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Unsharp Sharpness



In a recent, thought-provoking paper Adam Elga ((2010) argues against unsharp – e.g., indeterminate, fuzzy and unreliable – probabilities. Rationality demands sharpness, he contends, and this means that decision theories like Levi's (1980, 1988), Gärdenfors and Sahlin's (1982), and Kyburg's (1983), though they employ different decision rules, face a common, and serious, problem. This article defends the rule to maximize minimum expected utility against Elga's objection.