Term Logic

Definition

Term logic is the classical form of logic used by the followers of Aristotle (i.e. all of Europe) prior to the advent of modern predicate logic. A basic knowledge of it is fundamental to understanding European and Greek philosophical texts written prior to around the mid-1800s. I have written this page as a set of notes for myself to assist with formulating the structure of the enthymemes presented in Rhetoric.

Propositions

There are four categories of propositions in term logic

• A: Universal affirmative
• E: Universal negative
• I: Particular affirmative
• O: Particular negative

Relations of Propositional Categories

A to E — Negation

Universal affirmatives and universal negatives stand in the most important dialectical relationship: they cannot both be true.

I to O — Subcontradiction

Particular affirmatives and particular negatives may simultaneously be true, but they cannot simultaneously be false.

A to I / E to O— Implication

The universal affirmative implies the particular affirmative; likewise for the universal and particular negative.

A to O / E to I — Contradiction

The universal affirmative contradicts the particular negative; likewise for the universal negative and the particular positive.

Syllogistic Dialectic

Where R is one of the aforementioned relations.

Modus Ponens (Affirming the Antecedent)

Modus Tollens (Denying the Consequent)

Sources

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Last Modified: May 9, 2019