Fat-Tailed Distributions, Applied Volcanology, and Decision Support—A Perspective

Roger Cooke demonstrates that, under fat-tailed uncertainty, aggregation of expert point forecasts can fail dramatically, challenging the validity of the wisdom-of-crowds approach. In certain circumstances—for example, in extreme natural hazards—disregarding fat-tailed risk distributions can create an acute danger to public safety. This commentary reflects on Cooke’s findings from the perspective of applied volcanology and decision support in high-stakes situations. Empirical evidence from structured expert judgment panels indicates that forecast uncertainties often exhibit extreme tail behavior, undermining the assumptions that justify averaging. In such settings, aggregation of full probability distributions—particularly when performance-weighted—offers a more robust framework. Drawing on experiences from volcanic crisis management and contrasting these with shortcomings observed in the UK COVID-19 response, this paper argues that effective decision analysis requires formal quantification of uncertainty, multidisciplinary integration, and mathematically coherent aggregation methods.