Descartes’ cogito, or his famous statement, “I think therefore I am” allows him to assert that he exists because he thinks. The cogito was established before any of Descartes’ later claims in Meditations because it was the first truth he proved after his method of doubt.  It is the first principle he discovers on which all other principles can build.

An argument to the cogito, which states all actions can prove existence, is not legitimate because all actions are thinking one is doing the action and therefore also thinking. An unsuccessful aspect of the cogito is Descartes’ failure to prove the existence of a specific “I” who is doing the thinking. Although the cogito is a mostly successful, well thought out and little disputed principle, the oversight of assuming the “I” is proven and not actually giving much proof to this statement lessens its overall effectiveness.

The cogito states the principle because he thinks, no matter what these thoughts are or how they occur, he therefore exists. He comes to accept the cogito as fact after constructing a method of doubt, in which he cleared his mind of all principles he perceived as fact in order to prove what was fact and what was not fact. The cogito is successful because it establishes a core on which other principles can build and because it doesn’t make any claims about the nature of thoughts. An argument to the cogito says any action, real or imaginary, can prove one’s existence as well as the verb “thinking” can. The cogito is unsuccessful in that it doesn’t have much proof for the “I” he alleges is thinking.

Descartes’ cogito establishes that because he thinks, no matter what he thinks or how these thoughts occurred, he exists. After going through a list of what he believes he perceives and believes he understands, known as the method of doubt, Descartes realizes “thought; this alone is inseparable from me.” Then, he adds it doesn’t matter if he is being deceived in his thoughts, perhaps by “a deceiver of supreme power and cunning” because even if he is being deceived, he is still thinking.

Another property of the cogito is that Descartes establishes it before he asserts anything else, including about whether or not God exists or about the nature of the world. Because he cleared his mind when formulating the Meditations, at this point he thought of none of his long-held beliefs as truth. The first truth he proved was the cogito. The cogito is the base on which all of the rest of his principles are built. For example, one cannot and doesn’t need to know anything of the world if one doesn’t exist or one doesn’t think.

The cogito is successful as the base for all of Descartes’ future theories because Descartes doesn’t make any un-established claims which couldn’t be proven until this base was demonstrated. For example, if Descartes made any claims about the nature of what he was thinking, they would be unproven (if they were imagination, dreams, or images from the real world) it would go against his objective of discarding preconceived notions, therefore lessening the cogito’s argument.

In trying to prove the cogito an unsuccessful argument, one skeptic says the cogito is unsuccessful because any sort of action, not just thinking, could have proved existence. However, any action above or beyond thinking is superfluous since every action can be reduced to simply thinking. For example, the action of running is essentially “I think I am running,” and therefore “I think.”