In modern evidence theory two main theories of legal factfinding have emerged. One of these is the mathematical probabilistic approach, which claims that the universal rules of mathematics apply to legal factfinding as to any other rational decision-making. The opposite approach, of Tribe, Nesson and others, contests this view. Those opposing the mathematical theory have done so mostly on grounds of legal policy, which I shall not be concerned with. However, some of the sharpest criticism, at least from the point of view of the adherents of the mathematical explanation, has been of the soundness of the mathematical explanation. In certain instances typical to the legal process, the mathematical approach has been claimed to lead to absurd results which contradict common sense and legal doctrine.In this paper I will claim that the rules of mathematical probability must apply to legal factfinding and if fallacies in its application are exposed, their existence must be due to error in the way in which the rules have been applied. I will argue and try to prove that the concept of relevance, an essential concept to any theory of legal factfinding, has been disregarded in mathematical probability theory.