A System of Logic

work by Mill

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 14, 2026

Quick Summary

John Stuart Mill's A System of Logic (1843) introduced five methods for experimental reasoning, known as Mill's methods. These methods aim to identify causal relationships between events.

The core methods include:
* Method of Agreement: Identifies factors consistently present when an effect occurs.
* Method of Difference: Pinpoints a factor present when an effect occurs and absent in a similar situation where it does not.
* Joint Method: Combines agreement and difference.
* Method of Residues: Attributes the unexplained part of an effect to remaining circumstances.
* Method of Concomitant Variation: Links variations in an effect to variations in a specific factor.1

Mill's work was influential in the development of logic, building upon earlier traditions and contributing to the broader philosophical landscape of the 19th century.234

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

4 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.

John Stuart Mill
Public life and writing of John Stuart Mill
A System of Logic, in two volumes, was published in 1843 (3rd–8th ed., introducing many changes, 1851–72). Book VI is his valiant attempt to formulate a logic of the human sciences—including history, psychology, and sociology—based on causal explanation conceived in Humean terms.
Read More
A System of Logic, in two volumes, was published in 1843 (3rd–8th ed., introducing many changes, 1851–72). Book VI is his valiant attempt to formulate a logic of the human sciences—including history, psychology, and sociology—based on causal explanation conceived in Humean terms.
Read More

Western philosophy
Positivism and social theory in Comte, Mill, and Marx
…is in his enormously influential A System of Logic (1843), however, that Mill’s chief theoretical ideas are to be found.
Read More
…is in his enormously influential A System of Logic (1843), however, that Mill’s chief theoretical ideas are to be found.
Read More

positivism
The social positivism of Comte and Mill
In his System of Logic (1843), he developed a thoroughly empiricist theory of knowledge and of scientific reasoning, going even so far as to regard logic and mathematics as empirical (though very general) sciences. The broadly synthetic philosopher Herbert Spencer, author of a doctrine of the “unknowable”…
Read More
In his System of Logic (1843), he developed a thoroughly empiricist theory of knowledge and of scientific reasoning, going even so far as to regard logic and mathematics as empirical (though very general) sciences. The broadly synthetic philosopher Herbert Spencer, author of a doctrine of the “unknowable”…
Read More