How to Run a Pre-Mortem: A Facilitation Guide
A pre-mortem (Gary Klein, Harvard Business Review, 2007) asks the team to imagine the plan has already failed and write down why — prospective hindsight raises the number and specificity of the risks people surface. The problem it solves is social, not analytical: people know the risks and will not say them in front of the sponsor. To run one in 60–90 minutes on Argumentree: frame the plan as a root claim (not a question); have each participant silently add failure causes as independent con-arguments; optionally sweep for additional machine-suggested failure modes, which stay visibly labelled and can be cross-examined because AI-authored arguments answer questions automatically; interrogate causes through Q&A chains (four turns, challenger and author); stress-test causes through Review chains — group critique is many parallel chains on one cause, not one shared round; merge duplicates through Compromise chains on the record; rate every cause and read the spread, not just the mean — high variance means the room disagrees, which is itself the finding; and attach mitigations as counter-arguments under each cause, where a con-of-a-con supports the plan. Honest limits: tooling does not create psychological safety, ratings are a single labelled value rather than a probability-impact matrix, chains are four turns then complete, and the pre-mortem surfaces and prioritises — it does not decide.
Gary Klein's pre-mortem tells the room the plan has already failed and asks why — because prospective hindsight surfaces risks that politeness suppresses. Run it so every risk stays attached to the decision:
- Frame the plan as a claim, so things can attack it — then ten silent minutes of independent failure-writing
- Interrogate and stress-test what surfaced through Q&A and Review chains — four-turn dialogues with each risk's author, in parallel
- Rate every cause and read the spread — high variance means the room disagrees, which is itself the finding
- Mitigations are counter-arguments: a con of the cause — and a con-of-a-con supports the plan
The retro that came too late
Twelve months from now, you are sitting in the retrospective for the plan you are about to approve. The launch missed, the numbers are bad, and the room is doing the thing rooms do in retros: explaining, fluently and in detail, why it was always going to go wrong. The vendor dependency everyone privately doubted. The hiring assumption nobody believed. The integration risk that one engineer mentioned once, quietly, and never again.
Here is the uncomfortable part: most of that knowledge exists today, in the heads of the people who will sit in that retro. Your team is not failing to see the risks. It is failing to say them — because the plan has a sponsor, the sponsor is in the room, and nobody builds a career on being the person who listed reasons the boss's plan will fail.
The pre-mortem is the ritual built for exactly this. Gary Klein described it in Harvard Business Review in 2007: tell the room the plan has already failed, twelve months out, and ask everyone to write down why. The tense change does real work — research on prospective hindsight finds that imagining an outcome as certain, rather than merely possible, increases the number and specificity of causes people generate. And the framing does social work too: you are no longer criticising the sponsor's plan; you are explaining a fictional past. Everyone is suddenly allowed to know what they know.
Why people already knew
It is worth being precise about what the pre-mortem fixes, because it is not an analysis technique. The failure modes it surfaces were almost always known to someone before the decision. What blocked them is the standard machinery of group deference: dissent is socially expensive, early opinions anchor later ones, and the person with the decisive worry is often the most junior voice on the call. Our pieces on structured disagreement and steelmanning walk that machinery in detail — the pre-mortem is the applied countermeasure.
That is also why running it with the right mechanics matters more than running it with enthusiasm. The two load-bearing properties are independence — everyone writes before anyone sees anyone else's causes — and attachment — every cause stays connected to the plan it threatens, with an author, so it can be questioned, challenged, and mitigated rather than photographed on a whiteboard and forgotten.
What you need
An Argumentree discussion (any plan works — the free tier is enough to run your first pre-mortem), the plan's owner in the room, and 60–90 minutes. Participants join from anywhere; the ritual works synchronously or spread across a day.
Step 1: Frame the plan as a claim
Create the discussion with the plan as its root argument — stated as a committed claim, not a question: "We will ship X to segment Y by Q2." The phrasing matters. A question ("should we ship X?") invites debate about whether; a claim creates a thing that failure causes can attack. One sentence, dated, owned by the plan's sponsor.
Then deliver Klein's framing to the room, verbatim if you like: "It is twelve months from now. This plan failed — badly. Take ten minutes, alone, and write down every reason why."
- ✓Root claim created — the plan as one committed sentence, authored by its sponsor. Checkpoint: it reads as a claim something can attack, not a question.
Step 2: The silent ten minutes
Each participant now adds failure causes as con-arguments under the plan — independently. This is where the tool earns its place over the whiteboard: a cause is only visible to others once submitted, so nobody anchors on the first confident voice, and nobody softens their risk after seeing the sponsor's face. Ask for at least three causes each, written as specific claims ("the SSO integration slips past the pilot date"), not categories ("technical risk").
Optionally, run an AI sweep alongside: have additional failure modes generated from multiple models. They arrive visibly labelled as machine-suggested — provenance is stamped on every argument — so the room can always tell an engineer's lived worry from a model's pattern-match. Keep them separate in your reading, too: the AI widens the space of candidate risks; it does not know your organization.
- ✓Silent generation complete — everyone submitted independently. Checkpoint: ≥3 causes per participant; nobody edited anyone; AI causes (if any) visibly labelled.
When the AI sweep hurts
Run the silent human round first, machine sweep second. If the model's fluent phrasing lands before people write, it anchors them — you get well-worded generic risks instead of the specific ones only your team knows. The sweep is a net for what humans missed, never the opening act.
Step 3: Interrogate what surfaced
Now the room reads the tree — and instead of an open discussion where the loudest reader wins, the causes get worked through three structured moves, each a four-turn dialogue between a challenger and the cause's author:
Q&A chain — understand it
Open a Q&A chain on any cause you cannot evaluate: "what fails first, and how would we notice?" The author answers, you follow up, they answer again — then it completes. No cause should be left that nobody understands.
Review chain — stress-test it
Think a cause is overstated (or understated)? Open a Review chain: your evaluation, the author's response, follow-up, response. The exchange survives as the record of the challenge.
Compromise chain — merge duplicates
Two people wrote the same risk differently? Propose the combined wording to the other author. Consolidation happens on the record — not by a facilitator silently deleting a sticky note.
Group critique = parallel chains
There is no "start critique round" button, by design: group critique is N people each opening their own chain on the same cause, and the author answering each. Every objection stays attributable and answered.
One feature is worth calling out, because it changes what the AI sweep is worth: machine-suggested causes answer back. An argument authored by a model auto-responds in its chains — routed to the same model that wrote it — so you can cross-examine a machine-suggested failure mode and get a substantive reply immediately. That is the concrete answer to "why not just ask a chatbot for a risk list": a list cannot be questioned.
Step 4: Rate, and read the spread
Every participant rates every cause — one rating each, a value with a label. Sort by the distribution, and then do the thing most rooms skip: look at the spread, not just the mean. A cause everyone rates 8 is a priority. A cause half the room rates 9 and half rates 2 is something better: a genuine disagreement about how the world works, surfaced and named. Those splits are usually the most valuable finding of the whole session.
- ✓Prioritisation done — causes rated by everyone. Checkpoint: top causes identified; high-variance causes flagged as disagreements, not averaged into the middle.
The question to ask the room
Which cause did nobody rate the same way? That split is where your team's models of reality diverge — and where the next conversation should start.
Step 5: Mitigations as counter-arguments
For each top cause, add mitigations — and here the tree does something a list cannot. A mitigation is added as a con of the cause: an argument attacking the failure mode. And because pro/con is relative to the parent, a con-of-a-con supports the plan — the structure encodes the logic natively. Each mitigation has an author, and the author is the owner.
This is the moment the pre-mortem usually dies in whiteboard form: risks get listed, heads nod, nothing gets an owner. Here the checkpoint is structural — a top cause without a mitigation hanging under it is visibly naked.
- ✓Mitigations attached — every top cause carries at least one counter-argument with a named author. Checkpoint: no top-rated cause left bare.
What you still have in six months
The artifact is the point. Six months from now, when something goes wrong and someone asks "did we consider this?", the answer is one search away: the plan, every objection raised against it, who raised each one, the challenges each survived, and the mitigation that was (or was not) attached. A photographed whiteboard cannot answer that question; this can — it is a working instance of the decision quality chain, built in ninety minutes.
Honest limitations
- ✗Tooling does not create psychological safety. Independent submission removes the anchoring problem; it does not remove a manager who punishes dissent. If people fear the sponsor, fix that first.
- ✗AI-generated risks are prompts for thought, not a risk register. They are labelled for exactly that reason. A cause nobody will own is not a finding.
- ✗Ratings are a single labelled value, not a probability × impact matrix. If you need a formal risk matrix, export and build it elsewhere — do not pretend the rating is one.
- ✗A chain is four turns, then complete. It is a structured exchange, not an endless thread. If a disagreement needs more, it needs a meeting.
- ✗A pre-mortem does not decide anything. It surfaces and prioritises; the decision — and the courage to change the plan — is still yours.
Practical lessons from running these
- ✓Time-box the silence hard. Ten minutes, announced, enforced. The value is in the independence; the moment discussion starts, it stops accumulating.
- ✓Ask for specific sentences, not categories. "Integration risk" prioritises nothing; "the SSO integration slips past the pilot date" can be challenged, rated and mitigated.
- ✓The sponsor writes too. Nothing licenses honesty like the plan's owner contributing three failure modes of their own — first.
- ✓Close the loop in the next planning session. Reopen the tree, check which mitigations happened, and rate the causes again. The second pass takes twenty minutes and is where the ritual compounds.
Back to the retro
Return to that twelve-months-out retrospective. Either version of it can happen. In one, the room fluently explains a failure it quietly predicted, and the record shows nothing. In the other, the retro opens with the pre-mortem tree: here is what we said could go wrong, here is what we did about it, here is the one we missed. The second retro is shorter, kinder, and the only one that makes the next plan better. Ninety minutes, this week, buys it.
Sources & further reading
- Klein, G. (2007). Performing a Project Premortem. Harvard Business Review, September 2007.The canonical two-page description of the ritual and the prospective-hindsight rationale.
- Mitchell, D. J., Russo, J. E., & Pennington, N. (1989). Back to the future: Temporal perspective in the explanation of events. Journal of Behavioral Decision Making, 2(1).The prospective-hindsight research behind the tense change: imagining an outcome as certain increases the number and specificity of generated causes.
- Klein, G., Koller, T., & Lovallo, D. (2019). Bias Busters: Premortems — being smart at the start. McKinsey Quarterly.The pre-mortem placed among debiasing practices for strategic decisions.
Frequently Asked Questions
What is a pre-mortem and how is it different from a risk assessment?
A pre-mortem, described by Gary Klein in Harvard Business Review (2007), asks a team to imagine the plan has already failed and write down why. The tense change matters: prospective-hindsight research finds that imagining an outcome as certain rather than possible increases the number and specificity of causes people generate. It differs from a standard risk assessment in what it fixes — the problem is social, not analytical. People usually know the risks; the pre-mortem's fictional-past framing makes it safe to say them in front of the plan's sponsor.
How long does a pre-mortem take to run?
60–90 minutes for the core ritual: a few minutes to frame the plan as a committed claim, ten silent minutes of independent failure-writing, roughly half an hour of interrogating and stress-testing the surfaced causes, ten minutes of rating, and the remainder attaching mitigations with named owners. Run asynchronously, the same steps spread comfortably across a day, with the silent-writing window time-boxed.
How do you run a pre-mortem remotely or asynchronously?
The ritual is naturally async-friendly because its core requirement is independence, not co-presence. Frame the plan as the root claim, give participants a submission window in which each adds failure causes as con-arguments without seeing others' input, then open the tree for Q&A and Review chains — which are four-turn dialogues that work across time zones by construction. Rate within a second window and read the distribution together. The only synchronous moment worth keeping is the final read-out of the high-variance causes.
Should AI be used to generate pre-mortem risks?
As a second pass, yes; as the opening act, no. Machine-generated failure modes widen the candidate space and arrive visibly labelled, so they are never confused with a team member's lived worry — and because AI-authored arguments answer questions automatically, a machine-suggested risk can be cross-examined rather than just read. But run the silent human round first: fluent machine phrasing shown early anchors people, and you get generic well-worded risks instead of the specific ones only your team knows.
What do you do with pre-mortem results?
Three things. Prioritise by the rating distribution — and treat high-variance causes (half the room says 9, half says 2) as genuine disagreements to resolve, not noise to average away. Attach a mitigation with a named owner under every top cause — in an argument tree, a mitigation is a con of the cause, and a con-of-a-con supports the plan. And keep the tree as the record: in six months, "did we consider this?" is answered by a search, not by memory.
Does a pre-mortem actually change the decision?
Sometimes — and honestly, that is not its main job. The pre-mortem surfaces and prioritises; it does not decide. Its measurable value is that risks that would have stayed unsaid get said, get owners, and get mitigations before commitment, and that the record survives. Whether the plan then changes is a judgment call for the decision-maker — who now makes it knowing what the team actually thinks.
Run your first pre-mortem this week.
Frame the plan, open the silent window, and let the risks your team already knows finally get said — attached to the decision, with owners.
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