Premortem

Attribution: This skill is adapted from @itsolelehmann's premortem AI-skill formulation, posted to X on 2026-05-02 (source thread) as part of his Skillstack work. The underlying method is Gary Klein's premortem technique (Harvard Business Review, 2007), popularized by Daniel Kahneman in Thinking, Fast and Slow. This version is bundled with the Broomva Stack's strategy-skills (Layer 7 — Strategy & Decision Intelligence). Distinct from the bundled pre-mortem skill, which uses a structured-scoring approach; this one uses parallel sub-agent deep-dives and produces an HTML report.

A premortem is the opposite of a postmortem. Instead of figuring out what went wrong after something fails, you imagine it already failed and figure out why before you start.

The method comes from psychologist Gary Klein. He published it in Harvard Business Review. Daniel Kahneman (the Nobel Prize-winning psychologist behind "Thinking, Fast and Slow") called it his single most valuable decision-making technique. Google, Goldman Sachs, and Procter & Gamble all use it before major decisions.

The core insight: when you ask people "what could go wrong?" they give you cautious, hedged answers. When you say "this already failed, tell me why," their brains switch into narrative mode and generate way more specific, creative, honest reasons. Researchers at Wharton and Cornell called this "prospective hindsight" and found it significantly increases the ability to identify causes of future outcomes.

The reason this matters for AI-assisted decisions: Claude defaults to agreeable, optimistic responses. If you ask "is this a good plan?" it will find reasons to say yes. The premortem breaks this pattern by forcing the frame into "this is dead, explain how it died." Claude stops looking for reasons your plan will work and starts explaining how it fell apart.

when to run a premortem