ENTHYMEME

1. The Greek Word

The Greek word corresponding to the English words enthymeme (and the adjective enthymematic) means (Bailly, [enthymema]):

1. 1. Thought, reflection.
   2. Invention, especially a war stratagem.
   3. Reasoning, advice or warning.
   4. A reason, a motive.

The general meaning of “thought, reflection” is present in all ancient rhetoric: “Every expression of thought is properly called an enthymeme. » (Cicero, Top., XIII, 55; p. 423A
Quintilian also alludes to the meaning “everything that is conceived in the mind”, to set it aside (IO, V, 10, 1).

2. An Instance of a Topos (Argument Scheme)

In rhetorical argumentation, an enthymeme is essentially an instance of a topos. An argument scheme is a general formula having an inferential (associative) form. An enthymeme is the application of such a formula to a specific case.
This general definition is combined with the following orientations:

(i) In relation to logic, the enthymeme is:

— A form of syllogism:

• • • • • • A syllogism based on a plausibility or a sign.
          • A truncated syllogism.

— The counterpart of the syllogism.

(iii) Functionally, the enthymeme is a manifestation of cooperation with the audience.

(iv) Additionally, the enthymeme has also been defined as a concluding formula.

3. A Special Kind of Syllogism

3.1 The Enthymeme is a Syllogism Based on “a Probability” or “a Sign”

In the Prior Analytics, Aristotle defines the enthymeme as “a syllogism starting from probabilities or signs” (P. A., II, 27).

A natural sign is a proposition that expresses a natural connection between two states of affairs. The connection may be probable (to be red is a sign or a symptom of fever) or necessary (smoke is a sign of fire).

An enthymeme is a probable reasoning such as:

Peter is tired, he must have worked hard.

Depending on the range of context considered by the analyst, the arguer may be accused of mistaking necessary and sufficient conditions, or he may be trusted to know for certain that Peter did not spend the whole night partying.

A probability is a proposition thar expresses either a probable natural relation or a social agreement.

A probability is a generally approved proposition: what people know will or won’t happen, will or won’t be, is a probability, e.g. “the envious hate”, “the beloved show affection”. (Aristotle, PA, II, 27)

These are excellent examples of associative semantic inferences (+ envious, + hate); (+ love, + show love), see orientation; topos in semantic. Such substantial probabilities are based on common-sense views of basic human tendencies. The corresponding topics underlie the current production of arguments; see common place.
For example, the big strong man will prevail over the small weak one, and mothers love their children. Sometimes, however, this is not the case. A characteristic of reasoning from social probabilities is that it can be reversed, as expressed in the key Aristotelian topic #21, “incredible things do happen” (Rhet, 2.22, 1400a5; RR p. 373).

Consistency is generally a source of probability. People are rational, intentional beings; they make plans and are expected to act according to those plans, and remain true to their words and intentions. Their behavior is presumed to be probably consistent. Inconsistency is the sign of a defective personality, or of a basic mistake, see consistency; ad hominem. Demonstrating that an opponent is incoherent is a key strategy for rejecting claims or narratives.
However, as noted in topos #21, consistency is only a probability, and probabilities cannot hold up against hard evidence; they are only default, everyday qualifications.
Other topoi are based on inconsistent behavior: People change their minds and criminal actions may be poorly planned, see motives.

3.2 The Enthymeme is a Truncated Syllogism

The enthymeme is also defined as a categorical syllogism in which a premise is omitted:

Men are fallible, you are fallible.
You are a man, you are fallible.

Or the conclusion:

Human are fallible, after all you are a human!

The Logic of Port-Royal defines the enthymeme as:

A syllogism that is perfect in the mind, but imperfect in the expression, because one of the propositions is suppressed as too clear and too well known, and as being easily supplied by the minds of those to whom we speak. (Arnauld, Nicole, [1662], p. 224).

No enthymeme is conclusive, except in virtue of an understood proposition, which, consequently, has to be in the mind though it be not expressed. (Id., p. 207).

The example in the preceding paragraph can therefore be called an enthymeme for two reasons: First, it is based on probable indices; second, it is an incomplete syllogism.

However, the definition of an enthymeme as a truncated syllogism is often not considered to be Aristotelian: “It is not of the essence of the enthymeme to be incomplete.” (Tricot’s Note to Aristotle, PA, II, 27, 10, p. 323).
Furthermore, according to Conley, this conception of the enthymeme as a truncated syllogism was not widely used in ancient rhetoric. Conley only finds it in one passage in Quintilian (Conley 1984, p.174).

The First Analytics does consider the case of the truncated syllogism, “Men do not say the latter [Pittacus is wise] because they know it” (PA, II, 27, 10). On the other hand, we read in the Rhetoric that:

If any of these propositions is a familiar fact, there is no need even to mention it; the hearer adds it himself. Thus, to show that Dorieus has won a contest for which the prize is a crown, it is enough to say ‘For he has won the Olympic games,’ without adding ‘And in the Olympic games the prize is a crown’, a fact that everyone knows. (Rhet., I, 2, 1357a15; RR, p. 113).

According to this definition, the enthymeme can be considered as a figure of speech by ellipsis, precisely a figure of thought.

4. The Rhetorical Counterpart of the Syllogism

In the Aristotelian system, the proof is obtained by inference, whether it is scientific (logical), dialectical, or rhetorical. For Aristotle, there are two types of scientific inference, syllogistic deduction and induction. In rhetoric, scientific inference is replaced by “rhetorical inference” or enthymeme, since the requirements of rhetorical discourse are incompatible with the exercise of scientific inference:

I call the enthymeme a rhetorical syllogism, and the example the rhetorical induction. (Rhet., I, 2, 1356b5, RR, p. 109)

The syllogism (scientific inference) and the enthymeme (rhetorical inference) are defined in a strictly parallel way:

When it is shown that certain propositions are true, and in consequence, a further and quite distinct proposition must also be true either invariably or usually, this is called a syllogism in dialectic, and an enthymeme in rhetoric. (Rhet., I, 2, 1356b15; RR, p. 109)

Unlike the syllogism, which is derived from true propositions, the enthymeme is drawn from “probabilities and signs” (Rhet., I, 2, 1357a30; RR, p. 113), see supra § 3.1.

The enthymeme is “the substance of persuasion”, “a sort of demonstration” (Rhet., I, 1, 1354a10, RR p. 95; 1355a5, RR p. 99). It deals centrally with the issue at hand, the substance of the debate, “the fact” (Rhet, I, 1, 1354a25, RR p. 97. As such, the enthymeme is opposed to the reckless use of ethos and pathos, see emotion.

The enthymeme is also called a rhetorical syllogism, and is considered as an imperfect syllogism. These labels refer to rhetoric as syllogistic. However, the scientific / dialectical / rhetorical parallelism, attractive as it may be, is problematic. To accept this opposition, is to enter an uncomfortable and empirically inadequate conceptual grid.
— On the one hand, the distinction between the three types of reasoning creates a divide between the categorical scientific syllogism and the probable dialectic syllogism, versus the persuasive rhetorical enthymeme. This distinction implies that socially relevant discourse is inherently incapable of addressing with well-founded truth.
— On the other hand, argumentative rhetoric is straitjacketed by the opposition between technical evidence, proper rhetorical evidence, and nontechnical proof, which do not fit into the previous notional framework. Common legal discourse routinely combines the two types of proof, in perfectly syllogistic forms of reasoning, see layout; demonstration.

The reasons given for tying the enthymeme to syllogistic discourse are somewhat paradoxical. The enthymeme as a truncated syllogism is said to suit rhetoric because it is less pedantic than the complete syllogism. This assumes that the missing premise is easily retrievable. Another reason given is that one would use an enthymeme because the average audience has mediocre intelligence, and cannot follow a rigorous syllogistic chain. However, this second justification assumes that the missing premise is too difficult to recover. These two justifications are not immediately compatible.

5. Enthymeme and interpretative cooperation

From the perspective of argumentative communication, the enthymeme uses implicit information to achieve persuasion (Rhet., I, 2, 1356b5, RR p. 109).
As Bitzer notes (1959, p. 408), the enthymematic form connects the speaker and the audience in the co-construction of discourse meaning, “the enthymeme is satisfied if merely what is stated in it is merely understood”, (Quintilian, IO, V, 14, 24). By constructing a common speech space, implicitness produces intersubjectivity. The speaker frames the audience as good listeners, and creates an atmosphere of complicity and “good intelligence”. This communicative fusion thus contributes to the formation of an ethos: “You understand me. You can read my mind. I am like you. We are together.”

In Jakobson’s terms, the enthymematic formulation of reasoning has a phatic function, that is, it maintains an open communication channel. The surprise effect associated with the ellipsis is intended to awaken a sleepy audience: “Something is missing!” (see supra § 3.2).

6. The enthymeme as a closing formula

Ancient rhetoricians considered enthymemes based on opposites to be the most efficient. This specific enthymeme has appropriated the name of the class, as its paragon,

Although every expression of thought may be called an enthymeme, the one which is based on contraries has appropriated the common name for its sole possession, for it seems the most pointed form of argument.  (Cicero, Top., XIII, 55; 423)