Pre-Mortem: Imagine Failure Before It Happens

What is a pre-mortem?

A pre-mortem is a meeting (or a solo exercise) where you assume your plan has already failed and work backward to explain why. It takes the post-mortem, which is normally done after a project dies, and moves it to the start, when the plan can still change.

The trick is in the framing. Asking “does anyone see any risks?” in a planning meeting rarely produces honest answers, because the room is invested in the plan and nobody wants to look negative. Saying “it is a year from now, this project failed badly; write down why” flips the social pressure. Naming problems becomes the task, not a betrayal.

A pre-mortem is useful before:

• Launching a product or a campaign.
• Signing a large contract, hire or partnership.
• Committing to a personal decision that is hard to undo.

Where it comes from

The pre-mortem was developed by Gary Klein, a research psychologist known for studying how experienced people such as firefighters and military commanders make decisions under pressure. He described the method in a short 2007 Harvard Business Review article, “Performing a Project Premortem.”

Klein’s article drew on earlier research on what was called “prospective hindsight”: a 1989 study by Deborah Mitchell, J. Edward Russo and Nancy Pennington suggested that imagining an event has already happened helps people come up with more specific reasons for it than simply asking whether it might happen. The pre-mortem turns that finding into a team routine.

The technique got a wider audience when Daniel Kahneman discussed it favorably in Thinking, Fast and Slow (2011) as a practical way to reduce overconfidence in organizations. It is a close cousin of inversion: instead of asking how to succeed, you ask how you would fail, then avoid that.

How to run a pre-mortem

1. Brief the plan. Make sure everyone understands the decision or project as it currently stands.
2. Set the scene. Say it plainly: “Imagine it is [a date in the future]. We went ahead with this plan, and it was a clear failure.”
3. Write silently. Give everyone a few minutes to list every reason they can think of for the failure, on their own. Silent writing keeps the most senior or loudest voice from steering the list.
4. Share one reason at a time. Go around the room, each person giving one new reason per turn, until the lists are exhausted. Record everything without debate.
5. Rank the risks. Group similar reasons, then pick the few that are both likely and damaging.
6. Change the plan. For each top risk, decide what to do: add a safeguard, a check-in date, a margin of safety, a fallback option, or a change to the plan itself.
7. Assign owners and revisit. Someone watches each top risk. Put a review date on the calendar.

For a solo pre-mortem, do steps 2, 3, 5 and 6 on paper in about fifteen minutes.

3 real-world examples

Business

Say a company plans to launch a subscription product in three months. In the pre-mortem, the engineering lead writes that the billing integration slipped and the launch was delayed. Marketing writes that the price was set without testing and conversion was poor. Support writes that nobody planned for the volume of setup questions. None of these risks were secret, but none had been said in the planning meetings. The team adds a billing milestone, a small pricing test and a support plan before committing to the date.

Personal life

Say you are about to start a big home renovation. You imagine it is six months later and the project went badly. Your reasons: the budget had no buffer, the contractor’s schedule slipped and you were living in a half-finished kitchen, and you made design choices in a rush. You respond by adding a contingency fund, agreeing on a schedule with penalties, and finalizing the design before work starts.

Tech

In a hypothetical case, a team is migrating a database. In the pre-mortem, an engineer imagines the failure: the migration corrupted a subset of records and nobody noticed for a week. That leads to a concrete change: a verification script that compares record counts and checksums before and after, plus a tested rollback plan. Thinking about what happens next, a habit from second-order thinking, also flags that a week of bad data would propagate into reports, so the team plans to pause downstream jobs during the switch.

Common mistakes

• Running it after the decision is locked. If nothing can change, a pre-mortem is theater.
• Letting it become a debate. The sharing round is for listing reasons, not defending the plan. Discussion comes after.
• Skipping the silent writing. Group brainstorming lets the first few voices set the agenda.
• Stopping at the list. The value is in the changes to the plan. A list of risks nobody acts on is just anxiety on paper.
• Only listing external causes. “The market changed” is easy to say. “We misjudged what customers wanted” is more useful.
• Using it to kill every idea. The goal is a stronger plan, not no plan. Every project has failure modes.

Pre-mortem vs post-mortem

Both ask why a project failed. The difference is timing, and timing changes everything about what you can do with the answer.

Use both. The pre-mortem protects this project; the post-mortem (ideally blameless) improves the next one.

The Mentarium take

The pre-mortem is the best return on time of any decision tool we know. An hour of imagined failure regularly saves weeks of real failure, and it costs nothing but a willingness to look at your own plan with suspicion. It is also one of the few techniques that fixes a social problem, not just a thinking problem: it gives people permission to say what they were already worried about.

Not every decision deserves one. That is what the Decision Weight Score (DWS) is for. Rate Reversibility, Impact and Uncertainty, and if the score lands at 7 to 10, the Mentarium Decision Loop calls for the full process: a pre-mortem, a written journal entry and a night’s sleep before deciding. Below that, a quick solo version is usually enough. You can get the score in a minute with the calculator on our tools page.

Inside the Decision Loop (Frame → Map → Stress-test → Decide → Review), the pre-mortem lives in Stress-test, alongside the Bias Radar. For a business decision, the Bias Radar’s list (confirmation bias, planning fallacy, overconfidence bias, survivorship bias, sunk cost fallacy, anchoring bias, bandwagon effect) is a good prompt for the silent-writing step: for each bias, ask how it might have caused the failure you are imagining.

For launches specifically, our Model Stack is Pre-mortem + Pareto principle + Second-order thinking. The pre-mortem finds what could sink you, the Pareto principle keeps the launch focused on the few things that matter, and second-order thinking checks the consequences of your fixes.

If you want a partner to run a pre-mortem with you, the free Mentarium Decision Coach does it inside Claude or ChatGPT as part of the Decision Loop. See the coach to set it up, or the decision-making process guide for the full picture.