The argument from the precedent corresponds to the topic n° 11 of Aristotle’s Rhetoric:

Another line of argument is founded upon some decision already pronounced, whether on the same subject or on one like it or contrary to it. (Rhet., II, 23, 11; RR, p. 365)

“Judgment” not only refers to the sentence of a court but to any assessment or decision taken in the past, in ordinary life as well as in the political sphere or in the legal domain. And if the cause has not been settled in a formal assembly, it may have been by such authorities as known fables, parables or examples, proverbs or celebrated verses (Lausberg [1960], § 426).

Judgments are made in the context of past judgments concerning cases “of the same type”, that is belonging to the same legal category, S. Categorization. The importance granted to the precedent is a requirement of continuity and consistency between decisions made in the past and the decision to make, a particular application of the non-contradiction principle. The structural coherence of the involved discursive field is thus strengthened, and guarded against any ad hominem charge addressed to the institution, S. Ad hominem.

In much the same way as the argument ab exemplo, the argument from precedent motivates a decision or interpretation by relying upon data or examples drawn from tradition. It is a conservative principle, which limits innovation in all domains in which it applies. As such, it combines well with arguments appealing to “the wisdom of our ancestors” (Bentham, 1824; S. Political argument; Authority; Progress.

The precedent principle progresses in the following stages:

(i) A problem, P1, a case about which a decision has to be made.
(ii) Research of similar problems and cases, resulting in
(iii) A categorization: this case is similar to a prior case P0; it falls within the same category as P0, S. Analogy (II); Categorization.
(iv) The decision, judgment, evaluation … E was made about P0;

(v) By application of the rule of justice, a similar judgment has to be made about P1. “Similar” means here the same judgment, a judgment proportional, or opposite; or, more simply, a judgment consistent with E.

The invocation of the precedent can be blocked at the second stage, where it can be argued that there are essential differences between P1 and the previous case P0.

The appeal to the precedent saves time and energy. The problem of judgment is automatically solved as soon as analogy is drawn between the problematic fact and an established fact.