Triangle of opposition explained

In the system of Aristotelian logic, the triangle of opposition is a diagram representing the different ways in which each of the three propositions of the system is logically related ('opposed') to each of the others. The system is also useful in the analysis of syllogistic logic, serving to identify the allowed logical conversions from one type to another.

In the 19th and 20th centuries, other triangles were proposed, including Nicolai A. Vasiliev's triangle,^[1] the Jespersenian Triangle, Ginzberg’s triangle of contraries and Sir William Hamilton’s subcontraries.^[2]

See also

• Logical cube
• Logical hexagon
• Square of opposition

External links

Philosophy Documentation Center website A Triangle of Opposites for Types of Propositions in Aristotelian Logic, by Paul Jacoby, published in The New Scholasticism (Volume 24, Issue 1, January 1950, pages 32-56)

Notes and References

1. Web site: Non-Classical Stems from Classical: N. A. Vasiliev's Approach to Logic and his Reassessment of the Square of Opposition (Book review) . Bazhanov . Valentin . January 31, 2008 . Philosophy Documentation Center . 2024-03-05.
2. Web site: Histoire d'*O: Lexical Pragmatics and the Geometry of Opposition . Horn . Laurence . January 31, 2010 . Yale University . 2024-03-05.