This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
The tendency to devalue a proposal or idea simply because it originated from an antagonist or opponent. A peace offer from an enemy is assumed to be a trap; the same offer from an ally would be welcomed.
When it shows up
Negotiations with opponents. Any proposal received from a source you distrust. Evaluating advice from an ideological opposite. Rejecting an offer because of who is making it.
Failure mode
The merit of a proposal is discounted purely because of its source. The same proposal from a trusted source would be accepted. The evaluator cannot separate the content from its origin.
Countermeasure
Write the proposal's terms out without the source attached. Evaluate the terms in isolation. Then re-attach the source and notice what changed in your rating. That delta is the reactive devaluation.
Related traps
Also connected in the map2 more, locked
Credit & first seen
DiscoveredIdentified by Lee Ross and Constance Stillinger in research on conflict negotiation (1991).
Also revealed
Entry #79 of 631 in The Lexicon · see the full Lexicon