Where are statistics and principled probabilistic thinking in law and legal education? Many law students shudder at the thought of any sort of computational mathematics or mathematical reasoning, and I have often heard my fellow students repeat the old joking excuse when anything numbers-related comes up in class: “I went to law school so I wouldn’t have to do math anymore,” or “I went to law school, because I can’t do numbers.” While perhaps understandable (law school is hard enough as it is without learning some math, and traditionally, statistics and probability are not what you think you are getting into when you take the LSAT), this type of sentiment is obviously analytically wasteful. Probabilistic and statistical understandings are tools that can help lawyers better comprehend the law, reach optimal solutions to legal problems, and combat pervasive cognitive bias.

The legal field has made some steps toward fostering statistical and probabilistic literacy, but these analytical tools still remain marginalized. They are relegated to specific aspects of criminal law and tort. In the course of a normal legal education, the law student can probably get by unscathed or at worst with introduction to People v. Collins, the classic example of good and bad statistical reasoning in the criminal law arena (and for a little more about the guy who did the good reasoning, see here). A law student will probably also be exposed to some sort of demonstration of how numbers can provide an analytical framework for determining some artificially optimal social behavior in tort (i.e. “the standard of care”), as well.

Despite this limited exposure and application of statistical and probabilistic analysis, the usefulness of these analytical tools is much more broadly applicable to the law in general. Common cognitive biases occur in legal reasoning that can be combated with a general understanding of probabilistic and statistical analytical methods. Several classic examples immediately inform on the value of such analysis. Consider the Monty Hall Problem, which makes conspicuous our tendency to botch our determination of probabilities and the role of independence in analysis. Additionally, formal analysis of probabilities through the theory of Bayesian updating (for an introduction, see here; for a more rigorous explanation, see here), which is a nebulous and abstract process without quantification, can make abundantly clear the insidious problems that often come with attempting to assign probabilities to real events.

To conclude, many types of lawyers do not need to understand the nature of basic probability and statistics, but understanding these things can help lawyers optimize their solutions to legal problems and bring real help to real people. To defeat the tyranny of numbers, which I believe actually lies with our fear of and incompetency with numbers, not in the numbers themselves, I appeal to you that we must be brave and learn to be comfortable and competent with them.

Dan Ward


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