The word epicheirema comes from the Greek “epicheirein, to endeavor, attempt to prove” (Webster, epicheirema). It translates into Latin as ratiocinatio (Cicero), “reasoning”, or as argumentatio (Ad. Her.)

The term epicheirema is used in ancient argumentation theory with three distinct definitions.

1. Epicheirema as dialectical reasoning

The Aristotelian theory of syllogistic reasoning opposes philosopheme to epicheirema. Philosopheme is another name for the analytical or scientific syllogism, where the premises are true and the rule of deduction is valid (Top., VIII, 11; p. 156). In contrast “epicheirema is a dialectical inference” (ibid.), that is, a syllogism founded on premises taken from the doxa, hence only probable; this inference concludes to a probability.

2. Epicheirema as an argumentation
whose premises are themselves argued

In rhetorical argumentation, the word epicheirema is a synonym of probable (rhetorical) syllogism, enthymeme and argumentation. A well-built, convincing, rhetorical proof is defined as an argumentation (ratiocinatio) whose premises are only probable, and, consequently, should be explicitly backed by their proofs (Cicero, Inv. I, 34; Hubbell, p. 98-99). In short, a probable premise accompanied by its proof becomes certain. Cicero discusses the following rhetorical syllogism (id., 101-103)

— Premise 1 + Proof of Premise 1:

Premise 1: “Things that are governed by design are managed better than those that are governed without design”
Proof of Premise 1: “The house that is managed in accordance with a reasoned plan is better managed that those that are governed without design. The army […] The ship […]”

— Premise 2 + Proof of Premise 2:

Premise 2: “Of all things, nothing is better governed than the universe”
Proof of Premise 2 (our numbering and presentation)
(a) “the rising and the setting of the constellations keep a fixed order”
(b) “and the changes of the seasons not only (b1) proceed in the same way by a fixed law but (b2) are also adapted to the advantage of all nature,
(c) “and the alternation of night and day has never through any variation done any harm.”

— Conclusion: “Therefore, the universe is governed by design.”

Premise 1 is the conclusion of an induction, that is an enumeration of examples, sharing the same structure and orientation. In premise 2, case (b), the element (b2) argues not only for a design but also for a benevolent design, as does case (c).

Structure of an epicheirema

The question as to whether an epicheirema includes five or three components is disputed (Solmsen 1941, p. 170). On the surface level, an epicheirema is indeed a sequence consisting of five components:

Premise 1 + Proof of Premise 1 + Premise 2 + Proof of Premise 2 + Conclusion

This corresponds to a three-element deep structure:

(Premise 1 and its Proof) — (Premise 2 and its Proof) — Conclusion

This is Quintilian’s position: “To me, as well as to the greater number of authors, there appears to be not more than three [parts]” (IO, V, 14, 6).

The epicheirema corresponds to a linked argumentation, represented as follows:

3. Epicheirema, as a communicated argument

The Rhetoric to Herennius defines “the most complete and perfect argument [argumentatio]” as “that which consists of five parts: the Proposition, the Reason, the Proof of the Reason, the Embellishment and the Résumé” (Ad Her., II, 28).

This perfect rhetorical argument is described as a sequence consisting of five components, like a logical epicheirema, but with a quite different organization. The first three elements correspond to the logical component, establishing the Proposition:

Reason 1 + Proof of the Reason + Proposition

The proof of the Reason, “corroborates by means of additional arguments, the briefly presented Reason” (Id., p. 107). The argumentation must now be seen as serial:

[Argument1   =>       {(Conclusion] = Argument2)    =>  Conclusion}
Proof of the Reason                    Reason                                Claim

The Embellishment is a reformulation that “adorn[s] and enrich[s] the argument (argumentatio)”. The Résumé is not the conclusion; its “[brevity]” contrasts with the preceding amplification episode, creating a kind of hot / cold contrast. This second component of the argumentation articulates two elements that clearly have a communicative function.