No. 327 · Fixing problems · General Thinking
First Principles Thinking
Strip a problem back to what you know is true, then build up again from there.
In the Almanac
“Euclid’s five postulates”, c. 300 BC · “Impossible Foods”, 2016
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is First Principles Thinking?
First Principles Thinking means stripping a problem back to the basic facts you know are true, then reasoning upward from them rather than copying what everyone else does. It's how breakthroughs happen when an industry's assumptions turn out to be wrong.
How do you use First Principles Thinking?
To use it, ask what the goal actually is and what must be true to reach it. Question costs and processes that seem fixed. Save the effort for decisions that matter most.
When does First Principles Thinking matter?
First Principles Thinking is one of the 40 mental models for fixing problems, the situations where you ask: Why does this keep going wrong, and how do I fix it for good? Within that, it belongs to “Finding the real cause”, alongside Black Box, Inversion and Lateral Thinking.
What is an example of First Principles Thinking?
Two stories show it at work: Euclid’s five postulates (c. 300 BC) and Impossible Foods (2016). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to First Principles Thinking?
Back-of-the-Envelope Calculation, Paradigm Shift and Scientific Method. First Principles Thinking itself comes from general thinking.