The Artful Geometry of Logic

A research team has amassed a collection of Aristotelian diagrams created between the years of 830 and 2021 and have placed them online.

As part of a research program on logical geometry, Lorenz Demey a philosopher at KU Leuven, his colleague in linguistics, Hans Smessaert, and others have organized the images into a searchable website—the Leuven Ontology for Aristotelian Diagrams Database—with over 3200 diagrams.

Many of the diagrams are straightforward depictions of the square of opposition, but there are a variety of others, some of which are rather artistic. Below are varied samples of some of the more interesting-looking ones (ordered chronologically). Click on the images for further information at their pages in the database:

Diagram by Lucius Apuleius (901-1000)


Diagram by Notker Labeo (1001-1050)


Diagram by Johannes Fabri and Allardus Tassart (1500-1505)


Diagram by Alonso de la Veracruz (1569)


Diagram by Henricus Joannes van Cantelbeke, Petrus Damman, and Andreas Blanche (1669)


Diagram by Augustinus Vandungen and Lambert-Jean Beauvoix (1759)


Diagram by John Neville Keynes (1894)


Diagram by W.E. Johnson (1921)


Diagram by Hans Reichenbach (1952)


Diagram by Pierre Sauriol (1968)


Diagram by Thomas Becker (1997)


Diagram by Ulla Wessels (2002)


Diagram by Régis Pellissier (2008)


Diagram by Jean-Pierre Desclés and Anca Pascu (2012)


Diagram by Juan Manuel Campos Benítez (2017)

You can check out the entire database here.


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Aeon J. Skoble
1 year ago

I love this. I used to include that Octagon of Opposition from JN Keynes’ 1894 book in my intro logic classes, actually.