── ── Mental model
Critical Thinking
Critical thinking evaluates a conclusion by explicitly testing it against alternative interpretations — the conclusion that survives the most disconfirmation attempts is the one to act on, not the one with the most confirming examples. Operationalized by Richards J. Heuer Jr. (CIA, 1999) as Analysis of Competing Hypotheses (ACH): a matrix marking each evidence-hypothesis pair as Consistent / Inconsistent /…
Run Critical Thinking on a real problem
Bring something you're actually deciding — free, in the browser.
How it works
Run Analysis of Competing Hypotheses (ACH) — Heuer's 8-step procedure. 1. Identify hypotheses. Brainstorm broadly — obvious, contrarian, and 2-3 in between. Generate at least 3 alternatives. 2. List significant evidence for and against each hypothesis — include absence of expected evidence. 3. Prepare the matrix: hypotheses across top, evidence down side. Mark each cell C / I / N/A. Load-bearing step. 4. Refine the matrix. Remove evidence consistent with all hypotheses (no discriminating value). Focus where hypotheses disagree. 5. Draw tentative conclusions. Count Inconsistent marks — the hypothesis with the fewest I marks is the survivor. 6. Sensitivity analysis. If the most-important evidence were wrong, would the conclusion change? Identify linchpin assumptions. 7. Report conclusions — alternatives considered, why rejected, and linchpin assumptions explicitly stated. 8. Set milestones for future observation that may indicate events are taking a different course.
When to use it
- user says 'challenge my thinking', 'play devil's advocate', 'what's the strongest counter-argument', 'ACH', 'analysis of competing hypotheses'
- user needs to evaluate a high-stakes claim or decision with multiple possible interpretations
- user suspects motivated reasoning or a team is converging too fast on one answer
When not to use it
When the decision is routine and reversible, applying a formal method costs more than it returns.
Worked example
ACH at the CIA and the Cuban Missile Crisis Pattern (1962 → 1999)
A worked example. Not folklore — primary-source documented in the CIA's own institutional history.
Install this skill (free, MIT)
npx skills add deciqAI/knowledge-skillsUseful? Star the repo — stars help other builders find it.
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