René Descartes - The Father of Modern Philosophy

For centuries, philosophy was dominated by Aristotle and the Church. Then came René Descartes (1596–1650), a French mathematician and scientist who decided to burn the whole house down and start over.

He famously locked himself in a room with a stove and decided to doubt everything that could possibly be doubted.

Descartes asked: "What can I know for certain?"

• Can I trust my senses? No, they deceive me (optical illusions).
• Can I trust reality? No, I could be dreaming (or in a Matrix).
• Can I trust math? No, an "Evil Demon" could be tricking me into thinking 2+2=4.

He eventually hit something he couldn't doubt. Even if he is being deceived, he must exist to be deceived. Even if he is doubting, he must exist to doubt.

Cogito, ergo sum: "I think, therefore I am."

This single sentence shifted the focus of philosophy from "What is the world?" to "What can I know?" This focus on the subject (the self) is the birth of Modern Philosophy.

Descartes concluded that because he could imagine himself without a body, but not without a mind, they must be different things.

• Res Extensa: Extended things (Matter, the body, physics).
• Res Cogitans: Thinking things (Mind, soul, consciousness).

This created the Mind-Body Problem that still haunts us today (and is the root of the "Ghost in the Machine" concept).

Descartes made philosophy about Epistemology (Knowledge) first. He championed Rationalism—the idea that reason, not just observation, is the path to truth. He also invented the Cartesian coordinate system (X and Y axes), so you can thank (or blame) him for your algebra homework.

1. The Book:

• "Meditations on First Philosophy" by René Descartes.
• It's actually quite short and readable. It reads like a diary of a man having an existential crisis.

Next time, we jump forward to the man who declared God dead: Nietzsche.