Descartes: Pied Piper

Descartes: Pied Piper

I was educated in engineering but also had some interest in philosophy. My first philosophy course was Descartes' "Meditations on First Philosophy". I suspect this is an introductory course for most students studying philosophy. Descartes has left Western tradition with a gigantic legacy that only now is this legacy being undermined by cognitive science.

Descartes goes through a sequence of analysis in an effort to find an absolute truth upon which to build his philosophy. He settled on "Cogito, ergo sum". "I think therefore I am". The conclusions of this series of analysis by Descartes have set the course, more or less, of Western philosophy. What are the fateful conclusions derived from the work of Descartes?

"I am, I exist, that is certain. But how often? Just when I think; for it might possibly be the case if I ceased entirely to think, that I should likewise cease altogether to exist...But what then am I? A thing that thinks."

The Folk Theory of Essences
Every kind of thing has an essence that makes it the kind of thing it is.
The way each thing naturally behaves is a consequence of its essence.

Descartes knows he exists because he thinks. Because he exists he has an essence. He assumes nothing else causes his thinking but his essence. Conclusion: thinking must be at least a part of the human essence.

"Just because I know certainly that I exist, and that meanwhile I do not remark that any other thing necessarily pertains to my nature or essence, excepting that I am a thinking thing, I rightly conclude that my essence consists solely in the fact that I am a thinking thing."

"It is certain that this I [that is to say, my soul by which I am what I am], is entirely, and absolutely distinct from my body and can exist without it."

To have reached that last conclusion Descartes must assume an additional:

The Folk Theory of Substance and Attributes
A substance is that which exists in itself and does not depend for its existence on any other thing.
Each substance has one and only one primary attribute that defines what its essence is.

The following is what his introspection has made him "see":

There are two kinds of substance, one bodily and the other mental.
The attribute of bodily substance is extension in space.
The attribute of mental substance is thought.