Decision OS / Premortem
Let the future failure speak before the plan becomes identity.
Surface hidden assumptions, weak signals, dissent, and preventable risks before commitment hardens.
Case notes
Premortem makes the decision process visible before the outcome arrives.
A premortem is a disciplined act of imagination. It assumes the future failure has already happened and asks why. This gives risk permission to speak before optimism, status, or sunk cost takes over.
The point is not pessimism. The point is risk design. A good premortem converts assumptions into checks, safeguards, staged gates, or experiments.
01
Assume the decision failed.
The exercise works because it bypasses defensive planning.
02
Name assumptions, not only disasters.
Most failures begin as quiet assumptions.
03
Convert risk into design.
A premortem should change the plan, not just scare the team.
Common problems and experiments
Make the next process move small enough to test this week.
I feel disloyal imagining failure.
Experiment
Frame the premortem as protecting the decision, not attacking it.
What to watch
Dissent gets safer when it serves the outcome.
The risks are vague.
Experiment
Write the headline: 'Six months later, this failed because...'
What to watch
A specific future failure creates sharper assumptions.
Nothing changes after the premortem.
Experiment
Turn the top risk into one gate, mitigation, or experiment.
What to watch
Risk design is the output.
Prompt to try
Keep one decision sentence visible.
It is six months later and this decision failed. What did we miss, ignore, or assume?
7-day protocol
The premortem session
- 01 Write the preferred decision.
- 02 Imagine it failed later.
- 03 List ten possible reasons.
- 04 Circle the top three assumptions.
- 05 Create one mitigation for each.
- 06 Create one gate or experiment if possible.
- 07 Rewrite the decision card with the new risk design.
Decision checklist
Mark the process, not the outcome.
Source notes
Project premortem
Gary Klein describes premortems as a way to surface risks before a project begins.
Open source →Implementation intentions
If-then planning can convert premortem risks into concrete safeguards.
Open source →Education-only scope
Premortems support thinking; they do not replace professional risk assessment in high-stakes domains.