Syl'lo-gĭsm, n.

n. [Fr. syllogisme, Lat. syllogismus, Gr. συλλογισμός, a reckoning all together, a reasoning, from συλλογίζεσθαι, to reckon all together, to bring at once before the mind, to infer, conclude, from σὺν, with, together, and λογίζεσθαι, to reckon, to conclude by reasoning. See LOGISTIC.] (Logic.) The regular logical form of every argument, consisting of three propositions, of which the first two are called the premises, and the last the conclusion. The conclusion necessarily follows from the premises; so that, if these are true, the conclusion must be true, and the argument amounts to demonstration; as in the following example:— A plant has not the power of locomotion; An oak is a plant; Therefore an oak has not the power of locomotion. These propositions are denominated respectively the major, the minor, and the conclusion. ☞ If the premises are not true, and the syllogism is regular, the reasoning is valid, and the conclusion, whether true or false, is correctly derived.