No. 340 · Fixing problems · Chemistry
Le Chatelier’s Principle
Push on a system in balance and it pushes back, settling into a new balance.
In the Almanac
“Le Chatelier’s rule”, 1884 · “Eli Lilly”, 2022–2024
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is Le Chatelier’s Principle?
Le Chatelier's Principle says that when a system in equilibrium is disturbed, it shifts to counteract the change and settles into a new balance. Chemists use it to steer reactions, and it also explains how markets, teams and our own bodies respond to shocks: every push invites a pushback.
How do you use Le Chatelier’s Principle?
To use it, ask what the counterforce will be before you act. Expect teams to compensate for sudden demands, make gradual health changes so your body doesn't fight back, and remember that bargains vanish when everyone rushes to them. Work with the pushback, not against it.
When does Le Chatelier’s Principle matter?
Le Chatelier’s Principle 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 “How systems push back”, alongside Bottlenecks, Ecosystems and Feedback Loops.
What is an example of Le Chatelier’s Principle?
Two stories show it at work: Le Chatelier’s rule (1884) and Eli Lilly (2022–2024). 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 Le Chatelier’s Principle?
Homeostasis, Feedback Loops and Cobra Effect. Le Chatelier’s Principle itself comes from chemistry.