Plato's Heaven

I think, therefore I am

"I think, therefore I am." Almost everyone has heard of this famous saying before, but what does it mean?

It comes from René Descartes, a great philosopher who lived in the 17th century. The phrase sums up one of the arguments he gave in his Meditations. Of all the philosophical reading that I have ever done (and I've done quite a few), none have been quite so shocking to me as this one. It's similar to the shock that you get when you realise that Bruce Willis was dead the whole time in the Sixth Sense. You have to reasses everything and suddenly everything that you had previously believed seems like a false illusion...

Descartes is sitting comfortably by the fire. He decides to take on the challenge of discovering if there is anything that we humans can be certain of knowing. Can we be sure, for instance, that he is in fact sitting comfortable by the fire? He thinks that he could be having a dream. We think that we might be in a matrix. If we can't be sure that our reality is real, what can we be sure of?

Descartes begins his search by pretending that there is a demon who is continually inserting false beliefs into his head. So now, when he sees and feels the warmth of the fire, he can't be sure that the fire is there; the beliefs that he is having these sensations could have easily been made by the demon. Descartes leaves his writing for a little in this skeptical frame of mind, being cautious not to be deceived by the demon. Everything that he sees, hears, touches, smells and tastes is no longer an indication of what is.

So when he returns to his writings, what does he find? He has realised that the whole world might be an illusion created by the demon. Nothing around him, not even his own body, necessarily exists. But there is one thing that he can be sure of: that he has thoughts. His mind must exist. Otherwise, if the demon wanted to make him believe that he had no mind, he would have to insert that belief into his head, and he couldn't do this unless Descartes had a mind. Therefore, logical necessity suggests that if there is anything that we can be sure of, it is of the existence of our minds. Hence, "I think, therefore I am."

This doesn't mean that everyone must have a mind - it means that you can only be sure that YOU have a mind. You might like to try mistrusting everything you see for the next few days, it really is bizzarre. Of course, you don't have to believe in the demon, only the possibility that what you believe about this world may be entirely false.


Further Reading:

• Descartes, R., Meditations on First Philosophy
• Bouwsma, O. K., 1949, "Descartes' Evil Genius", Philosophical Review 58, pp. 141 - 151

posted by Niki Saunders @ 12:35 AM