Heuer's Analysis of Competing Hypotheses instructs analysts to disprove hypotheses rather than prove them

Richards J. Heuer Jr.'s Psychology of Intelligence Analysis (CIA, Center for the Study of Intelligence, 1999) formalizes Analysis of Competing Hypotheses (ACH) as an eight-step matrix procedure. Its purpose is to counteract a specific, documented failure of human reasoning: analysts who "focus mainly on trying to confirm one hypothesis they think is probably true." ACH inverts that instinct. Its fifth step reads: "Draw tentative conclusions about the relative likelihood of each hypothesis. Proceed by trying to disprove hypotheses rather than prove them" (p. 85 of the CREST-hosted text).

The move is deliberately falsificationist: rather than accumulating evidence for a favored conclusion, the analyst enumerates the full set of candidate hypotheses and works to eliminate them, so the hypothesis that survives the most disconfirming evidence — not the one with the most supporting evidence — is judged most likely. This is the procedural antidote to confirmation bias, the same bias that let a decisive refutation sit unretracted in the Yellow Rain episode.