User Tools

Modus Darii

A form of syllogism in which a new affirmative existential statement is derived from general and existential statements.

All M are P.
Some S are M.

Some S are P.

For example:

All squares are rectangles.
Some rhombuses are squares.

Some rhombuses are rectangles.

Name

The name “Darii” is a mnemonic term, in which the vowels (a-i-i) indicate that the first premise is an affirmative universal quantification (type “a”), and that the second premise as well as the conclusion are both affirmative existential quantifications (type “i”).

Although there is an existential statement inferred from a universal proposition in this form, no further proof of existence is needed, as the minor statement already implies existence at the intersection of S and M.

For more information on this naming scheme, and on syllogisms in general, see the article on syllogisms in the glossary.

Variants

The following forms are the variants of Modus Darii and can all be transformed back into it:

See also

More information

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