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From grimoire
Solves problems by reasoning backward from failure — enumerates causes of failure, scores them, then eliminates them. Useful for stress-testing plans and surfacing hidden risks.
npx claudepluginhub jeffreytse/grimoire --plugin grimoireHow this skill is triggered — by the user, by Claude, or both
Slash command
/grimoire:apply-inversionThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Solve problems by asking "what would cause failure?" then eliminating those causes — rather than asking "how do we succeed?" and hoping to avoid obstacles along the way.
Enumerates failure modes by inverting goals to uncover hidden risks during planning. Useful when optimism may obscure failure paths.
Performs pre-mortem analysis imagining catastrophic failures for uncommitted plans or existing systems via parallel lenses, yielding prioritized risk registers with early warnings.
Performs pre-mortem analysis assuming total failure to identify specific risks, leading indicators, and circuit breakers across technical, organizational, external, temporal, and assumption categories. For project plans, architecture, and launches.
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Solve problems by asking "what would cause failure?" then eliminating those causes — rather than asking "how do we succeed?" and hoping to avoid obstacles along the way.
Adopted by: Charlie Munger and Warren Buffett (Berkshire Hathaway), mathematicians (Carl Jacobi's dictum: "Invert, always invert"), and standard curriculum in decision-making programs at top business schools including Harvard Business School and Stanford GSB. Impact: Munger attributes inversion as a primary driver of Berkshire's 50-year compounding record — it systematically surfaces risks that forward-thinking misses. In mathematics, Jacobi's inversion principle solved problems that direct approaches failed to crack for decades. Inversion is taught as a core mental model in Shane Parrish's Farnam Street curriculum, used by hundreds of thousands of practitioners. Why best: Forward planning optimism bias is a documented cognitive failure mode: teams overestimate success probability and underestimate failure modes. Inversion bypasses this bias by starting from the failure endpoint and working backward, forcing explicit enumeration of every path to disaster. Removing failure paths is often more tractable than constructing success paths.
Sources: Charlie Munger "Poor Charlie's Almanack" (2005); Carl Jacobi "Fundamenta Nova Theoriae" (1829); Kahneman "Thinking, Fast and Slow" §24 on planning fallacy
Project launch: Goal: "ship MVP by April 15." Inversion: "What guarantees we miss April 15?" Causes: scope creep, no prioritized backlog, single point of failure on key engineer, no staging environment. Countermeasures: scope freeze, weekly backlog review, cross-training, staging setup in week 1.
Investment decision: Goal: "this acquisition creates value." Inversion: "What guarantees this acquisition destroys value?" Causes: culture mismatch, key talent departure, integration costs exceed projections, customer churn post-announcement. Each cause gets a due-diligence check or integration safeguard.