DAY 8 - Rene Descartes

Cogito Ergo Sum (I think, therefore I am)

Right now you might feel a little doubtful about, well, everything! If so, don't worry... you aren't alone. Back in 1641 famous modernist philosopher and mathematician Rene Descartes essentially rationalized (thought without experimenting) his way to a very frightening conclusion: he might not exist! Fortunately, Descartes was able to convince himself otherwise and revolutionized the mind-body argument when he wrote his famous Meditations on First Philosophy.

How did he do this? Actually, he was sort of watching the 16th century version of reality tv; he was sitting in a chair, looking out his window at a man in a trench coat. Because he could not see the man's face, he realized that he had no real proof that the man was in fact a man. He could be something else (perhaps a robot) dressed as a man. This startling conclusion led him to begin a mammoth thought experiment centering on doubt; in essence, what can you really know for certain?

Think of all the certainties that you take for granted: the sun rises, your senses don't (usually) lie to you, family members exist, friends are fun to hang out with, etc. Descartes, however, started doubting all of that, and more. As he himself says in his "First Meditation", "Several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful; and from that time I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation..." (Réné Descartes, The Method, Meditations and Philosophy of Descartes [1637]).

In the end, Descartes rationalized away everything from his bathrobe to his body. He just couldn't prove, necessarily, that he wasn't either dreaming or being tricked by some malicious evil spirit. Today we might compare his concerns to being either downloaded into a virtual reality machine (ala the Matrix) or being a brain in a jar being fed false sensory stimuli. And if you think that sounds too sci-fi, just remember the famous "I smell burnt toast!" exclamation from a surprised epilepsy patient whose brain was being electrically stimulated by Doctor Penfield back in the 1930s. Think of it this way: can you prove without any doubt that you are not dreaming, hooked into a computer or a brain in a jar?

Fortunately, Descartes' doubt was not infinite. He realized that although he could doubt everything from his friends' existence to his own senses, he could not doubt that he was thinking (otherwise, he wouldn't have had that thought). This simple realization allowed Descartes to infer the necessary and sufficient existence of himself ("I think, therefore I am") and time (since memories must be from a time that is not now). This foundation permitted him to later "prove" the existence of the body, senses and even God.

 Required Reading
For your activity you will be reading the first two Meditations from Descartes' Meditations on First Philosophy. Read an edited version of his first and second chapters below . If you want to read Descartes' entire Meditations on First Philosophy or have a helpful study guide, then check out the Resources section.

Edited "Meditations on First :Philosophy".


Pre-Assignment Practice: As you read try to identify the main points in Descartes' writings. Are Descartes' arguments valid? Why or why not? Consider how his arguments might be improved upon.

EnrichmentBefore continuing, you may want to play a web-based game called "Philosophical Health Check" where you can discover for yourself whether you accept the brain in a jar possibility. Click here to start.

 Resources

1. Necessary vs. Sufficient Conditions
2. Concepts of Necessary and Sufficient
3. Dualism
4. Aristotle's Metaphysics Summary
5. Meditations on First Philosophy