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
syllogism in American English
(ˈsɪləˌdʒɪzəm)
noun
1.
an argument or form of reasoning in which two statements or premises are made and a logical conclusion is drawn from them Ex.: All mammals are warmblooded (major premise); whales are mammals (minor premise); therefore, whales are warmblooded (conclusion)
2.
reasoning from the general to the particular; deductive logic
3.
an instance of subtle, tricky, or specious reasoning
Derived forms
syllogistic (ˌsylloˈgistic)
adjective or ˌsylloˈgistical
syllogistically (ˌsylloˈgistically)
adverb
Word origin
ME silogisme < MFr < L syllogismus < Gr syllogismos, a reckoning together < syllogizesthai, to reckon together, sum up < syn-, together + logizesthai, to reason < logos, word: see logic