Ancient Greek logic

Dialectic (; ), also known as the dialectical method, refers originally to dialogue between people holding different points of view about a subject but wishing to arrive at the truth through reasoned argument. Dialectic resembles debate, but the concept excludes subjective elements such as emotional appeal and rhetoric; the object is more an eventual and commonly held truth than the "winning" of an (often binary) competition. It has its origins in ancient philosophy and continued to be developed in the Middle Ages.

A syllogism (, syllogismos, 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true.

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thought experiment concerning the continuity of identity of an item which has all its parts replaced

thumb|Organon thumb|Roman copy in marble of a Greek bronze bust of Aristotle by Lysippos, c. 330 BC, with modern alabaster mantle

philosophical paradox

statement of a liar who states that they are lying: for instance, declaring that "I am lying" or "everything I say is false"

ancient socratic school

Adiaphoron (; plural: adiaphora; from the Greek (pl. ), meaning 'not different or differentiable') is the negation of diaphora, 'difference'.

logical paradox involving self-reference

work by Aristotle

Classic device

paradox originating in ancient Greece, often cited for humorous purposes to signal the "race of speciosity" between forensic and political categories

Aristotle's logical theory

term

type of intensional definition, and it is composed of two parts (genus (or family) and differentia)

"Apodictic", also spelled "apodeictic" (, "capable of demonstration"), is an adjectival expression from Aristotelean logic that refers to propositions that are demonstrably, necessarily or self-evidently true. Apodicticity or apodixis is the corresponding abstract noun, referring to logical certainty.

proposition that asserts or denies that all or some of the members of one category are included in another

Diairesis (, "division") is a form of classification used in ancient (especially Platonic) logic that serves to systematize concepts and come to definitions. When defining a concept using diairesis, one starts with a broad concept, then divides this into two or more specific sub-concepts, and this procedure is repeated until a definition of the desired concept is reached. Aristotle makes extensive use of diaresis in categorization as basis for syllogizing. He makes clear, however, that definition by diaresis does not in itself prove anything. Apart from this definition, the procedure also resu

in philosophy: an act of judgement where one term is subsumed under another

Assertoric is an adjectival expression in Aristotelian logic that refers to propositions which merely assert that something is (or is not) the case. Assertoricity is the corresponding abstract noun.