Cogito Ergo Sum — Lessons from Descartes

Seyone Chithrananda
4 min readDec 7, 2019


‘I think therefore I am.’

This legendary quote from Descartes may seem vague and confusing, but it was a realization that came from his unique, subjective approach to philosophy.

Rene Descartes was a 17th Century philosopher, and a fierce rationalist. During a time in which most philosophers validated their theories using appeals to God, Descartes believed only in one thing: the human power of logic.

Descartes had immense faith in what introspection guided by definition, sound argument, and clarity of thought could achieve. He believed that much of what was wrong with the world was caused by misusing our minds through confusion, bad definition, and unconscious illogicality

His life’s work focused on making our minds better equipped for the task of thinking. To solve key questions, Descartes believed that one should divide large problems into small, understandable sections by way of incisive, clear questions. He called this his ‘methods of doubts’, commonly referred to as thinking from first principles today.

We often get confused by tough questions like ‘What is consciousness?’, largely because we don’t spend enough time breaking down these big questions. To understand the nature of consciousness, one must break down the brain into its smallest components, the neocortex, hypothalamus, cortices, tracts and more.

If we choose to go even deeper, we can look at the neural circuits and computations that occur on the level of individual neurons. And that’s just if we choose to look only at the brain.

Descartes fundamentally believed in grounding all of our ideas in individual experience and reason, rather than authority and tradition. In his greatest book ‘Discourse on the Method’ published in 1637, he explained how he had come to write it:

‘A long time ago, I entirely abandoned the study of letters resolving to seek no knowledge, other than that which could be found in myself or else in the great book of the world, I spent my youth traveling visiting courts and armies, mixing with people of diverse temperaments and ranks gathering various experiences, testing myself in situations which fortune afforded me, and at all times reflecting personally upon whatever came my way so as to derive some profit from it.’

One could say Descartes had an unconventional childhood!

Through his unique childhood and experience, he came to the conclusion he’s most known for.

‘Cogito ergo sum’ — ‘I think therefore I am’.

After thinking about which truths he could deduct absolutely, he reasoned that the only truth he could absolutely know for certain is that he exists because if he didn’t, he wouldn’t be able to think.

It was intended to be Descartes’ ultimate answer to a question that philosophers, sometimes get perhaps unreasonably interested in, namely, ‘How can one know that anything including oneself, actually exists rather than being some sort of dream or phantasm?’

On his quest was certainty around this question of whether it might all be a dream

Descartes began by observing that our human senses are deeply unreliable. He couldn’t, for example, he said, be trusted to know whether he was actually sitting in a room in his dressing gown next to a fire, or merely dreaming of such a thing.

But there was one thing he could know for sure: he could trust that he was actually thinking.

This extreme form of questioning, also known as cartesian scepticism, isn’t meant to be a practical exercise, but rather a philosophical one. In our everyday lives, it makes much more sense to just make assumptions about pretty much everything, since those assumptions, regardless of whether they are true or not, allow us to reach conclusions.

However, when focusing on a less certain challenge, like understanding the nature of reality or solving a difficult problem, assumptions don’t suffice–objective truths are needed, or at least something close to them.

As a result, it’s no surprise that Descartes had such a profound impact on science and mathematics. His desire to seek objective truth led him to develop the scientific method and several important mathematical concepts (including the cartesian grid, analytical geometry, and more), all of which are used all over the world today.

Descartes was a man who spent his life searching for the ultimate, objective truth, who developed remarkable ideas along the way. Although questioning absolutely everything about everything is an easy way to spiral into a pit of hopelessness, it’s a great exercise to develop your ability to think critically, so try it out!

Thanks for taking the time to read through my thoughts on Descartes! If you have any questions or comments, feel free to chat with me on Twitter. Or if you would like to learn about any new content I put out, subscribe to my monthly newsletter to see new projects, conferences I go to, and articles I put out!

Thanks again,

Seyone 😃



Seyone Chithrananda

19-year old interested in hard-tech, biology, and philosophy.