MENTAL MODEL · M1320

Double Crux

StructuremediumCritical Thinking

Included

Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

In a debate, look for a specific factual point such that if it were proven true, you would change your position; if it were proven false, the other person would change theirs. This point is the 'double crux.'

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Efficient debate. Don't argue to win. Directly ask the other person: 'What evidence would change your mind?' If they say 'nothing could change my mind,' then stop the discussion immediately, because it is no longer a debate but preaching.

anchor

Anchor fast decisions

Derived from the rationality training technique 'double crux': instead of directly arguing, each side identifies the key argument (crux) such that 'if my belief on this point changed, my judgment on the original issue would also change,' then seeks a common, testable foundation to advance consensus.

MINIMUM ACTION

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Practice this model in one real situation:

Each side lists the core premises supporting their position
identify the key premise whose change would alter the conclusion
see if both cruxes point to the same testable question
discuss evidence on the crux rather than surface positions.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

link
rationality.orghttps://rationality.org/resources/updates/2016/double-cruxZH · Explicit
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