Modus Darapti

Form of a syllogism based on the Modus Darii, in which an affirmative existential proposition is inferred from two affirmative universal premisses. This form has an additional existential requirement.

All M are P.

All M are S.

[and there exists at least one M]*

∴ Some S are P.

For example:

All squares are rectangles.

All squares are polygons.

[and there exists at least one square]*

∴ Some polygons are rectangles.

* Note: When an existential conclusion is inferred from universal premisses, this requires an (implicit or explicit) existential import, i.e. it must be proven that what the term refers to actually exists. In case of the Modus Darapti it is sufficient to prove existence for the middle term (M), as this also implies existence of both S and P.

Modus Disamis is very similar to the modi Datisi and Disamis, except that it is based on two universal statements in the premisses, rather than a universal and an existential statement each.

The name “Darapti” is a mnemonic term that helps to remember the most important characteristics of this mode: The “D” at the beginning indicates that it is related to the Modus Darii, the two “a” and the “i” indicate that affirmative universal and existential statements make up this form.

• Existential import
• Existential quantification
• Modus Darii
• Syllogism
• Universal quantification