René Descartes (1596-1650) was a French philosopher who laid the foundations not only for much of modern philosophy, but also for modern science. A key thinker in the history of thought.”I think therefore I am” is probably the most famous line in the history of philosophy. But it may not be that accurate.
Descartes belonged to the Rationalist school of philosophy that believed that reality has certain fundamental truths, an inner logic, which can be understood through intellect alone. Reason can figure out fundamental truth by itself.
Descartes set out to show that knowledge was intrinsic, that truth could be ascertained by reason alone. Descartes adopted a position of “radical doubt” – he doubted everything that could possibly be doubted.
The idea was to be skeptical of any claim that could conceivably be untrue, and therefore to discover whether there existed any claim which was absolutely undoubtable, absolutely certain, and absolutely true, through reason alone and without empirical observation from things in the ‘world’.
Descartes imagined a powerful “demon”, a deciever which could create an illusion of reality. This demon, Descartes reasoned, could have created a world in which nothing was actually real, in which even mathematical truths (2+2=4) were false.
How could we ever be certain of anything?
He realised that every possible belief could be doubted, and by accepting those doubts, he put himself in the position of believing that nothing was true.
But then, he realized the act of doubting was only possible if a being existed to do that doubting. And so, as he wrote: “I doubt, therefore I am — or what is the same — I think, therefore I am.”
But…..Descartes wrote in French and in Latin. In 1637 he wrote: je pense, donc je suis. And in 1647 he wrote: cogito, ergo sum. Both of them are usually translated as “I think, therefore I am”.
In translation it isn’t necessarily clear how either of those phrases should be written in English. Because, in English, you’ve got two forms of the present tense: the perfect and the continuous. It’s “I think” versus “I am thinking”, which have different meanings.
Descartes was presenting a fundamental, undoubtable truth which doesn’t rely on any other assumed truths:
1. All flowers have petals. 2. Roses are flowers. 3. Therefore roses have petals. That’s a syllogism. For Descartes’ idea it might be: 1. Only something which exists can think. 2. I think. 3. Therefore I exist. But that’s not what he was going for.
The point is that the act of doubting whether or not you exist (doubting being a form of thinking) necessitates that you must exist in the first place, otherwise there’s nothing to do the doubting…it is the act of thinking that makes this true.
An example that has been used is the difference between “I play football”, which you can say at any given point regardless of what you are doing at the time, and “I am playing football”, which means you are doing it right now.
Descartes realised, to say “I am doubting (a form of thinking)” necessitates that you exist while you are in the act of doing it, without the need for any other assumptions….it is, on its own, true.
Perhaps a nicer translation, written by the philosopher Antoine Thomas in 1765: “Since I am doubting, I am thinking; since I am thinking, I am existing.”