«ويشترط في أخذ تناقض الشرطيات الاتفاق في الجنس والنوع، والمخالفة في الكيف»
To construct the contradictory of conditionals, they must agree in genus and species, while differing in quality.
Same genus: a connected conditional should be compared with the negation of that same connected relation, or a disjunctive with the same disjunctive relation.
Same species: the relation involved, such as an entailment rather than a coincidence, must not be silently changed.
Different quality: the whole judgment is affirmed in one and denied in the other.
Merely denying a component is not necessarily denying the conditional as a whole.