Alternative Possibility Expansion
Widen decisions with base rates, premortems, and red teams
- Difficulty
- Moderate
- Time to result
- ~days to results
- Steps
- 6
- Confidence
- 98%
Decision makers often imagine a narrow band of outcomes and then coalesce around one optimistic plan. Mauboussin offers three complementary ways to expand the possibility set. Base rates reveal how wide outcomes were for comparable cases. A premortem moves the team into an imagined future where the decision failed and has each person independently document why, allowing junior or dissenting participants to surface risks without first challenging the consensus aloud. Red teaming assigns an adversarial group to attack the strategy as an opponent would. Recording counterfactuals also protects learning after the result, when hindsight bias and creeping determinism make the realized path feel inevitable. Together, these techniques turn vague caution into a repeatable decision review.
Origin
In The Tim Ferriss Show, Mauboussin groups base rates, Gary Klein's premortem, military red teaming, and counterfactual thinking as ways to consider more alternatives.
Core principles
- 01Initial outcome ranges are usually too narrow
- 02Independent downside generation protects minority views
- 03Adversarial attack reveals weaknesses that advocacy misses
- 04Counterfactuals preserve uncertainty after outcomes are known
How to run it
- 1
Capture the initial view
Write down the proposed decision, expected outcome, and current best- and worst-case range. Preserve this before introducing new scenarios.
Pro tip Include probabilities where possible.
Watch out Do not let the team revise its original forecast before it is recorded.
- 2
Open the range with base rates
Compare the proposed range with outcomes from similar cases. Add historically plausible outcomes that the initial analysis omitted.
Pro tip Use the distribution, not just its average.
Watch out Consensus estimates commonly understate the real range.
- 3
Run the premortem
Imagine it is a year later and the decision has turned out horribly. Have every participant independently write why it failed.
Pro tip Collect written answers before discussion so hierarchy does not suppress them.
Watch out A group brainstorm can simply reproduce the existing consensus.
- 4
Red-team the plan
Ask a person or team to attack the strategy and show how it could be defeated. Make the attack concrete rather than requesting general criticism.
Pro tip Give the red team permission and incentives to find real weaknesses.
Watch out A red team that is expected to endorse the plan is ceremonial, not adversarial.
- 5
Rebuild the possibility set
Combine credible base-rate outcomes, premortem causes, and red-team attacks into a revised range. Adjust the plan, safeguards, and probabilities accordingly.
Pro tip Distinguish preventable failure modes from uncertainty that must simply be accepted.
Watch out Do not add scenarios without changing the decision where they are material.
- 6
Preserve counterfactuals
Record the other paths that could occur before the outcome is known. Review the result against that record rather than treating the realized path as inevitable.
Pro tip Separate decision quality from outcome quality.
Watch out Hindsight bias will otherwise make prior uncertainty disappear.
In the wild
A team expects 5% growth, with 8% as the upside and 2% as the downside. Comparable companies reveal a much wider historical range. A premortem then asks each person to explain an imagined failure, and a red team attacks the assumptions behind the plan.
→ The team considers a broader, evidence-based set of outcomes and exposes risks hidden by consensus.
A company develops its defenses and then hires hackers to attack them. The attackers expose vulnerabilities from the adversary's perspective rather than asking the defending team to critique its own work.
→ The organization finds weaknesses before a real attacker exploits them.
Common mistakes
Running the exercise aloud
Independent writing is central to the premortem because it gives dissenting and junior participants room to surface neglected scenarios.
Attacking without authority
A red team cannot expose meaningful weaknesses if status or incentives prevent it from challenging the plan.
Forgetting unrealized paths
Once the outcome occurs, hindsight bias and creeping determinism can erase the alternatives that were genuinely possible.
Is it for you?
Best for
It is best for consequential investments, launches, plans, and strategies where hidden failure modes matter.
Not ideal for
It is not ideal for trivial or readily reversible decisions where the review would cost more than the mistake.
From the transcript
“you pretend like you made the decision. Now you're in the future, say a year from now, and this decisions turned out horribly.”
“Then each person individually and again going back to our concept of diversity each of us individually writes down why this decision turned out so…”
“the blue team defends the strategy, the red team attacks.”
From the episode
#659: Michael Mauboussin — How Great Investors Make Decisions, Harnessing The Wisdom (vs. Madness) of Crowds, Lessons from Race Horses, and More
Michael Mauboussin