«زيد أب أي لبكر، وزيد ليس بأب أي لخالد»
Zayd is Bakr's father, and Zayd is not Khalid's father.
Both may be true. Fatherhood is a relational predicate: we must ask, “father of whom?” The first relation is to Bakr, the second to Khalid.
A contradictory pair would be:
“Zayd is Bakr's father.”
“Zayd is not Bakr's father.”
Here the other term of the relation is identical. An identical relational word is insufficient unless its object is identical too.
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Contradiction: Definition, Conditions and Application to Propositions
«زيد أب أي لبكر، وزيد ليس بأب أي لخالد»
Zayd is Bakr's father, and Zayd is not Khalid's father.
Both may be true. Fatherhood is a relational predicate: we must ask, “father of whom?” The first relation is to Bakr, the second to Khalid.
A contradictory pair would be:
“Zayd is Bakr's father.”
“Zayd is not Bakr's father.”
Here the other term of the relation is identical. An identical relational word is insufficient unless its object is identical too.