Author

René Descartes

16 key ideas across 2 books, each explained in our own words.

Discourse on Method

IDEA 1
Descartes tells how he sought truth
Descartes describes his own education and his disappointment that the schools taught so much that was uncertain. He decided to find a reliable method for reaching truth, and he presents his search as a personal story rather than a textbook.
IDEA 2
Accept only what is evident
His first rule of method is never to accept anything as true unless it is so clear and distinct that it cannot be doubted. This rule guards against hasty judgement and prejudice.
IDEA 3
Divide difficulties into parts
Descartes's second rule is to break each problem into as many small parts as possible. Smaller parts are easier to understand and solve. Complex problems become a series of simpler, manageable steps.

IDEA 1
Doubt everything that can be doubted
Descartes decides to throw out every belief that he can find any reason to doubt, hoping to discover something completely certain. If knowledge is like a building, he wants to clear away shaky foundations and start again on solid ground.
IDEA 2
The senses can deceive us
Descartes notes that his senses have sometimes fooled him, and that dreams can feel as real as waking life. So he cannot be sure, from experience alone, that the world around him is as it seems or even that he is awake.
IDEA 3
Imagine a powerful deceiver
To push doubt to the limit, Descartes imagines an evil demon who might be tricking him about everything, even simple mathematics. This thought experiment tests whether any belief could survive such total deception.

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