Feeling of 'thorough consideration' is a warning signal, not a stop signal
When you feel you have 'thoroughly considered' a decision, treat that feeling as a warning signal requiring additional externalized inventory, because WYSIATI (What You See Is All There Is) creates confidence from narrative coherence rather than completeness.
Why This Is a Rule
Kahneman's WYSIATI (What You See Is All There Is) describes a fundamental cognitive illusion: your brain generates confidence based on the coherence of the story it can construct from available information, not from the completeness of that information. A coherent story built from 30% of the relevant facts feels just as "thorough" as one built from 90%. The feeling of thoroughness is generated by narrative quality, not information quantity.
This means the subjective experience of having "thoroughly considered" a decision is unreliable — and specifically unreliable in the most dangerous direction. The more coherent your internal narrative, the more thoroughly considered the decision feels, even when major factors are missing. You stop looking for information because the story already makes sense. The confidence is real; the completeness is an illusion.
The rule inverts the natural heuristic: instead of treating the feeling of thoroughness as a stop signal ("I've considered everything"), treat it as a warning signal ("My brain just declared this story complete — what am I not seeing?").
When This Fires
- You feel confident about a decision and ready to commit
- A complex decision resolved itself surprisingly quickly or easily
- You can explain your reasoning clearly and it "just makes sense"
- Any high-stakes decision where the feeling of completion arrives before you've done exhaustive analysis
Common Failure Mode
Using the feeling of thoroughness as permission to skip further analysis. "I've thought about this from every angle" is almost always false — it means you've thought about it from every angle that your current context and mental state make accessible, which is a subset of all relevant angles. The feeling is compelling precisely because you can't feel what you haven't considered.
The Protocol
When the feeling of "thoroughly considered" arrives before a consequential decision: (1) Recognize it as a WYSIATI signal, not a completeness signal. (2) Conduct an externalized inventory: write down everything you've considered. (3) Run an absence audit: what perspectives haven't been consulted? What scenarios haven't been modeled? What stakeholders haven't been heard? (4) Ask one person with a different context or role: "What am I probably not seeing?" (5) Only after the external check confirms completeness should you treat the feeling as justified.