«لا بد في التناقض في المحصورتين من كون القضيتين مختلفتين في الكم»
In contradiction between two quantified propositions, their quantities must also differ.
The quantifiers “all”, “none”, “some” and “some not” determine the scope of the subject. Merely changing affirmation into negation without the correct universal/particular shift may allow both propositions to have the same truth value.
The pairings are:
Universal affirmative ↔ particular negative
Universal negative ↔ particular affirmative
Both quantity and quality change, ensuring opposite truth-values under the standard assumptions of this traditional discussion.