Discussion paper: The structure and the logic of proof in trials

Abstract

If one travels across time, continents and cultures, one needs to attend to the interests and attitudes of one’s audience. If one does not do so, one risks being thought strange. Of course, the same may hold true if one travels just from New York City to Texas (a mere 1600 miles or so). Many years ago I traveled from New York City, where I was teaching at the time, to Houston, Texas, to give a talk at one of the law schools in Houston. At the time I was much preoccupied with the work that had been done by people in artificial intelligence. I was interested in such stuff because I wondered about the possible applications of that research to the study of evidentiary processes in litigation and adjudication. In my talk in Houston, I tried to explain my tentative conclusion that artificial reasoning methods (including statistical methods) could not supplant ordinary methods of reasoning. After the talk, it soon became apparent that some or much of the audience viewed me as closely akin a man from Mars.1 In this paper, I will use some words—words such as ‘ontology’—that may seem strange or repellent to some or many readers. So I thought I would begin by talking briefly about some of my motivations for talking in ways that may seem strange or unpleasant to some or many readers. Several decades ago I revised the first volume of John Henry Wigmore’s multivolume treatise on the law of evidence.2 Being a reviser is both harder and easier than being an author of one’s own book. It is easier because one can, if one wishes, take the position of a critic and commentator rather than that of author. And in dealing with some or many of the theoretical portions of Wigmore’s magnum opus, I often did exactly that. However, after finishing my revision, I agreed to write a successor to my revision. Now, after a delay of many years, I am doing that. The job of this successor volume, like part of its precursor, is to examine ‘theoretical considerations’ that bear on the law of evidence and proof. This means that I can no longer just be a commentator. Now I must present my own ‘theory of proof’. In looking at what others had done in trying to develop a theory of the law of evidence and proof, I saw many impressive accomplishments. I also saw a variety of approaches. On the one hand, some of the authors seemed to focus on the abstract logic of uncertain reasoning; and their theory of the law of evidence and proof (a theory that they often called a theory of ‘relevance’) effectively amounted to their view of the nature of logical thinking about uncertain factual propositions.3 It seemed to me then—and it seems to me now—that there is something wrong with this approach. Above all, I wondered and I wonder still how it can be confidently said that the methods of reasoning and demonstration in a particular legal system (such as the American one) rest on and express such logic.