There is good reason to remain skeptical of overly rationalistic accounts of law and judicial practice. The weave of historical doctrine, legal principle, and factual nuances that goes into each judicial decision is far too intricate to permit critical appraisal under any single evaluative method, including the principles of logic. So we are rightfully apprehensive when we recollect the formalistic visions of nineteenth century jurists — visions which found the essence of adjudication in the logical derivation of conclusions necessarily required by predetermined legal principles.
Yet it is somewhere between strict formalistic jurisprudence and an outright disregard for logic and argumentative form where the law and judicial practice really find repose. Though all that is typically repeated of Justice Holmes’ view is the pithy remark quoted above, his jurisprudential writings together with his judicial opinions show clearly that he never intended to suggest that logic is not a central aspect of law or judicial decision making. He, as well as the legal realists and other critics of legal formalism, well recognized that evaluating and creating arguments lie at the heart of the crafts of lawyering and judging.
It is thus worthwhile for practitioners and students of the law alike to possess an understanding of the basic principles of logic that are used regularly in legal reasoning and judicial decision making. This understanding requires, in important part, skill in navigating the processes of inductive reasoning — the methods of analogy and inductive generalization — by which inferences are drawn on the basis of past experience and empirical observation. The common law method of case law development, as well as the general prescript often referred to as “the Rule of Law” — that like cases be decided alike — are grounded logically in inductive reasoning.
Equally important is a second basic category of argumentation — deductive logic, especially the deductive argument forms known as “syllogisms.” These are the classic forms of deductive argument consisting of a major premise, a minor premise, and a conclusion. It was this aspect of logic that a century ago stirred such virulent opposition to formalism. And it is this aspect of logic which was so severely downplayed throughout the twentieth century. Yet even a rudimentary understanding of deductive logic gives lawyers, judges, and students of the law a valuable tool for determining whether an argument in a legal opinion or brief is valid or fallacious.
In essence, the domain of the law and, within that domain, perhaps most especially the practice of judicial decision making are exercises in practical reasoning. Law, to be sure, involves more than logic. Yet the myriad of factors that contribute to good lawyering and fair judging suggest that the “life of the law,” while not logic alone, is a manifold of activities that all use and depend upon reason in specialized ways. The precision of detail required in the drafting of contracts, wills, trusts, and other legal documents is a rational precision; the care in planning and strategizing demanded of trial attorneys in deciding how to present their cases is a rational care; the skill in written and oral argumentation required for appellate practice is, quite obviously, a rational skill; the talent expected of administrative law judges in crafting coherent findings of fact and conclusions of law is a rational talent; and the ability of trial and appellate court judges to separate, dispassionately and without bias, the kernel of argument from the rhetorical and emotive chaff of adversarial presentation, so as to render judgments that are justified under the law, is a rational ability.