Traditional legal perspectives on analogical reasoning in law posit that legal reasoning involves the initial step of recognizing a similarity between the facts of some previous case and the facts of the instant case. And the recently widespread skeptical views see the claims of analogical reasoning in law as little more than a mask for unacknowledged judicial lawmaking. Against both of these views, we argue that analogical reasoning, in law and elsewhere, involves an initial perception of similarity, but a perception that is based on the knowledge, experience, training, and possibly the expertise of the person drawing the analogy. As a result, analogical reasoning in law differs from simple rulemaking or lawmaking, but does embody the categories embedded in the distinctively legal knowledge and experience that lawyers and judges bring to bear on the process of analogical reasoning.


Analogy is central to legal reasoning, legal argument, and legal justification. Or so it is said. For many judges, scholars, and commentators, analogical reasoning lies at the core of the common-law process. Indeed, many of those same judges, scholars, and commentators believe that analogical reasoning is at the heart not only of common-law decision-making, but also of the very idea of distinctively legal reasoning. Yet for other judges, scholars, and commentators, the traditional celebration of analogical reasoning in law rests on shaky foundations, often (or inevitably) serving to mask the lawmaking dimensions of legal argument and legal decision-making. For this latter group, the traditional celebration of analogical reasoning is at best misguided, and at worst pernicious.

One goal of this Essay is to describe these debates about analogical reasoning in law, debates that include some number of variations on the major themes of celebration of, or skepticism about, the role of analogy in legal argument. But it turns out that both the celebratory and the skeptical positions are partly correct and significantly incorrect. The skeptics are correct in believing that drawing analogies requires the intermediation of the principles (or rules, in a broad sense1) that are essential for the determination of similarity and difference. But the celebrants are just as correct in insisting that legal decision-makers might often not consciously perceive such principles, and thus that decision-
makers understand themselves to be moving from particular to particular without the conscious intervention of principles guiding them in the determination of what is analogous to what.

Once we see that determining why one thing seems similar or analogous to another often occurs without conscious deliberation, we can begin to glimpse the role that the experiences of the analogizer play in drawing analogies and in distinguishing good analogies from poor ones. And because lawyers and judges have training and experience that diverge from the training and experience of others, analogical reasoning in law turns out to be different from analogical reasoning in everyday life. But this is not because lawyers and judges have some special facility in analogical reasoning. We believe that the existing body of psychological research strongly supports the conclusion that there are no experts in analogical reasoning.2 But there are experts in law, and it is this legal expertise that plays a major role in the use of analogical reasoning in legal settings. As a result, analogical reasoning in law may differ from analogical reasoning in everyday life not because the fundamental process of analogizing is different in law from what it is in nonlegal settings, but because the informational and experiential background that is essential for drawing an analogy in the first place serves to distinguish legal analogizing from lay analogizing. Or so we argue here.

Not surprisingly, the techniques that lawyers use in making legal arguments and judges use in making and justifying legal decisions resurface in the context of external commentary on, and evaluation of, legal decisions or lines of legal doctrine.3 In keeping with the theme of some of the contributions to this Symposium, therefore, we note that analogical argument is widespread in legal scholarship, as scholars use analogies to evaluate legal outcomes. Analogical reasoning can thus be understood as an existing approach to legal scholarship, and our conclusions about the nature of analogical reasoning in law should be understood to apply, mutatis mutandis, to analogical reasoning about law.

  • 1. Unless otherwise noted, we use the terms “rules” and “principles,” and sometimes “theories,” interchangeably. At least for purposes of this Essay, all refer to overarching generalizations that make it possible to group otherwise-heterogeneous acts, events, or objects under the same heading.
  • 2. See Barbara A. Spellman, Judges, Expertise, and Analogy, in David Klein and Gregory Mitchell, eds, The Psychology of Judicial Decision Making 149, 162 (Oxford 2010); Barbara A. Spellman and Frederick Schauer, Legal Reasoning, in Keith J. Holyoak and Robert G. Morrison, eds, The Oxford Handbook of Thinking and Reasoning 719, 731 (Oxford 2012).
  • 3. It need not be so, and perhaps it would be good if it were somewhat less so. Although much of academic commentary on legal doctrine uses the techniques of legal reasoning, including but not limited to the use of analogies, to criticize (and, rarely, to endorse) legal doctrine and judicial decisions, there is no reason to believe that external commentary on decisions must mimic the methods used to make those decisions. Still, the use of analogical reasoning in legal scholarship is ubiquitous, and thus much that we say about analogical reasoning in law applies to the use of such reasoning in scholarship about the law as well.