Enthymeme
An enthymeme (Greek: ἐνθύμημα, enthumēma), in its modern sense, is an informally stated syllogism (a three-part deductive argument) with an unstated assumption that must be true for the premises to lead to the conclusion. In an enthymeme, part of the argument is missing because it is assumed. In a broader usage, the term "enthymeme" is sometimes used to describe an incomplete argument of forms other than the syllogism,[1] or a less-than-100% argument.[2] For Aristotle, who defined it in his Rhetoric, an enthymeme was a "rhetorical syllogism" which was based on probable opinions, thus distinguishing it from a scientific syllogism. It is aimed at persuasion while scientific syllogism is aimed at demonstration.[3] This definition of an enthymeme held fast until the 20th century, when Saul Kripke developed Modal logic. In the context of Modal logic, with Semantic tableaux as developed by Evert Willem Beth, the definition of an enthymeme alters: Rather than suppressing one of the major premises, minor premises, or the conclusion, any incorrect logical inference or proof that is persuasive, satisfies a concept of an enthymeme.
Contents |
[edit] Formal requirements
While syllogisms lay out all of their premises and conclusion explicitly, enthymemes keep at least one of the premises or conclusion unsaid. The assertion left unsaid is intended to be so obvious as to not need stating.[4]
Thus, enthymemes allow the speaker both to avoid alienating listeners with long chains of inferences and appeal to the audience's common sense without depleting the argument any of its logical force. For instance, a lawyer might say: "Only she had the means, the motive and the opportunity to kill him. She must be the killer." Logically, what's missing? A connection between the statements, which we tend to fill in automatically. Something like "The killer had the means, motive and opportunity to kill him." But a lawyer who spelled this detail out to the jury might be considered pedantic.
Though they require some filling in, enthymemes are intended to have the form of valid deductive syllogisms, so a complete enthymeme has the same premise-premise-conclusion structure as any syllogism, and is intended to guarantee the truth of its conclusion based on the truth of its premises.
Hence the argument...
P1: Only she had the means, the motive and the opportunity to kill him.
P2: The one with the means, motive and opportunity to kill him is the killer. (unstated)
C: She must be the killer.
...is clearly valid and deductive when the unstated premise is made explicit. But leaving the second premise to the imagination of the jurors is more appealing from a rhetorical standpoint. [4]
[edit] Order
There are three conventional orders of enthymemes. A first-order enthymeme suppresses the major premise. A second-order enthymeme suppresses the minor premise. A third-order enthymeme suppresses the conclusion. Other orders of enthymemes, in which 2 elements of the syllogism are suppressed, could be postulated.
[edit] Examples
[edit] Informal syllogism
- "Socrates is mortal because he's human."
- The complete syllogism would be the classic:
-
- All humans are mortal. (major premise - assumed)
- Socrates is human. (minor premise - stated)
- Therefore, Socrates is mortal. (conclusion - stated)
[edit] Maxim, or a less-than-100% argument
- Klamer et al. argue in their 2007 paper that Aristotle addressed enthymemes as maxims:
"Aristotle noted that most arguments take the form of an 'enthymeme' ('EN-thu-miem'), an incomplete or not-quite-air-tight syllogism. 'Free trade is good' or 'Taxes reduce output' are enthymemes, not-syllogistic arguments. The average French economist may find such arguments 45 percent true, whereas the average American economist may find them 80 percent true. Arguing an enthymeme is successful when the economist defends the 45 or 80 percent true as 'true enough.' Economics, like other sciences, works in approximations."[2]
[edit] See also
[edit] References
- ^ Audi, R. (ed.), The Cambridge Dictionary of Philosophy - 2nd ed., pp. 257, 267. Cambridge University Press, 1999.
- ^ a b Klamer, Arjo; McCloskey, Deirdre N. and Ziliak, Stephen (18 May 2007). "Is There Life after Samuelson's Economics? Changing the Textbooks". Post-Autistic Economics Review (Post-autistic Economics Network) (42): 2–7. http://www.paecon.net/PAEReview/issue42/KlamerMcCloskeyZiliak42.pdf. Retrieved 2009-05-18.
- ^ Aristotle, Rhetoric, book I, 1 and 2
- ^ a b http://plato.stanford.edu/entries/aristotle-rhetoric/#enthymeme
[edit] External links
 |
Look up enthymeme in Wiktionary, the free dictionary. |
 |
Wikisource has the text of the 1911 Encyclopædia Britannica article Enthymeme. |
