# Premortem Principles ## The Psychology of Overconfidence ### Why We're Systematically Overconfident **The Planning Fallacy:** - We focus on best-case scenarios - We ignore historical delays and failures - We assume "our case is different" - We underestimate Murphy's Law **Research:** - 90% of projects run over budget - 70% of projects run late - Yet 80% of project managers predict on-time completion **The fix:** Premortem forces you to imagine failure has already happened. --- ## Hindsight Bias ### The "I Knew It All Along" Effect **What it is:** After an outcome occurs, we believe we "always knew" it would happen. **Example:** - Before 2008 crash: "Housing is safe" - After 2008 crash: "The signs were obvious" **Problem for forecasting:** If we think outcomes were predictable in hindsight, we'll be overconfident going forward. **The premortem fix:** By forcing yourself into "hindsight mode" BEFORE the outcome, you: 1. Generate the warning signs you would have seen 2. Realize how many ways things could go wrong 3. Reduce overconfidence --- ## The Power of Inversion ### Solving Problems Backward **Charlie Munger:** > "Invert, always invert. Many hard problems are best solved backward." **In forecasting:** - Hard: "Will this succeed?" (requires imagining all paths to success) - Easier: "It failed - why?" (failure modes are more concrete) **Why this works:** - Failure modes are finite and enumerable - Success paths are infinite and vague - Humans are better at imagining concrete negatives than abstract positives --- ## Research on Premortem Effectiveness ### Gary Klein's Studies **Original research:** - Teams that did premortems identified 30% more risks - Risks identified were more specific and actionable - Teams adjusted plans proactively **Key finding:** > "Prospective hindsight" (imagining an event has happened) improves recall by 30% --- ### Kahneman's Endorsement **Daniel Kahneman:** > "The premortem is the single best debiasing technique I know." **Why it works:** 1. **Legitimizes doubt** - In group settings, dissent is hard. Premortem makes it safe. 2. **Concrete > Abstract** - "Identify risks" is vague. "Explain the failure" is concrete. 3. **Defeats groupthink** - Forces even optimists to imagine failure. --- ## Outcome Bias ### Judging Decisions by Results, Not Process **What it is:** We judge the quality of a decision based on its outcome, not the process. **Example:** - Drunk driver gets home safely → "It was fine" - Sober driver has accident → "Bad decision to drive" **Reality:** Quality of decision ≠ Quality of outcome (because of randomness) **For forecasting:** A 90% prediction that fails doesn't mean the forecast was bad (10% events happen 10% of the time). **The premortem fix:** By imagining failure BEFORE it happens, you evaluate the decision process independent of outcome. --- ## When Premortems Work Best ### High-Confidence Predictions **Use when:** - Your probability is >80% or <20% - You feel very certain - Confidence intervals are narrow **Why:** These are the predictions most likely to be overconfident. --- ### Team Forecasting **Use when:** - Multiple people are making predictions - Groupthink is a risk - Dissent is being suppressed **Why:** Premortems legitimize expressing doubts without seeming disloyal. --- ### Important Decisions **Use when:** - Stakes are high - Irreversible commitments - Significant resource allocation **Why:** Worth the time investment to reduce overconfidence. --- ## When Premortems Don't Help ### Already Uncertain **Skip if:** - Your probability is ~50% - Confidence intervals are already wide - You're confused, not confident **Why:** You don't need a premortem to tell you you're uncertain. --- ### Trivial Predictions **Skip if:** - Low stakes - Easily reversible - Not worth the time **Why:** Premortems take effort; save them for important forecasts. --- ## The Premortem vs Other Techniques ### Premortem vs Red Teaming **Red Teaming:** - Adversarial: Find flaws in the plan - Focus: Attack the strategy - Mindset: "How do we defeat this?" **Premortem:** - Temporal: Failure has occurred - Focus: Understand what happened - Mindset: "What led to this outcome?" **Use both:** Red team attacks the plan, premortem explains the failure. --- ### Premortem vs Scenario Planning **Scenario Planning:** - Multiple futures: Good, bad, likely - Branching paths - Strategies for each scenario **Premortem:** - Single future: Failure has occurred - Backward path - Identify risks to avoid **Use both:** Scenario planning explores, premortem stress-tests. --- ### Premortem vs Risk Register **Risk Register:** - List of identified risks - Probability and impact scores - Mitigation strategies **Premortem:** - Narrative of failure - Causal chains - Discover unknown unknowns **Use both:** Premortem feeds into risk register. --- ## Cognitive Mechanisms ### Why Premortems Defeat Overconfidence **1. Prospective Hindsight** Imagining an event has occurred improves memory access by 30%. **2. Permission to Doubt** Social license to express skepticism without seeming negative. **3. Concrete Failure Modes** Abstract "risks" become specific "this happened, then this, then this." **4. Temporal Distancing** Viewing from the future reduces emotional attachment to current plan. **5. Narrative Construction** Building a story forces causal reasoning, revealing gaps. --- ## Common Objections ### "This is too negative!" **Response:** Pessimism during planning prevents failure during execution. **Reframe:** Not negative - realistic. You're not hoping for failure, you're preparing for it. --- ### "We don't have time for this." **Response:** - Premortem: 30 minutes - Recovering from preventable failure: Months/years **Math:** If premortem prevents 10% of failures, ROI is massive. --- ### "Our case really is different!" **Response:** Maybe. But the premortem will reveal HOW it's different, not just assert it. **Test:** If the premortem reveals nothing new, you were right. If it reveals risks, you weren't. --- ## Practical Takeaways 1. **Use for high-confidence predictions** - When you feel certain 2. **Legitimate skepticism** - Makes doubt socially acceptable 3. **Concrete failure modes** - Forces specific risks, not vague worries 4. **Widen confidence intervals** - Adjust based on plausibility of failure narrative 5. **Set kill criteria** - Know what would change your mind 6. **Monitor signposts** - Track early warning signals **The Rule:** > If you can easily write a plausible failure narrative, your confidence is too high. --- **Return to:** [Main Skill](../SKILL.md#interactive-menu)