Edward H. Levi

Although ancient and medieval theorists of law took it for granted, as we have seen, that human law cannot produce certainty, only recently has the relationship between the logic of the law and its capacity to combine stability with change and uncertainty been spelled out. In the classic modern work on the subject, An Introduction to Legal Reasoning (1948), Edward Levi says bluntly that the law operates under a pretense: “The pretence is that the law is a system of known rules applied by a judge.” He goes on to explain that it is a pretense because no rule of law can absolutely specify a decision. This gap between general rules and particular decisions means that rules of law are always ambiguous. The ambiguity is inescapable because of the logical relationship between any general proposition and a more particular one. Any given particular can be fitted into a variety of general statements, and the particulars that could be implied by a general statement cannot be exhaustively stated. Thus, the character of the logical relationship between a general rule and a particular instance makes it impossible for any general rule, however clear, to yield only one correct decision.

Only with general statements of a perfectly abstract nature, as with figures the sum of whose angles is 180 degrees, can the particulars fitting under it be unambiguously identified. In the law, the rules are general but not abstract.