Authors/Ockham/Summa Logicae/Book III-1/Chapter 66

Latin	English
Cap. 66. De syllogismo facto ex exclusivis	Chapter 66. On syllogisms made from exclusives.
Circa exclusivas est sciendum quod in prima figura ex omnibus exclusivis contingit inferre exclusivam. Sicut sequitur 'tantum homo currit; tantum album est homo; igitur tantum album currit'. Similiter ex maiore exclusive et minore universali non sequitur conclusio, nec particularis nec universalis. Sicut non sequitur 'tantum animal est homo; omnis asinus est animal; igitur aliquis asinus est homo'. Sed ex maiore universali et minore exclusiva sequitur conclusio particularis, sed non conclusio exclusiva.	Regarding exclusives, it should be noted that in the first figure it is possible to infer an exclusive from all exclusives. As follows 'only a man runs; only a white thing is a man; therefore only a white thing runs'. Similarly, from an exclusive major and a universal minor no conclusion follows, neither particular nor universal. As it does not follow: 'only an animal is a man; every donkey is an animal; therefore, some donkey is a man'. But from a universal major and an exclusive minor a particular conclusion follows, but not an exclusive conclusion.
In secunda figura ex omnibus exclusivis non sequitur exclusiva. Sicut non sequitur 'tantum animal est homo; tantum non-homo non est homo; igitur tantum non-homo non est animal'. Non enim sequitur 'tantum ens est homo; tantum non-homo non est homo; igitur tantum non-homo non est ens', quia infert istam 'non-homo non est ens', cum eius opposita sit vera 'omnis non-homo est ens'.	In the second figure, an exclusive does not follow from all exclusives. Just as it does not follow that 'only an animal is a man; only a non-man is not a man; therefore only a non-man is not an animal'. For it does not follow that 'only a being is a man; only a non-man is not a man; therefore only a non-man is not a being', because it infers that 'a non-man is not a being', since its opposite is true 'every non-man is a being'.
In tertia figura ex omnibus exclusivis non sequitur exclusiva; quia non sequitur 'tantum animal est homo; tantum animal est asinus; igitur tantum asinus est homo'. Nec sequitur 'igitur asinus est homo', sicut nec ex duabus universalibus affirmativis sequitur conclusio in secunda figura. Si autem maior sit universalis et minor exclusiva, sequitur conclusio particularis. ƿ	In the third figure, no exclusive follows from all exclusives; because it does not follow that 'only an animal is a man; only an animal is a donkey; therefore only a donkey is a man'. Nor does it follow that 'therefore a donkey is a man', just as no conclusion follows from two affirmative universals in the second figure. But if the major is universal and the minor exclusive, a particular conclusion follows.