conversion simpliciter

syllogistic

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 24, 2026

Quick Summary

In syllogistic logic, conversion is the process of interchanging the subject and predicate of a categorical proposition. This operation yields a valid inference, meaning the converted proposition is equivalent to the original, primarily for universal negative (E) and particular affirmative (I) propositions.1

For example:
* The converse of "No men are immortal" is "No immortals are men" (E proposition).
* The converse of "Some man is mortal" is "Some mortal is man" (I proposition).

Universal affirmative (A) propositions can be converted, but this often requires weakening the universal quantifier to a particular one, a process known as conversion per accidens. Particular negative (O) propositions cannot be converted.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

history of logic
Categorical forms
…to be converted “simply” (simpliciter). But propositions of form A cannot be converted in this way; if every β is an α, it does not follow that every α is a β. It does follow, however, that some α is a β. Such propositions, which can be converted provided…
Read More
…to be converted “simply” (simpliciter). But propositions of form A cannot be converted in this way; if every β is an α, it does not follow that every α is a β. It does follow, however, that some α is a β. Such propositions, which can be converted provided…
Read More