Most business plans are written in a mood of optimism. Everyone in the room wants the launch, the hire or the new product to work, so the plan describes how it will work. The pre-mortem flips that habit: you imagine the plan has already failed and ask what went wrong. This guide shows how to run one, with a few quotes on planning, change and decisions to keep you honest.
What a pre-mortem is
A pre-mortem is a planning exercise in which a team imagines that a project or organization has already failed, then works backward to identify what could have caused that failure. According to the Wikipedia entry on the technique, it is meant to counter groupthink and biases such as overconfidence and the planning fallacy. It is described there in a 2007 Harvard Business Review article by Gary Klein titled "Performing a Project Premortem," and it formalizes an older idea called prospective hindsight, where people look back from the future to spot problems.
The name comes from the medical post-mortem, which asks why a patient died after the fact. A pre-mortem asks the same question while the patient is still alive and something can be done about it. That small change in timing is the whole point.
Why imagining failure works better than asking for risks
If you ask a team, "What could go wrong?", people tend to offer polite, safe answers. Nobody wants to be the person who dampens the mood. If you say instead, "It is a year from now and this failed badly. Why?", the failure is treated as a fact, and explaining it becomes a creative puzzle rather than a criticism of the plan or its owner.
This matters because change rarely arrives on schedule. Peter Drucker put the underlying problem plainly:
The only thing we know about the future is that it is going to be different. — Peter Drucker
Take that literally. If the future will differ from your forecast, the useful question is not whether your plan is right but where it is most likely to be wrong. A pre-mortem is a cheap way to find those weak points before money, reputation and morale are committed.
How to run a 45-minute pre-mortem
Step 1: Set the scene
Gather the people who will actually do the work, plus at least one person who is not emotionally invested in it. Describe the plan in two or three sentences so everyone is thinking about the same thing. Then state the premise clearly: "Assume it is twelve months from now. The project has failed. Not a little. Badly."
Step 2: Write silently
Give everyone five to ten minutes to write down reasons for the failure on their own. Working alone first prevents the most senior or most talkative person from steering the group. Ask for specifics: not "poor communication" but "the sales team did not learn about the pricing change until customers called."
Step 3: Collect and cluster
Go around the room and have each person read one reason at a time until all of them are on a board. Group similar items. You will usually see three to six clusters, such as customer demand, cash, key people, timing, dependencies on other teams and quality.
Step 4: Rate each cluster
For each cluster, score how likely it is and how damaging it would be. The Wikipedia summary describes the same sequence: imagine failure, work backward to identify threats, assess each threat's magnitude and likelihood, and take preventive action. A simple low, medium and high scale is enough.
Step 5: Change the plan
This is the step teams skip. Pick the top three threats and decide what you will change now: add a checkpoint, run a small test, hire a backup, set a spending limit, or delay a launch. Assign each change to a named person with a date. A pre-mortem that ends in a list of worries and no edits to the plan has only made everyone more anxious.
Planning is the point, not the plan
There is an old military saying that Dwight D. Eisenhower repeated in a 1957 speech to the National Defense Executive Reserve Conference. As documented by Quote Investigator, he said he had heard it long ago in the Army:
Plans are worthless, but planning is everything. — Dwight D. Eisenhower
Eisenhower told a story about army training maps to show that emergencies are, by definition, unexpected, so the real events never match the written plan. The thinking you do while planning is what prepares you to adapt. A pre-mortem is a concentrated dose of exactly that thinking. After your session, the document matters less than the fact that your team has already rehearsed several ways things could go wrong and has some answers ready.
Make decisions while they are still cheap
Pre-mortems are most valuable early, when changing course costs little. Drucker noted a related principle about timing in his book on management:
One has to make a decision when a condition is likely to degenerate if nothing is done. — Peter Drucker
Read it as permission to act on a warning sign you found in the pre-mortem even though nothing has visibly gone wrong yet. If your cluster on cash flow rates high on both likelihood and damage, do not wait for the bank balance to confirm it. Cut a cost, line up credit or slow hiring now.
Decisions exist only in the present. — Peter Drucker
The pre-mortem is a tool for the present: you look at the future, but the output is a decision made today about what to do this week. Close every session by writing down the first action and who owns it.
Common mistakes to avoid
- Letting the boss speak first. Senior opinions anchor the room. Have the most senior person write silently like everyone else and speak last.
- Treating it as a blame session. The goal is to find weak points in the plan, not in people. Keep the language about causes, not culprits.
- Doing it too late. Run it before you commit budget, announce dates or sign contracts, while changes are still cheap.
- Collecting risks without ranking them. A list of thirty worries is paralyzing. Rank them and handle the top three.
- Ignoring the result. If nothing in the plan changed afterward, the exercise was theater.
One honest caveat, also noted on the Wikipedia page: because a pre-mortem assumes failure, it may surface threats that are not actually real. That is not a reason to skip it. It is a reason to rate the threats and focus on the likely and damaging ones rather than reacting to every possibility.
A worked example
Imagine a three-person agency planning to launch a monthly subscription service. In the pre-mortem, the team writes down reasons it failed: the first ten customers cancelled because onboarding was confusing, one founder burned out handling support, the price was set from a guess rather than a conversation with buyers, and a large client paid late and cash ran short. Clustered, these become onboarding, workload, pricing and cash.
The team then changes the plan. It will interview five prospective customers about price before launch, write a simple onboarding checklist and test it with two pilot clients, set a rule that no single client may exceed a third of revenue, and agree on a support rota so one person does not carry it all. None of these changes needed a bigger budget. They only needed someone to imagine the failure first.
Putting quotes to work
Pin one line where your team plans. Drucker's reminder that the future will be different is a good prompt at the start of a session. Eisenhower's line about planning is a good one to read at the end, when people are tempted to treat the finished document as the achievement. The value is in the thinking, and the thinking continues after launch, whenever new information changes the picture.
You can also repeat the exercise at milestones. A pre-mortem at kickoff catches design flaws. A second one at the halfway point catches execution flaws, because by then you know things you could not know at the start. Teams that do this regularly tend to get better at naming problems early, which is the real skill underneath the technique.
Your next step
Choose one decision you are about to make this month: a launch, a hire, a price change, a partnership. Schedule 45 minutes with the people involved. Write the sentence "It is a year from now and this failed" on a whiteboard, and start writing. Then change something in the plan before you leave the room.