“I think, therefore I am.” It is probably the most famous statement in philosophy, and René Descartes was the man who wrote it. Born in France on the 31st of March 1596, he was educated at the Jesuit College Royal Henry-le-Grand at La Fleche, and then in canon and civil law at the University of Poitiers at a time when the medieval worldview was giving way to the science of the Enlightenment.
He never practiced law, instead choosing to join the Dutch States Army in 1618 to train as an engineer. On St. Martin’s Day in November 1619, he experienced a series of visions which convinced him that the path to true wisdom lay through the study of science. He left the army a year later, arriving in La Haye in 1623 and investing in bonds. It was the income from these which gave him the freedom to focus on philosophy. He returned to the Netherlands in 1628, and it was here, over the course of more than twenty years, that he would write all his major philosophical works.
Initially he concentrated on mathematics, and remains a key figure in geometry, algebra, and calculus. Among his more recognisable achievements in this field (bearing in mind that I dropped mathematics before my final year of high school) was using the terms a, b and c for known variables, and x, y and z for unknown variables in equations.
In 1634, in Amsterdam, Descartes had a relationship with a serving-girl, Helena Jans van der Strom, who bore him a daughter, Francine. Sadly, Francine died at the age of five, and her death apparently affected her father deeply. In fact, I can’t help but wonder whether it may have been this loss which nudged Descartes away from a focus on mathematics and towards a greater interest in metaphysics.
Certainly, it was in the world of metaphysics (the ‘big questions’ of causation, the nature of being, the existence of God) and epistemology (knowledge and how we know what we know) that Descartes really made his mark on philosophy. And his ideas in this field are remarkably accessible, being contained in the six ‘meditations’ of his ‘Meditations on First Philosophy’, a book which is less than a hundred pages long and still required reading for many philosophy courses today (and, conveniently, available to read free online).
The starting point for the ‘Meditations’ marked a sea-change in how philosophy was done. Instead of asking ‘what is true?’, Descartes asked ‘what can I be certain of?’. On the surface these questions look deceptively similar, but when you think about it they’re actually quite different. It is to this question of certainty that Descartes answers “I think, therefore I am” (“cogito ergo sum”), or, more elaborately “I am, I exist, is certain, so long as it is put forward by me or conceived by my mind.”
From here we move on to what is known today as ‘Cartesian Dualism’, the idea that the mind and the body are completely different things (a distinction which is found long before Descartes, for example in the teachings of the Gnostics of early Christianity), although Descartes himself writes that ‘nature teaches me by these sensations of hunger, thirst, pleasure and pain that I am not merely present in the body like a sailor in a ship, but that I am very closely conjoined and intermingled with it so that I and the body form a unit.’
A devout Catholic throughout his life – which didn’t spare him from being branded an atheist by some and having his works banned by the Catholic church – Descartes devotes a not-inconsiderable amount of time in the ‘Meditations’ to rational arguments for the existence of God, taking the ontological view that, since he can conceive of God and, when he does so, conceives of God as perfect, and since being non-existent would be an imperfection, God, who is perfect, must exist. Even I regard this as a not-particularly-good argument, and suspect that in reality Descartes was seeking to rationalise his faith rather than embracing faith because it was rational. Which perhaps just goes to show that Descartes, at least, wasn’t perfect!
In 1649, Descartes was invited to Sweden by Queen Christina, to start a new scientific academy and be her personal tutor. Lessons were held three times a week at 5am, but it seems that the two didn’t get on, and the cold climate and early hours took their toll on Descartes. In February of 1650 he fell ill, and less than two weeks later, on February 11th 1650, he died of pneumonia. Initially buried in Stockholm, his body was exhumed in 1666 and returned to France, then moved again in 1819 to the Abbey of Saint-Germain-des-Prés, although his skull is displayed in the Musée de l’Homme in Paris.
His most significant works are: ‘Discourse on the Method’ (1637), ‘Geometry’ (1637), ‘Meditations on First Philosophy’ (1641), and ‘Principles of Philosophy’ (1644).