Why it works
When we plan, we naturally picture success. Asking “it failed — why?” gives everyone permission to name problems, and it shifts attention to the assumptions most likely to break.
A 10-minute pre-mortem
- State the decision in one sentence.
- Say: “It's six months from now. This went badly.”
- Everyone writes down the most likely reasons it failed — silently, for three minutes.
- Share them and group the similar ones.
- For the top one or two, agree the cheapest check you can run now.
Using it on your own
You don't need a team. For personal decisions, write the failure story in a few lines, then ask which single fact, if wrong, would cause it. That's your cheapest check.
Frequently asked questions
What is the difference between a pre-mortem and a post-mortem?
A post-mortem reviews what went wrong after the fact. A pre-mortem imagines failure before you commit, so you can prevent it.
Does a pre-mortem make people negative?
Not when it ends with action. The goal is to find the one or two checks worth doing, then move forward with more confidence.