The art of thinking · Philosophy and logic
Cartesian method
Also known as: Descartes' method, Methodical doubt, Cartesian doubt
In philosophy, the Cartesian method is the procedure René Descartes set out in his Discourse on the Method (1637): accept nothing as true that is not clearly and distinctly known, divide each difficulty into as many parts as needed, reason in order from the simplest to the most complex, and review everything so that nothing is left out.
- Thinking models
- Philosophy
In one sentence
Descartes’ four rules (1637): accept only what is clearly known, divide each difficulty, reason from simple to complex, review so nothing is missed.
Example
Faced with a confusing troubleshooting chapter, a writer sets aside every statement that nobody can confirm, splits the fault into its parts, explains the simplest checks first and finally checks that every fault code is covered.
Explained in context
Context cards connect this term with others to answer one question. Also in British English and German.
How it applies
- The four rules: Evidence (accept only what is clearly and distinctly known), division (split each difficulty into as many parts as possible and needed), order (from the simplest to the most complex), enumeration (reviews so complete that nothing is omitted).
- Methodical doubt: In the Meditations on First Philosophy (1641), Descartes doubts everything that can be doubted to find a foundation that cannot — the "I think, therefore I am". His Principles of Philosophy (1644) then build a whole system on such foundations.
- First principles thinking: The modern three steps — question, break down, rebuild — are close to Descartes' first three rules. The fourth, the complete review, is often forgotten and matters most in documentation: a structure rebuilt from fundamentals still has to cover every task, mode and hazard.
Cartesian method vs. first principles thinking
Descartes searched for certainty. Modern first principles thinking settles for the most basic facts that can be verified in the case at hand — physical, economic or, in documentation, the facts of the product and its users.
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