The notion that a false positive (false conviction) is worse than a false negative (false acquittal) is a deep-seated commitment in the theory of criminal law. Its most illustrious formulation, the so-called Blackstone’s ratio, affirms that “it is better that ten guilty persons escape than that one innocent suffer”. Are people’s evaluations of criminal statutes consitent with this tenet of the Western legal tradition? To answer this question, we conducted three experiments (total N = 2492) investigating how people reason about a particular class of offenses—proxy crimes—known to vary in their specificity and sensitivity in predicting actual crime. By manipulating the extent to which proxy crimes convict the innocent and acquit those guilty of a target offense, we uncovered evidence that attitudes toward proxy criminalization depend primarily on its propensity toward false positives, with false negatives exerting a substantially weaker effect. This tendency arose across multiple experimental conditions—whether we matched the rates of false positives and false negatives or their frequencies, whether information was presented visually or numerically, and whether decisions were made under time pressure or after a forced delay—and was unrelated to participants’ probability literacy or their professed views on the purpose of criminal punishment. Despite the observed inattentiveness to false negatives, when asked to justify their decisions, participants retrospectively supported their judgments by highlighting the proxy crime’s efficacy (or inefficacy) in combating crime. These results reveal a striking inconsistency: people favor criminal policies that protect the rights of the innocent, but report comparable concern for their expediency in fighting crime.

假阳性（误判）比假阴性（假无罪）更糟糕的观念是刑法理论中根深蒂固的承诺。它最著名的公式，即所谓的黑石比率，断言“十个有罪的人逃脱比一个无辜的人受苦要好”。人们对刑法的评价是否符合西方法律传统的这一宗旨？为了回答这个问题，我们进行了三个实验（共N = 2492) 调查人们如何推理特定类别的犯罪——代理犯罪——已知在预测实际犯罪时其特异性和敏感性各不相同。通过操纵代理犯罪对无辜者定罪和使目标犯罪者无罪的程度，我们发现了证据表明对代理犯罪的态度主要取决于其对误报的倾向，而漏报的影响要弱得多。这种趋势出现在多个实验条件下——无论我们是否匹配假阳性和假阴性的比率或它们的频率，无论信息是以视觉还是数字方式呈现，以及决定是在时间压力下还是在被迫拖延之后做出的——与参与者的概率素养或他们对刑事处罚目的的公开观点无关。尽管观察到对假阴性的疏忽，但当被要求证明他们的决定是合理的时，参与者通过强调代理犯罪在打击犯罪方面的功效（或无效）来回顾性地支持他们的判断。这些结果揭示了一个明显的不一致：人们赞成保护无辜者权利的刑事政策，但也报告了他们对打击犯罪的权宜之计的类似关注。