Introduction

Cogito ergo sum—‘I think therefore I am’—is arguably the most famous and deceivingly simple adage in the history Western philosophy. The Cogito is important for Descartes’ project in the Meditations because it is the ‘rock and clay’ that he has been seeking as a foundation for his philosophy. There are two rival interpretations of the Cogito: as an immediate inference from the premise ‘I think’ or as an intuition in which ‘I think’ is not required as a premise. In this paper I will analyse these interpretations and argue that the only way the Cogito can be interpreted is as an intuition.

Beyond Unreasonable Doubt

• Premise A: I think
• Premise B: Everything that thinks exists
• Conclusion: I exist

There are two possible logical structures for this argument. First it may be an immediate inference—an inference from a single premise without need for any second general premise such as ‘Everything that thinks exists’; secondly it may be a truncated syllogism needing that further premise.

Descartes denies that the Cogito is an truncated syllogism because the second premise is not beyond doubt. The missing premise can only follow from the intuition about his existence. Descartes also argues that the Cogito is immediate and there is no movement of thought. The Cogito can also not be an inference because as long as Descartes has not refuted the possibility of a deceiving demon controlling our minds, all conclusions from inference are doubtful. What the demon hypothesis however can not bring into doubt is that it is me that is being deceived.

The Cogito as an Intuition

The notion of intuition is usually regarded with suspicion, as it can be considered simply labelling the place where philosophical understanding of the source of our knowledge stops. To determine whether this interpretation is philosophically superior we need to proof that ‘I think’ and ‘I exist’ are beyond all doubt. Descartes says that there is indeed something special about his belief that he is thinking and his belief that he exists; they are impossible to doubt. Descartes expresses the Cogito in the Second Meditation as an intuition:

… ego sum, ego existo, quoties a me profetur, vel mente concipitur, necessario esse verum (I am, I exist, every time it is declared by me, or conceived by my mind, it is necessary to be true).

It should be noted that Descartes stresses the first person element in his claim to certainty of the Cogito by adding the first person pronoun ego, which is superfluous in Latin as it is already implied by the word cogito. He wants to point out that because it is ‘I’ who is doing the declaring and the conceiving, ‘I’ must also exist. The propositions ‘I think’ and ‘I am’ have the special character of being incorrigible.

An incorrigible proposition satisfies the description: if I belief that P, then P. Incorrigible propositions are usually first person introspective thoughts like ‘I think’ or ‘I am in pain’. They are not necessarily true, but can not denied by me, since it is ‘I’ that am doing the thinking or being in pain. The denial of ‘I am thinking’ and ‘I exist’ are not logically false, but pragmatically self-defeating.

It could be argued that if the existence of the Self is self-evident, then Descartes could omit the intuition ‘I think’. This intuition is however required because at this stage Descartes is only proving that he is a thinking thing (res cogitans), for as long as he has not refuted the possibility of a Malicious Demon deceiving us about the existence of the world, all material things (res extensans) are doubtable. It is also for this reason that he can not say for example ‘ambulo ergo sum’ (I walk therefore I am), because to be able to walk he must after all first be able to prove that the material world exists. The intuitions ‘I think’ and ‘I am´ are thus inseparable.

Conclusion