Discourse on the Method (1637) marks the beginning of modern philosophy. Descartes sought certain foundations for knowledge, sweeping away centuries of scholastic tradition to build a new philosophical system from undoubtable first principles.
The Method of Doubt
Descartes resolves to doubt everything that can possibly be doubted. Our senses deceive us. We might be dreaming. Perhaps an evil demon manipulates our thoughts. Most beliefs, it seems, lack certain foundations.
“I resolved to reject as false everything in which I could imagine the least doubt.”
But in the very act of doubting, one thing becomes certain: the doubter exists. “I think, therefore I am” (cogito ergo sum) survives even the most radical skepticism.
Building Knowledge
From this foundation, Descartes rebuilds knowledge. The cogito establishes the existence of the thinking self. Clear and distinct ideas—like mathematical truths—are reliable. God exists and guarantees our rational faculties.
The result is a systematic philosophy grounded in reason rather than authority or tradition.
Mind and Body
Descartes famously distinguished mind from body. The mind is a thinking, non-extended substance. The body is an extended, non-thinking machine. This dualism creates the enduring “mind-body problem”: how do these different substances interact?
Scientific Method
Beyond metaphysics, Descartes contributed to scientific methodology:
- Break problems into smaller parts
- Proceed from simple to complex
- Use mathematical reasoning
- Review comprehensively
Legacy
The Discourse inaugurated a new era. Philosophy became focused on epistemology—how do we know what we know? The demand for certainty and systematic method shaped centuries of thought. And the mind-body problem remains unsolved.