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.
Origin
1350-1400; < Latinsyllogismus < Greeksyllogismós, equivalent to syllog- (see syllogize) + -ismos-ism; replacing Middle Englishsilogime < Old French < Latin, as above
(logic) the premise of a syllogism containing the predicate of its conclusion
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 Origin
C14: via Latin from Greek sullogismos, from sullogizesthai to reckon together, from sul-syn- + logizesthai to calculate, from logos a discourse
late 14c., from Old French silogisme "a syllogism," from Latin syllogismus, from Greek syllogismos "a syllogism," originally "inference, conclusion, computation, calculation," from syllogizesthai "bring together, premise, conclude," literally "think together," from syn- "together" (see syn-) + logizesthai "to reason, count," from logos "a reckoning, reason" (see logos).