Enthymeme ἐνθύμημα
An enthymeme is a rhetorical inference that rests on the probable rather than the necessary, and in which one premise is often left unstated because the audience is expected to fill it in for itself. Aristotle called the enthymeme the syllogism of rhetoric and saw it, together with the example, as the most important form of logos.
The syllogism of rhetoric
Aristotle distinguishes between two ways of arguing in rhetoric, corresponding to the two basic forms of logic. The example corresponds to induction: a conclusion is drawn from a particular case. The enthymeme corresponds to deduction: from a general rule, a conclusion is drawn about a particular case.
But the enthymeme is simpler than the inferences of dialectic. Dialectic takes place between two partners in conversation who both master the method. Rhetoric is addressed to a broad audience that cannot follow long chains of reasoning, and that must also take a position on things that can be otherwise: the future, the past, what is right.
The unstated premise
An enthymeme does not need to say everything. “We need tougher sentences for violent crime” rests on a rule that the speaker does not state but that the audience is assumed to share: that harsh punishment deters. Aristotle’s own example is even shorter. To show that the athlete Dorieus has won a crown, it is enough to say that he has been victorious at Olympia. Everyone already knows that the victors at Olympia receive a crown.
It is precisely the unstated premise that makes the enthymeme strong. The audience takes part in the inference by filling in what is missing, and what it has thought for itself it seldom questions. But that is also where criticism should begin: what is taken for granted, and does it hold?
Probabilities and signs
According to Aristotle, enthymemes rest either on the probable, what is usually the case, or on signs. “If the internet gives more people the chance to express themselves, democracy is likely to be strengthened” is an argument from probability. “If social media cause stress, that is a sign that they are harmful” rests on a sign.
Some signs are certain: someone who has a fever is ill. Others are uncertain: rapid breathing may mean fever, but also that the person has just been running.
Topoi for enthymemes
Where do we find the general rules that enthymemes rest on? Aristotle answers with the doctrine of topoi. In the Rhetoric he lists 28 topoi on which enthymemes can be built, among them contraries, the greater and the lesser, and consequence. Read more about topos.
The apparent enthymeme
Enthymemes can also be apparent: they look as if they hold, but they do not. One of Aristotle’s examples is what was later called post hoc ergo propter hoc, the assumption that what comes after something is also caused by it. When the Athenian politician Demades claimed that Demosthenes’ policy had caused Athens’ misfortunes in the war against Macedon, it was possible, perhaps even probable, but not necessary.
Questions
What is an enthymeme?
A rhetorical inference that rests on the probable and often leaves a premise unstated, because the audience is expected to fill it in.
What is the difference between an enthymeme and a syllogism?
A syllogism is logically valid: if the premises are true, the conclusion must be true. An enthymeme rests on probabilities and on what the audience already believes, and it often leaves a premise unstated.
What is an example of an enthymeme?
“She’ll surely make a good manager, she used to be a teacher.” The unstated premise is that someone who can lead a class can also lead a workplace.
