Hugo Mercier and Dan Sperber · 2017

The Enigma of Reason

A New Theory of Human Understanding

Rough AI truth score

67/100

The book offers a powerful reframing: explicit reasoning often functions socially, helping people produce and evaluate justifications, and structured disagreement can improve answers. The evidence supports a major argumentative function but not a uniquely primary evolutionary function. Group reasoning succeeds only with diversity, genuine disagreement, shared standards, and access to relevant evidence.

Based on three central claims · medium confidence

The three claims

01Mostly supported

Human reasoning often serves the production and evaluation of arguments in social settings.

Developmental, experimental, and discourse evidence shows early argument skills, selective evaluation of reasons, and systematic production-evaluation asymmetries. Reasoning also supports planning, causal inference, mathematical proof, counterfactual simulation, and individual problem solving, so its functions are not exhausted by argumentation.

Why Do Humans Reason? Reasoning Serves Argumentation in Children

02Mostly supported

Diverse groups can outperform isolated reasoners when claims are genuinely contested and evidence is shared.

Independent error, criticism, and pooling can allow groups to find and retain correct arguments that individuals miss. Benefits disappear or reverse with correlated information, conformity, status pressure, polarization, hidden profiles, weak incentives, or no mechanism for identifying the better argument.

Argumentation and Evolution of Reasoning Argumentation Evolved: But How?

03Mixed

Argumentation is the primary evolved function explaining confirmation bias and most characteristic reasoning failures.

The theory parsimoniously explains why people generate support for their own views yet can evaluate others' arguments more critically. Evolutionary primacy is difficult to test, confirmation bias has multiple forms and functions, and comparative, developmental, and computational alternatives remain viable.

The Enigma of Reason Reasoning, Logic, and Development Review

Other claims worth checking

Myside search can be locally efficient within well-designed adversarial institutions.
Reason evaluation and reason production need not have symmetric accuracy.

What this number means. It is an AI-generated first-pass judgment of three central factual or causal claims—not a rating, exhaustive fact-check, or human peer review. Claim credits are 100% for supported, 75% for mostly supported, 50% for mixed, and 25% for weak, then averaged and rounded. Lower confidence means the score should move more as better evidence arrives.

Method three-central-claims/0.1.0 · checked 2026-09-01 · 3/3 selected claims assessed · method and source audit