartes did write that phrase elsewhere) has been challenged various times in very interesting ways by a number of thinkers, and has been transformed in others. What I want to do here is take a brief survey of some of the interesting ways in which other thinkers have confronted Descartes’ Cogito Ergo Sum.
First, Søren Kierkegaard argued that the argument was circular. Since existence is presupposed when one says “I,” the conclusion that “I exist” just restates the premise. In other words, the argument demonstrates something trivial at best. I myself would maintain that the argument makes us aware of what we already know as a self-evident and properly basic belief – that “I exist”. However, this apparently self-evident belief has not gone unchallenged either. A number of criticisms are aimed directly at the concept of “I” or the self, since this is what ought to be proved or demonstrated rather than assumed. Pierre Gassendi, according to Stanford Encyclopedia of philosophy:
points out that recognition that one has a set of thoughts does not imply that one is a particular thinker or another. Were we to move from the observation that there is thinking occurring to the attribution of this thinking to a particular agent, we would simply assume what we set out to prove, namely, that there exists a particular person endowed with the capacity for thought . In other words, the only claim that is indubitable here is the agent-independent claim that there is cognitive activity present.
Friedrich Nietzsche similarly suggested that we cannot presuppose the first person singular, and proposes that the third person singular would do just as well “I am thinking” becomes “it is thinking”. Bernard Williams advances a similar argument a little more violently since he suggests that the argument actually muddles what has to be first person singular with what has to be third person singular; namely, ‘I’ and ‘thinking thing’ respectively.
Other philosophers have been more charitable in their treatments of the Cogito, and many have suggested that the Cogito may prove even more than is realized. For instance, Jean-Jacques Rousseau, in his Essay on the Origin of Language explores the genesis of language, and others in the continental tradition have, it seems to me, come more or less to the same kinds of conclusions as he does. For Rousseau, language could not but arise in community and from the need to communicate the passions, for which mere gestures are inadequate. Rousseau, therefore, stunningly suggests “Cogito ergo estis” (I think therefore you all are – second person plural). Following this vein of thought, one might take Heidegger’s conclusion that “Language is the House of Being” to indicate that ‘existence’ along with “I” (personal pronouns in general) are language-concepts. That is to say, these categories cannot be divorced from language in principle, because they arise from within language and they have no ‘being’ apart from language.
This meditation on the philosophy of language leads, I think, to a more interesting conclusion still. If Language is the kind of thing which implies variety along with community (ie. if it is not logically possible to have language arise in a world without a community of speakers) and if thinking insofar as it is considered as a properly human action is simply a use of language (and thus a sort of speaking), it follows from that that thinking itself implies that “you (pl.) exist”. Further, since the existence of the self is literally self-evident, one might as well conclude “Thinking occurs, therefore we exist”.
Moreover, if we agree that identity and the self are only categorically possible given community (ie., it is not possible to have ‘persons’ without communities) then it follows from “I” that “we.” I can thus conclude from “I think” that “we exist.” I have no idea who ‘we’ refers to, and I have absolutely no good evidence to think that any particular person other than myself exists, but I can know that the first person plural of the verb ‘to exist’ has a referent in reality.
There are two possible objections I see, barring just dismissing the continental tradition out of hand. The first objection is that the argument is as circular as Kierkegaard thought the Cogito Ergo Sum was; since saying or thinking anything just implies language, and since language entails community, then I can prove that “we exist” only by presuming “we exist” insofar as “thinking” (considered as a kind of speech) requires community.
A second objection just would be that the Principle of Sufficient Reason isn’t true, and therefore perhaps language exists as a brute fact without community. However, I think that can easily be made into an argument for the PSR, since it seems that from the denial of the PSR nothing can ever be proved.