Thinking tools
Inversion
Work a problem backwards by asking what would guarantee failure, then make sure you avoid it.
The mathematician Carl Jacobi, who advised "man muss immer umkehren" (invert, always invert); popularised by Charlie Munger.
Most planning runs forward: here is the goal, what steps get me there? Inversion runs the other way. You ask what would make the project, the relationship or the investment fail for certain, write those things down, and then check whether you are doing any of them. Munger put it as a joke: all he wanted to know was where he was going to die, so he would never go there.
It works because failure is often easier to see than success. Ask a team how to ship a reliable service and you get vague answers. Ask how to guarantee an outage and you get a concrete list: no alerts, untested backups, one person who knows the deploy script. Avoiding a known list of mistakes is a tractable task.
Inversion finds what to avoid. It does not tell you what to build. Someone who only removes failure modes can end up cautious and stuck, with a plan that cannot fail because it never tries anything. Use it to check a plan you already have, then go back to thinking forwards.
Example
On 13 June 1986 Charlie Munger gave the commencement speech at the Harvard School in Los Angeles. Instead of advice on how to succeed, he gave prescriptions for a guaranteed life of misery: be unreliable, learn only from your own experience, stay down after a bad setback, and ignore inversion. He borrowed the format from an earlier talk by Johnny Carson, whose list included mood-altering chemicals, envy and resentment.
Where it applies
Before a launch, run a pre-mortem: assume the project failed six months from now and list the reasons. For an artificial intelligence (AI) feature, ask what inputs would make the model produce the worst possible answer, and test those first.
Think about it
What would you do this week if your goal were to make your most important project fail, and are you doing any of it already?
Applied it to something real? Log it.
Test yourselfHow does inversion change the question you ask about a goal?
Instead of asking how to succeed, you ask what would guarantee failure, then you avoid those things.
Related models
- Second-order thinkingKeep asking "and then what?" until you have looked at the consequences of the consequences.
- Chesterton's fenceBefore you remove a rule, a process or a piece of code, find out why someone put it there.
- Pre-mortemBefore you start, imagine the project has already failed and ask everyone to explain why.
- Via negativaImprove things by removing what does harm before adding anything new, because we usually know more about what is wrong than about what is right.
- Confirmation biasPeople look for, notice and remember evidence that fits what they already believe, and rarely test what would prove them wrong.