Source-trusting alone can split a community into stable opposing epistemic camps

Evidence

This small change to the model radically alters the outcomes. Now, instead of steadily trending toward a consensus, either right or wrong, scientists regularly split into polarized groups holding different beliefs, with each side trusting the evidence of only those who already agree with them. Initially, scientists’ beliefs are randomly distributed throughout the network. Most scientists begin by listening to, and updating on the basis of, the evidence produced by most other scientists. But over time, groups of scientists begin to pull apart until eventually you have two groups with opposite beliefs who do not listen to each other at all. … Such a model does not capture the moral anger we see in the case of chronic Lyme, or in political polarization. But we do see that under fairly minimal assumptions, entire scientific communities can split into two groups with opposite beliefs. Even worse, this sort of polarization is stable: no amount of evidence from the scientists who have adopted the correct belief will be enough to convince those who adopted the wrong belief. And the polarization does not depend on individuals not seeing the evidence of those with different beliefs. They receive this evidence just as before. They simply do not believe it. — Cailin O’Connor and James Owen Weatherall, The Misinformation Age, 249

Categorization

• DEEPTHINKING: The demonstration that simply weighting evidence by trust in its source — with no irrationality, no bias, no hidden motives — yields stable polarization insensitive to counter-evidence is a paradigm-shifting result about how distrust alone can foreclose consensus.
• XREF: Directly models the chronic Lyme and climate-change polarization cases this chapter describes, and extends the earlier themes of rational agents forming collectively irrational outcomes. — connects to: False beliefs mostly persist through social transmission, not individual failings — Cailin O’Connor and James Owen Weatherall, The Misinformation Age: How False…, 30; Polarization similarity hides distinct causes requiring opposite interventions — Cailin O’Connor and James Owen Weatherall, The Misinformation Age: How False…, 311; Polarized groups bundle unrelated beliefs into correlated packages — Cailin O’Connor and James Owen Weatherall, The Misinformation Age: How False…, 464 (+2 more)
• recurring: this claim recurs 2 times within its source