silogismos

Silogismos, or syllogisms, are deductive arguments in which the conclusion follows necessarily from two categorical premises that share a middle term. They are a central feature of Aristotelian logic, used to study how terms relate and how conclusions can be drawn from general statements.

A syllogism uses three terms: the subject term (S), the predicate term (P), and the middle term (M) that appears in both premises but not in the conclusion. The major premise links M to P, the minor premise links S to M, and the conclusion links S to P. The arrangement of these terms determines the figure of the syllogism, of which there are four classical figures, each with its own valid and invalid moods.

The mood of a syllogism describes the types of propositions involved, using the four standard forms: A (universal affirmative), E (universal negative), I (particular affirmative), and O (particular negative). A syllogism’s validity depends on both its mood and its figure. Among the best-known valid forms in Figure 1 are Barbara (AAA-1), Celarent (EAE-1), Darii (AII-1), and Ferio (EIO-1).

A common illustrative example is: All men are mortal; Socrates is a man; therefore Socrates is mortal. This follows the Barbara pattern (AAA-1) and demonstrates how a conclusion can be derived from two universal premises.

Historically, silogismos provided a formal account of inference in Western philosophy and laid groundwork for later developments in logic. Today they are studied as a historical and conceptual stepping stone to modern predicate logic, while still serving as a concise framework for teaching deductive reasoning.