Enthymeme

An enthymeme (Greek: ἐνθύμημα, enthumēma), 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, or a less-than-100% argument.

Explanation

Here is an example of an informal syllogism, an enthymeme:

• "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)

While syllogisms lay out all of their premises and conclusion explicitly, enthymemes keep at least one of the premises or conclusion unsaid. The assertions left unsaid are intended to be so obvious as to not need stating.

Advice is given freely because so much of it is worthless.

—James Geary

Here it is an explicit premise that 1) advice is given freely. But an implicit premise is that only worthless things are given away freely.

Here is an example of a "a less-than-100% argument" stated by George Bernard Shaw:

The reasonable man adapts himself to the world.

The unreasonable one persists in trying to adapt the world to himself.

Therefore all progress depends on the unreasonable man.

While all the premises are true, it is arguable that a man is "unreasonable" because he is trying to change the world.

See also

• Chewbacca defense
• Fallacy
• Rogerian argument
• Senator, you are no Jack Kennedy
• modus ponens

External links

• Extensive bibliography of enthymeme in scholarly literature
• The enthymeme in modern speech
• Audio illustrations of enthymeme