Stress-tests predictions by assuming failure and working backward to identify blind spots, tail risks, and overconfidence. Applies Gary Klein's premortem technique to probabilistic forecasting. Use when confidence is high (>80% or <20%), need to identify tail risks and unknown unknowns, want to widen overconfident intervals, or when user mentions premortem, backcasting, what could go wrong, stress test, or black swans.
Core Principle: Invert the problem. Instead of "Will this succeed?", ask "It has failed -- why?"
What would you like to do?
1. Run a Failure Premortem - Assume prediction failed, explain why - For pessimistic predictions (<20%) - View failure through multiple lenses - Find black swans and unknown unknowns - Quantify the adjustment - Deep dive into methodology - Return to main forecasting workflow
Let's stress-test your prediction by imagining it has failed.
Failure Premortem Progress:
- [ ] Step 1: State the prediction and current confidence
- [ ] Step 2: Time travel to failure
- [ ] Step 3: Write the history of failure
- [ ] Step 4: Identify concrete failure modes
- [ ] Step 5: Assess plausibility and adjust
Tell me:
Example: "This startup will reach $10M ARR within 2 years" - Probability: 75%, CI: 60-85%
The Crystal Ball Exercise:
Jump forward to the resolution date. It is now [resolution date]. The event did NOT happen. This is a certainty. Do not argue with it.
How does it feel? Surprising? Expected? Shocking? This emotional response tells you about your true confidence.
Backcasting Narrative: Starting from the failure point, work backward in time. Write the story of how we got here.
Prompts:
Frameworks to consider:
See Failure Mode Taxonomy for comprehensive categories.
Extract specific, actionable failure causes from your narrative.
For each failure mode: (1) What happened, (2) Why it caused failure, (3) How likely it is, (4) Early warning signals
Example:
| Failure Mode | Mechanism | Likelihood | Warning Signals |
|---|---|---|---|
| Key engineer quit | Lost technical leadership, delayed product | 15% | Declining code commits, complaints |
| Competitor launched free tier | Destroyed unit economics | 20% | Hiring spree, beta leaks |
| Regulation passed | Made business model illegal | 5% | Proposed legislation, lobbying |
The Plausibility Test:
Ask yourself:
Quantitative Method: Sum the probabilities of failure modes:
P(failure) = P(mode_1) + P(mode_2) + ... + P(mode_n)
If this sum is greater than 1 - your_current_probability, your probability is too high.
Example: Current success: 75% (implied failure: 25%), Sum of failure modes: 40% Conclusion: Underestimating failure risk by 15%, Adjusted: 60% success
Next: Return to menu or document findings
For pessimistic predictions - assume the unlikely success happened.
Success Premortem Progress:
- [ ] Step 1: State pessimistic prediction (<20%)
- [ ] Step 2: Time travel to success
- [ ] Step 3: Write the history of success
- [ ] Step 4: Identify how you could be wrong
- [ ] Step 5: Assess and adjust upward if needed
Tell me: (1) What low-probability event are you predicting? (2) Why is your confidence so low?
Example: "Fusion energy will be commercialized by 2030" - Probability: 10%, Reasoning: Technical challenges too great
It is now 2030. Fusion energy is commercially available. This happened. It's real. How?
Backcasting the unlikely: What had to happen for this to occur?
Challenge your pessimism:
If success narrative was surprisingly plausible, increase probability.
Next: Return to menu
View the failure through multiple conflicting perspectives.
The dragonfly has compound eyes that see from many angles simultaneously. We simulate this by adopting radically different viewpoints.
Dragonfly Eye Progress:
- [ ] Step 1: The Skeptic (why this will definitely fail)
- [ ] Step 2: The Fanatic (why failure is impossible)
- [ ] Step 3: The Disinterested Observer (neutral analysis)
- [ ] Step 4: Synthesize perspectives
- [ ] Step 5: Extract robust failure modes
Channel the harshest critic. You are a short-seller, a competitor, a pessimist. Why will this DEFINITELY fail?
Be extreme: Assume worst case, highlight every flaw, no charity, no benefit of doubt
Output: List of failure reasons from skeptical view
Channel the strongest believer. You are the founder's mother, a zealot, an optimist. Why is failure IMPOSSIBLE?
Be extreme: Assume best case, highlight every strength, maximum charity and optimism
Output: List of success reasons from optimistic view
Channel a neutral analyst. You have no stake in the outcome. You're running a simulation, analyzing data dispassionately.
Be analytical: No emotional investment, pure statistical reasoning, reference class thinking
Output: Balanced probability estimate with reasoning
Find the overlap: Which failure modes appeared in ALL THREE perspectives?
These are your robust failure modes - the ones most likely to actually happen.
The synthesis:
| Failure Mode | Skeptic | Fanatic | Observer | Robust? |
|---|---|---|---|---|
| Market too small | Definitely | Debatable | Base rate suggests yes | YES |
| Execution risk | Definitely | No way | 50/50 | Maybe |
| Tech won't scale | Definitely | Already solved | Unknown | Investigate |
Focus adjustment on the robust failures that survived all perspectives.
Next: Return to menu
Find the black swans and unknown unknowns.
Tail Risk Identification Progress:
- [ ] Step 1: Define what counts as "tail risk"
- [ ] Step 2: Systematic enumeration
- [ ] Step 3: Impact × Probability matrix
- [ ] Step 4: Set kill criteria
- [ ] Step 5: Monitor signposts
Criteria: Low probability (<5%), High impact (would completely change outcome), Outside normal planning, Often exogenous shocks
Examples: Pandemic, war, financial crisis, regulatory ban, key person death, natural disaster, technological disruption
Use the PESTLE framework for comprehensive coverage:
For each category, ask: "What low-probability event would kill this prediction?"
See Failure Mode Taxonomy for detailed categories.
Plot your tail risks:
High Impact
│
│ [Pandemic] [Key Founder Dies]
│
│
│ [Recession] [Competitor Emerges]
│
└─────────────────────────────────────→ Probability
Low High
Focus on: High impact, even if very low probability
For each major tail risk, define the "kill criterion":
Format: "If [event X] happens, probability drops to [Y]%"
Examples:
Why this matters: You now have clear indicators to watch
For each kill criterion, identify early warning signals:
| Kill Criterion | Warning Signals | Check Frequency |
|---|---|---|
| FDA rejection | Phase 2 trial results, FDA feedback | Monthly |
| Engineer quit | Code velocity, satisfaction surveys | Weekly |
| Competitor launch | Hiring spree, beta leaks, patents | Monthly |
| Regulation | Proposed bills, lobbying, hearings | Quarterly |
Setup monitoring: Calendar reminders, news alerts, automated tracking
Next: Return to menu
Quantify how much the premortem should change your bounds.
Confidence Interval Adjustment Progress:
- [ ] Step 1: State current CI
- [ ] Step 2: Evaluate premortem findings
- [ ] Step 3: Calculate width adjustment
- [ ] Step 4: Set new bounds
- [ ] Step 5: Document reasoning
Current confidence interval: Lower bound: __%, Upper bound: __%, Width: ___ percentage points
Score your premortem on these dimensions (1-5 each):
Total score: __ / 20
Adjustment formula:
Width multiplier = 1 + (Score / 20)
Examples:
Current width: ___ points, Adjusted width: Current × Multiplier = ___ points
Method: Symmetric widening around current estimate
New lower = Current estimate - (Adjusted width / 2)
New upper = Current estimate + (Adjusted width / 2)
Example: Current: 70%, CI: 60-80% (width = 20), Score: 12/20, Multiplier: 1.6, New width: 32, New CI: 54-86%
Record: (1) What failure modes drove the adjustment, (2) Which perspective was most revealing, (3) What unknown unknowns were discovered, (4) What monitoring you'll do going forward
Next: Return to menu
Deep dive into the methodology.
📄 Premortem Principles - Why humans are overconfident, hindsight bias and outcome bias, the power of inversion, research on premortem effectiveness
📄 Backcasting Method - Structured backcasting process, temporal reasoning techniques, causal chain construction, narrative vs quantitative backcasting
📄 Failure Mode Taxonomy - Comprehensive failure categories, internal vs external failures, preventable vs unpreventable, PESTLE framework for tail risks, kill criteria templates
Next: Return to menu
Assume your prediction has failed, write the history of how, and use that to identify blind spots and adjust confidence.
scout-mindset-bias-check to validate adjustmentsbayesian-reasoning-calibration for quantitative updates📁 resources/
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