The cogito argument

In the Latin translation of the Second Meditation, Descartes writes that

If I convinced myself of something then certainly I existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly exist, if he is deceiving me…he will never bring it about that I am nothing so long as I think I am something…I must conclude that this proposition, I am, I exist is necessarily true whenever it is put forward by me or conceived in my mind.

However, in the (later) French translation, approved by Descartes, the emphasis is slightly different:

I certainly existed, if I convinced myself, or simply if I thought anything.

And it is only in the Discourse that we get the explicit, and most famous form, ‘I am thinking, therefore I exist’.

The argument is not logically necessary, but it is – as Bernard Williams puts it – “pragmatically” necessary. It is pragmatically self-defeating to deny ‘I am thinking’.

Knowledge not requiring explanation

In the Principles I.60 – tellingly titled “that there are notions so clear in themselves that one renders them obscure by trying to define them in the scholastic manner, and that these notions are not acquired through study, but are born with us” – Descartes argues some terms are ‘sufficiently known in themselves’ and therefore do not require explanation.

Descartes claims that ‘thought’, ‘existence’ and ‘certainty’ are simple notions that do not provide knowledge of any existing thing. We need these terms to understand the cogito, but we do not need their definitions to know what they mean. Hence ‘I think, therefore I am’ is the “first and most certain proposition” to orderly philosophising, notwithstanding a lack of definitions for the terms involved.

Clear and distinct

In the Rules Descartes talks about intuition and deduction as the only sources of certainty. Deduction is the inference of something following necessarily from other, certainly known, propositions. Intuition is the faculty by which we gain the certainties that make deduction possible: it is the immediately self-evident “conception of a clear and attentive mind”.

Descartes holds that propositions immediately inferred from self-evident intuitions can be described as either intuition, or deduction.

Descartes’ talk of intuition and deduction gives way to notions of clarity and distinctness in the Discourse, Meditations and Principles. Though Descartes never announces these ideas to be equivalent, Markie notes that their similar descriptions makes it likely they are supposed to be.

In the Principles I.45, Descartes defines

Clear perception is “present and accessible to the attentive mind”. This is meant to be analogous to clarity in sense perception, in that a perception is clear when it is present to the eye’s gaze and stimulates the eye with sufficient strength.

Distinct perception is clear perception that is also “so sharply separated from all other perceptions that it contains nothing within itself, only what is clear”.

So clarity and distinctness relies on us as thinkers: we have to be attentive. Clarity and distinctness need not be obvious at first sight, for example with logic or mathematics. We have to ensure we look through all the steps and assimilate them, and judge things could not be otherwise. Conversely, that something is obvious does not make it clear and distinct.

What is the link between certainty and truth anyway? For Descartes, certainty is a sufficient condition for truth. But Descartes never provides a great deal of explanation for this. He swims between three ways of understanding certainty:

1. As a first-person point of view: to be certain that X is to believe it’s true.

2. Certainty as a psychological state.

3. As a logical position, concerning what ought to be doubted.

What is meant by cogito

Bernard Williams points out that the French and Latin words generally translated as ‘think’ in English (penser and cogitare, respectively) have a much wider meaning than the English word. For Descartes, a ‘pensée’ could be any sort of conscious state or activity whatsoever. In the Second Meditation, for example, he includes doubting, understanding, asserting, denying, willing, imagining and feeling into the nature of a ‘thinking thing’. In the Principles, thought includes not only the faculties of cognition, but also “sensory awareness”.

It is not always clear where Descartes intends a ‘wide’ reading of ‘thinking’ and where he intends a narrower, more English-like, reading.

Williams argues that, despite this, it is not sufficient to claim – as some of Descartes’ objectors have – that one could argue ‘I am breathing, therefore I exist’. Instead, the force of the ‘I am breathing’ claim is that the presentation of the thought entails that we are thinking, and so the argument goes through as usual.

What is the ‘I’ involved?

The Lichtenberg objection: Descartes is not able to infer that there is an ‘I’ to exist. At best he can infer ‘there are thoughts’, or ‘there is thinking going on’.

Gary Hatfield suggests the following readings of the cogito argument:

1. A thin reading: the thinking thing is wholly constituted by the thoughts present to the meditator.

This reading seems to avoid the Lichtenberg objection, but is contradicted by Descartes’ writing in the Third and Fifth Replies, where Descartes asserts that thoughts, as accidents, must persist in a substance. Given that Descartes claims to reserve a full understanding of mind-as-substance-distinct-from-body for the Sixth Meditation, this suggests

2. A thinking substance as immaterial being reading: the thinking thing is a substance, but there is no claim about its (non-)identity with body.

Over the following ‘thicker’ reading

3. A thinking substance as distinct from body reading: the thinking thing is an immaterial substance, distinct from body.

Form of the cogito

The cogito argument is certainly forceful. However, given the meditator’s state in...

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