فصل في النسبة بين الكليين: اعلم أن النسبة بين الكليين تتصور على أنحاء أربعة؛
Section on the relation between two universals: know that four kinds of relation are possible between two universal concepts.
“Relation” here refers to the range of things to which each meaning applies, not to how similar the words sound or look. The words “human” and “animal” differ in form; that is not the question. We ask which individuals fall under each meaning.
The four relations are:
1. Equality: exactly the same instances.
2. Disjointness: no common instances.
3. Absolute inclusion: everything under one concept falls under the other, but not conversely.
4. Overlap in one respect: some common and some exclusive instances on each side.