Form of a syllogism based on the Modus Celarent, in which a negative universal proposition is inferred from an affirmative and a negative existential proposition.
All P are M.
No S is M.
[and there exists at least one S]*
Therefore, some S are not P.
For example:
All squares are rectangles.
No circle is a rectangle.
[and there exists at least one circle]*
Therefore, some circles are not squares.
Modus Camestros is similar to Modus Camestres, but is the weaker of the two forms, as it infers a existential statement rather than an universal one.
The name “Camestros” is a mnemonic term that helps to remember the most important characteristics of this mode: The “C” at the beginning indicates that it is related to the Modus Celarent, the “a” and “e” mark the affirmative and negative universal statements in the premisses, the “o” a negative existential conclusion.