Syllogism

A syllogism ^[1] is a deduction. It is a kind of logical argument in which one proposition (the conclusion) is inferred from two or more others (the premises).^[2] The idea is an invention of Aristotle.^[3]

In the Prior Analytics, Aristotle defines the syllogism as "a discourse in which, certain things having been supposed, something different from the things supposed results of necessity because these things are so". (24b18–20)

Each proposition must have some form of the verb 'to be' in it. A categorical syllogism is like a little machine built of three parts: the major premise, the minor premise and the conclusion. Each of these parts is a proposition and, from the first two, the "truth value" of the third part is decided.

1. ↑ Greek: συλλογισμός – syllogismos – "conclusion," "inference"
2. ↑ Frede, Michael 1975. Stoic vs. Peripatetic syllogistic. Archive for the History of Philosophy 56, 99-124.
3. ↑ Jaeger, Werner 1934. Aristotle: fundamentals of the history of his development. Oxford University Press. p370