A rhetorical syllogism, an informal instance of syllogistic or deductive reasoning, i.e. a syllogism based on “signs and likelihoods” the conclusion of which is more or less probable or plausible as opposed to being necessary (Seaton). Aristotle called the enthymeme the “’body’ of all artistic rhetorical proof, inductive as well as deductive, ethos, pathos, as well as logos” (Gage 38; Aristotle 40-47).
An enthymeme generally takes this simple form: two sentences (or propositions) where one is the reason for the other (Gage 41; Danisch 232; Emmel 132-34; Walker 54-55).
You can find examples of enthymemes at Rhetorical Figures in Sound.
An enthymeme has a grounds-claim or premise-claim structure, e.g.:
<conclusion> because of <premise>
<premise>, hence <conclusion>
<datum> so <claim> (Walker 58)
The two propositions of an enthymeme may linked explicitly with terms that signal hypotaxis or subordination, e.g. because, since, hence, therefore
The two propositions of an enthymeme may be linked implicitly or paratactically. In this the case the reader or the hearer must infer the line.
An enthymeme’s major or minor premise or the conclusion may be implied or suppressed—in fact, one or more premises probably will be suppressed and reconstructing what is implied or suggested can be instructive. This tells you what the writer or speaker predicts that he or she can assume that the audience will also assume to be true.
Hence, enthymematic reasoning is dialectical reasoning, where dialectical reasoning is defined as reasoning that begins from what a community accepts to be the case (Perelman 1-4).
A classic enthymeme will have three propositions (a major and a minor premise and a conclusion) with one or even two propositions suggested or implied as opposed to explicitly stated, and three terms within the explicit propositions. A proposition is a subject and predicate, two terms linked by a verb (Emmel 132-34). Here would be the Caesar’s famous I came, I saw, I conquered laid out in classic form with a because-clause.
I conquered (x), which is the conclusion of the enthymeme
When I arrived I correctly estimated and assessed the situation (at x), which would be our hypotactic paraphrase of the paratactic I came, I saw.
What is the purpose of laying out an enthymeme in its classic form?—the exercise clarifies the relations that obtain among the propositions and helps the reader or writer uncover the gaps or suppressed premise or premises.
What is the suppressed premise as we would interpret it?—that to correctly estimate and assess the facts of a situation will deliver victory. The implication is that
I, Caesar, am a man of action and achievement.
This follows from acting decisively based on the facts to achieve a goal. The locus in this case is simple cause and effect: because Caesar is the man that he is, victory for the Roman people is the outcome.
An effective enthymeme is functionally similar to a joke: your audience should “get it” and in this way participate in the construction of meaning. In Caesar’s case Caesar boasts of his effectiveness without explicitly saying “I am effective.” In this sense an enthymeme is a technique of indirection that calls on a community’s participation through its stock of truths or truisms to complete its meaning.
Aristotle. On Rhetoric, a Theory of Civic Discourse Trans. George A. Kennedy. New York: Oxford University Press 1991.
Danisch, Robert. “Aphorisms, Enthymemes, and Oliver Wendell Holmes, Jr. On the First Amendment.” Rhetoric Review 27.3 (2008): 219-35.
Emmel, Barbara A. “Toward a Pedagogy of the Enthymeme: The Roles of Dialogue, Intention, and Function in Shaping Argument.” Rhetoric Review 13.1 (1994): 132-49.
Gage, John T. “Teaching the Enthymeme: Invention and Arrangement.” Rhetoric Review 2.1 (1983): 38-50.
Perelman, CH. The Realm of Rhetoric Trans. William Kluback. Notre Dame: University of Notre Dame Press 1982.
Seaton, R. C. “The Aristotelian Enthymeme.” The Classical Review 28.4 (1914): 113-19.
Walker, Jeffrey. “The Body of Persuasion: A Theory of the Enthymeme.” College English 56.1 (1994): 46-65.