Logos: inductive reasoning
Pathos: the appeal to emotion

Logos: argument by analogy

Have you ever argued that the facts of your case resemble those in a reported decision, so that whatever ruling was made in the reported decision should also be made in your case? On the flip side, have you ever argued that a ruling in a reported case should not be made in your case because of a crucial difference between the facts in the reported case and the facts in your case? The answer to both questions is probably “yes.” As 1L’s, we all learned to analogize friendly cases and distinguish unfriendly cases. In rhetorical terms, we learned to argue by analogy.

In classical rhetoric, argument by analogy comes under the heading logos, or appeal to reason and logic. As explained by Edward Corbett and Robert Connors, the argument by analogy “revolves around the principle that two things which resemble one another in a number of respects resemble one another in a further, unconfirmable respect.” Corbett and Connors further explain that the persuasiveness of an argument by analogy depends on two principles:

  1. The similarities between the two things concern pertinent, significant aspects of the two things.
  2. The analogy must not ignore pertinent dissimilarities between the two things.

For legal argument, the strength of the analogy also depends on a third principle: binding cases are more important than merely persuasive cases.

When we seek to distinguish unfriendly cases, the principles work in reverse—especially the second one. Any dissimilarities we point out must be pertinent; otherwise the court may consider the argument a “distinction without a difference.” And if the reported decision is non-binding, it never hurts to point that out.

A way to think about analogy is to compare it to deductive reasoning and inductive reasoning. Deductive reasoning moves from the general to the particular. Inductive reasoning moves from the particular to the general. Analogy moves from the particulars of one case to the particulars of another, showing either their similarities or dissimilarities.

Here are the sources for this post and recommendations for further reading:

  • Edward P.J. Corbett and Robert J. Connors, Classical Rhetoric for the Modern Student 69, 93–95, and 119 (4th ed. 1999).
  • Ruggero J. Aldisert, Logic for Lawyers 51–52 and 93 (3d ed. 1997).


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