If a plaintiff brings two claims, each with a 0.4 probability of being valid, the plaintiff will usually lose, even if the claims are based on independent events, and thus the probability of at least one of the claims being valid is 0.64. If a plaintiff brings two independent claims, and neither of them alleges misconduct sufficient to justify a remedy, the plaintiff will usually lose, even if the claims jointly allege sufficient wrongdoing to justify a remedy. Thus, as a general rule, courts refuse to engage in what we call factual aggregation (the first case) and normative aggregation (the second case), as well as other forms of aggregation that we identify. Yet we show numerous exceptions to this rule in private and public law. Notably, ...