What Did Descartes Certainly Know?

It is well-known that the philosopher Descartes, while searching for some truth beyond all doubt, observed: Je pense, donc je suis. He restated this idea in various places, once in Latin, as: Cogito, ergo sum. The phrase is widely known as The Cogito and is usually translated into English as ‘I think, therefore I am’. Descartes thus concluded that he knew something with absolute certainty.

Descartes’ line of enquiry here has some similarities with a practice adopted by students of non-duality and others: saying ‘not this’ to all thoughts and finite conceptions in search of the Self and the Real. The non-dual philosophy holds that the existence of Self is incontrovertible and requires no further proof. So here we find what seems to be common ground between the theory and practice of non-duality and a pre-eminent thinker in the Western philosophical tradition. This article will consider how far the two approaches do overlap, and also where their methods and conclusions differ, in order to see what help and guidance both offer in our own pursuit of Self-discovery.

Rene Descartes was born in 1596 in France. His family were aristocratic, and he never needed to work. He was educated by the Jesuits, who provided one of the best educations available anywhere at the time. As a young man, he travelled and studied widely, and among his early intellectual achievements were developments in analytical geometry so important that we still speak of ‘Cartesian coordinates’. With his roots in Jesuit Catholicism and the ambition of finding new and secure foundations for all departments of knowledge, Descartes has been called the ‘father of modern Western philosophy’.

In 1637 he published his Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences. The style is clear and accessible, and it contains much insight, a true spirit of enquiry, and some humour. It begins:

Good sense is, of all things among men, the most equally distributed; for everyone thinks himself so abundantly provided with it, that those even who are the most difficult to satisfy in everything else, do not usually desire a larger measure of this quality than they already possess.

He describes how he came to perceive the need for a revaluation of learning:

From my childhood, I have been familiar with letters; and as I was given to believe that by their help a clear and certain knowledge of all that is useful in life might be acquired, I was ardently desirous of instruction. But as soon as I had finished the entire course of study, at the close of which it is customary to be admitted into the order of the learned, I completely changed my opinion. For I found myself involved in so many doubts and errors, that I was convinced I had advanced no farther in all my attempts at learning, than the discovery at every turn of my own ignorance.

The problem, he concluded, was not merely personal:

And yet I was studying in one of the most celebrated schools in Europe, in which I thought there must be learned men, if such were anywhere to be found… I was thus led to take the liberty of judging of all other men by myself, and of concluding that there was no science in existence that was of such a nature as I had previously been given to believe.

So he gave up book learning and sought life experience.

For these reasons, as soon as my age permitted me to pass from under the control of my instructors, I entirely abandoned the study of letters, and resolved no longer to seek any other science than the knowledge of myself, or of the great book of the world. I spent the remainder of my youth in travelling, in visiting courts and armies, in holding intercourse with men of different dispositions and ranks… and, above all, in making such reflection on the matter of my experience as to secure my improvement.

He saw clearly how easily one falls into error and confusion:

I had become aware that no opinion, however absurd and incredible, can be imagined, which has not been maintained by some one of the philosophers…

He decided, therefore, to adopt four guiding principles in his pursuit of knowledge. They may be summarized as follows:

1. Only accept what is certain.
2. Break complex problems into as many parts as possible.
3. Proceed from the simplest to more complex.
4. Be thorough and omit nothing.

He also adopted three moral maxims to guide his practical life:

1. Obey the law and customs of the land in which he lived, avoiding extremes and following the most moderate opinions.
2. Be firm and resolute in decisions.
3. Try to change himself rather than the world.

This last is a finely expressed summary of stoicism, worth quoting at length:

My third maxim was to endeavor always to conquer myself rather than fortune, and change my desires rather than the order of the world, and in general, accustom myself to the persuasion that, except our own thoughts, there is nothing absolutely in our power; so that when we have done our best in things external to us, all wherein we fail of success is to be held, as regards us, absolutely impossible: and this single principle seemed to me sufficient to prevent me from desiring for the future anything which I could not obtain, and thus render me contented…

Then, mentally equipped with these maxims:

During the nine subsequent years, I did nothing but roam from one place to another, desirous of being a spectator rather than an actor in the plays exhibited on the theater of the world; and, as I made it my business in each matter to reflect particularly upon what might fairly be doubted and prove a source of error, I gradually rooted out from my mind all the errors which had hitherto crept into it.

After these years he finally settled, in the Netherlands, and began to seek a way through confusion and error to a new source of certainty. He began by pressing doubt to its limit. He thought:

that I ought to reject as absolutely false all opinions in regard to which I could suppose the least ground for doubt, in order to ascertain whether after that there remained aught in my belief that was wholly indubitable… Seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us… Because some men err in reasoning, even on the simplest matters of geometry, I rejected as false all the reasonings I had hitherto taken for demonstrations… Finally, when I considered that the very same thoughts which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams.

And here, in the deepest possible scepticism, he found what he believed was a foundation on which to start rebuilding philosophy and science:

But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think therefore I am, was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.

On this ground, he quickly established three more principles which he thought were equally secure:

His nature is a thinking being: he is a something that thinks.

What is true is what is ‘clear and distinct’ (self-evident).

God exists, being the perfect being on which all imperfect beings depend.

Descartes later expanded and restated his ideas in the Latin text Meditations on First Philosophy, published in 1641. There he began by supposing that he might be under the power of a malevolent demon. Even so, he concluded:

Let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something… I must conclude that this proposition, I am, I exist (Ego sum, Ego existo) is necessarily true whenever it is put forward by me or conceived in my mind.

Once again, he proceeded from this starting-point to find with equal certainty that his nature was a thinking being, that what is self-evident is true, and that the perfect Being, God, exists.

Descartes’ Discourse and Meditations are among the most-read works in the Western philosophical canon. But rather than establishing anything with certainty, he initiated philosophical controversies that continue unresolved to this day.