Cohesion as Concentration: Exclusion-Driven Fragility in Financial Organizations

Financial crises repeatedly reveal organizations that appear internally aligned while failing to recognize accumulating tail risks. This paper argues that cohesion is observationally ambiguous. It can arise from information integration, in which heterogeneous inputs are debated and synthesized, or from exclusion, in which variance is removed through conformity pressure, gatekeeping, and intolerance of dissent. This distinction is formalized using a signal aggregation model in which an organization maintains an anchor belief and achieves agreement through two exclusion channels: report shrinkage toward the anchor and a tolerance rule that discards reports deviating beyond a threshold. Relative to a full inclusion benchmark, exclusion based cohesion jointly produces state contingent bias that is small in normal regimes but grows sharply under displacement, illusory precision in which observed disagreement falls as tail regime estimation error rises, effective concentration of decision inputs below the nominal participant count, and, when the anchor updates from filtered aggregates, dynamic lock in with delayed regime recognition and abrupt correction. External inputs that bypass internal filtering shorten recognition delays. The model yields testable governance diagnostics linking latent fragility to observable patterns in recorded dissent, anonymous to formal voting gaps, scenario set diversity, pipeline and method concentration, and anchor lag. The central implication is that governance systems should treat low internal conflict and unanimity as potentially diagnostic of variance depletion and should monitor whether heterogeneity is integrated or excluded before stress reveals the difference.