logical truth

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 30, 2026

Quick Summary

Logical truth refers to statements that are true by definition or by virtue of their logical form, independent of empirical facts. These truths are often called "formal truths". They are considered "a priori," meaning they are known independently of experience.123

A key concept related to logical truth is a tautology, which is a statement that cannot be denied without inconsistency. For example, "All bachelors are unmarried" is a tautology because the definition of "bachelor" includes being unmarried. The truth of such statements arises from the meanings of the words they contain, not from observations about the world.431

While empirical truths are based on observation and experiment, logical truths are considered factually empty but essential for making explicit the implications of factual assertions. They are fundamental to logic and mathematics.536

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

9 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.

$optical illusion: refraction of light$
epistemology
Logical and factual propositions
…to a proposition expressing a logical truth—e.g., to a proposition such as “If p and q, then p.” The proposition “All husbands are married,” for example, is logically equivalent to the proposition “If something is married and it is male, then it is married.” In contrast, the semantic and syntactic…
Read More
…to a proposition expressing a logical truth—e.g., to a proposition such as “If p and q, then p.” The proposition “All husbands are married,” for example, is logically equivalent to the proposition “If something is married and it is male, then it is married.” In contrast, the semantic and syntactic…
Read More