The Best-Practice Inversion Interview
Ask a candidate for a best practice, then for when it would not apply
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 2
- Confidence
- 82%
A two-part interview question that tests whether a candidate understands why a practice works, not just that it works. First they describe and narrate a best practice they learned; then they name a situation where that practice would not be applicable. Most people cannot do the second part, which reveals cargo-cult versus first-principles thinking.
Origin
Eric Ries's favorite interview question, reflecting his broader distaste for 'Just So Stories' where people copy tactics (Steve Jobs's black turtleneck) without understanding causation.
Core principles
- 01Knowing a practice works is not the same as knowing why it works
- 02Understanding boundaries (when it fails) is the real signal of comprehension
- 03Advice copied without understanding causation is a 'Just So Story'
How to run it
- 1
Elicit a best practice with its story
Ask the candidate to describe a best practice they learned in their career, and to really get into how they learned it.
Pro tip Let them run — the narrative reveals depth of experience.
- 2
Invert it
Then ask them to describe a specific situation where that best practice would not be applicable.
Pro tip The inability to answer is itself the diagnostic — most people can't do it.
Watch out A candidate who treats the practice as universally true likely learned it by imitation, not by understanding why it works.
In the wild
Ries recounts that startup advice used to take the form 'Steve Jobs did this thing, so if you do it too you'll be like Steve Jobs' — but he also wore a black turtleneck, so which part actually causes the result? He wanted to understand why something works and whether it's still appropriate for a given industry.
→ Motivates an interview question that separates people who understand causation from those who parrot tactics.
Common mistakes
Hiring for practice-recall instead of causal understanding
A candidate who can list best practices but can't say when they'd fail will misapply them in novel situations.
Is it for you?
Best for
Hiring managers screening for first-principles thinkers who understand the boundary conditions of their expertise
Not ideal for
Roles that genuinely require rote execution of a fixed, well-bounded procedure
From the transcript
“ask people to describe a best practice that they learned in their career”
“great tell me a situation where that best practice would not be applicable most people can't do it”
From the episode
Reflections on a movement
Eric Ries (creator of the Lean Startup methodology)