1. ENTHYMEME.
An enthymeme is a syllogism in which one of the three propositions is omitted.
Suppressing the major premise gives an enthymeme of the first order; whereas if the minor premise be suppressed, the enthymeme becomes one of the second order; while omitting the conclusions gives an enthymeme of the third order.
Illustrations:
Complete syllogism.
All true teachers are just,
You are a true teacher,
(Hence) You are just.
Enthymeme of first order; major premise omitted.
..........................
You are a true teacher,
(Hence) You are just.
Enthymeme of second order; minor premise omitted.
All true teachers are just,
..........................
(Hence) You are just.
Enthymeme of the third order; conclusion omitted.
All true teachers are just,
(And) You are a true teacher,
..........................
To argue in terms of the complete syllogism is the unusual, not the usual method. We have a way of abbreviating our remarks; expressing only the necessary and leaving the obvious to be taken for granted. Thus the enthymeme becomes the natural form of expression. But the mere fact that a part of the argument is omitted, makes it more essential for the student to think clearly and with careful continuity, that no error may intrude itself.
Probably the most common enthymemes are those of the first order. This may be explained by the fact that the major premise is usually the most universal of the three propositions, and, in consequence, the one which would be the most generally understood. The following represent enthymemes of this order, gleaned from the ordinary conversation of ordinary people:
(1) “Your beets won’t grow, because you are planting them in the wrong time of the moon.”
(2) “You, being a member of the Sunday School, should be ashamed of such language.”
(3) “Being the son of your father, you ought to have some pride in this matter.”
(4) “We are going to have an open winter, because I have observed that the hornets’ nests are near the ground.”
(5) “You had better put in lots of coal, for I have noticed that the squirrels have gathered in more nuts than usual.”
Judging from these enthymemes, it would seem to be more natural to assert the conclusion and follow this bya reason in the form of a minor premise, leaving the major to the intelligence of the auditor.
The enthymeme of the second order occurs only infrequently, since it seems to be an unnatural mode of expression, though sometimes it appears to lend emphasis to the conclusion; e. g., “All untrustworthy boys come to a bad end, and I predict that you will come to a bad end.”
Enthymemes of the third order are commonly used for the sake of emphasis, as the following make evident:
(1) “No business man wants an indolent boy, and you are indolent.”
(2) “All successful teachers are interested in their work, and you plan to be a successful teacher.”
(3) “Humility is a sign of greatness, and Lincoln possessed this quality.”