Terminlogik

Terminlogik, or term logic, is a branch of classical logic concerned with the logical relations between terms within categorical propositions. It originated in Aristotle's syllogistic, often described as the logic of terms, because reasoning proceeds through terms (the subject, the middle term, and the predicate) rather than directly through arguments about individuals.

Core notions include terms (classes or concepts), distribution (whether a term is asserted of all members of a class), and categorical propositions (universal or particular, affirmative or negative). In a syllogism, two premises containing three terms yield a conclusion about the relation between the two extreme terms. Syllogistic is organized into figures and moods; famous valid forms include Barbara, Celarent, and Cesare, illustrating patterns such as All S are P, All M are S, therefore All S are P.

Historically, Terminlogik played a central role in medieval and early modern logic; it provided the groundwork for formal classification and reasoning about universals. In modern logic, the advent of first-order predicate logic with quantifiers and variables has largely supplanted term logic for general reasoning. Nevertheless, Terminlogik remains of interest in the study of Aristotelian logic, the history of logic, and certain applications in semantic theory and ontology where relationships between unary terms are central.

See also Aristotle's syllogistic, categorical proposition, and predicate logic.