User Tools

Modus Bocardo

Form of a syllogism based on the Modus Barbara, in which a negative existential proposition is inferred from another negative existential and a positive universal proposition.

Some M are not P.
All M are S.

Some S are not P.

For example:

Some rectangles are not squares.
All squares are polygons.

Some polygons are not squares.

The Modus Bocardo and the Modus Baroco are the only two modes that require an indirect proof of validity in order to be reducible to their general form (the Modus Barbara). In fact, these two modes are identical, except that the premises are in reverse order.

Name

The name “Bocardo” is a mnemonic term that helps to remember the most important characteristics of this mode: The “B” at the beginning indicates that it is related to the Modus Barbara, the two “o” stand for negative existential and the “a” for an affirmative universal statement. The “c” in the name indicates that the transformation to the basic form requires further proof of validity.

See also

About this site

Ad Hominem Info is a project to explain and categorize the most common systematic fallacies and fallacies. On this page, you will find a background article that briefly explains an important logical concept, which may be needed to better understand another article in this area.
For more information, please see the main category “logic

This website uses cookies. By using the website, you agree with storing cookies on your computer. Also, you acknowledge that you have read and understand our Privacy Policy. If you do not agree, please leave the website.

More information