syllogism

[ sil-uh-jiz-uhm ]

noun

1. Logic. an argument the conclusion of which is supported by two premises, of which one major premise contains the term major term that is the predicate of the conclusion, and the other minor premise contains the term minor term that is the subject of the conclusion; common to both premises is a term middle term that is excluded from the conclusion. A typical form is “All A is C; all B is A; therefore all B is C.”
2. deductive reasoning.
3. an extremely subtle, sophisticated, or deceptive argument.

syllogism

/ ˈsɪləˌdʒɪzəm /

noun

1. a deductive inference consisting of two premises and a conclusion, all of which are categorial propositions. The subject of the conclusion is the minor term and its predicate the major term; the middle term occurs in both premises but not the conclusion. There are 256 such arguments but only 24 are valid. Some men are mortal; some men are angelic; so some mortals are angelic is invalid, while some temples are in ruins; all ruins are fascinating; so some temples are fascinating is valid. Here fascinating, in ruins, and temples are respectively major, middle, and minor terms
2. a deductive inference of certain other forms with two premises, such as the hypothetical syllogism, if P then Q; if Q then R; so if P then R
3. a piece of deductive reasoning from the general to the particular
4. a subtle or deceptive piece of reasoning

Word History and Origins

Origin of syllogism¹

1350–1400; < Latin syllogismus < Greek syllogismós, equivalent to syllog- ( syllogize ) + -ismos -ism; replacing Middle English silogime < Old French < Latin, as above

Word History and Origins

Origin of syllogism¹

C14: via Latin from Greek sullogismos, from sullogizesthai to reckon together, from sul- syn- + logizesthai to calculate, from logos a discourse

Example Sentences

In his book "Prior Analytics," Aristotle works out the logic of “the categorical syllogism.”

From Salon

A syllogism is any argument that has a conclusion supported by two premises.

From Salon

A syllogism is “categorical” if the conclusion and two premises are of categorical form, that is, is a sentence of the type “All A are B,” “No A are B,” “Some A are B,” or “Some A are not B.”

From Salon

It turns out that there are 256 ways to arrange three categorical sentences into a syllogism.

From Salon

A categorical syllogism includes three categories, call them A, B, and C. One premise would involve A and B, the other would relate B and C, and then the conclusion would be a statement about A and C. So, if we were going to move from representing single propositions to illustrating the entire syllogism, we need a new sort of diagram, the one with three interlocking circles that Vice President Harris is so enamored with.

From Salon