What can increase
Similarity among beliefs
Participants' estimates, models, or conclusions move closer together.
A dissociation
More similar beliefs ≠ better collective judgment
A group can become more internally aligned while becoming less accurate.
Epistemic convergence can feel like progress. Disagreement falls, confidence rises, and the group becomes easier to describe as sharing a view. But some collective judgments depend on preserving partially independent information and error.
≠
What can decrease
Collective accuracy
The aggregate judgment can lose information when previously independent errors become correlated.
A revealing result
Social influence can reduce the wisdom of crowds.
When people are exposed to one another's estimates, their judgments can converge and their confidence can increase.
But convergence can also reduce the diversity that allowed individual errors to cancel out in the aggregate.
What this reveals
The relevant alignment target may live at another scale.
If we measure alignment among individuals, increasing similarity looks like improvement.
If we measure the accuracy of the collective, preserving some independence can be more important than agreement.
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