Lesson 8 · The five universals I: species, genus, differentia

Source: Book pp. 31–33.

Every universal is either essential (dhātī), part of what a thing is, or accidental (ʿaraḍī), something that attaches to it. The essential ones are three: nawʿ (species), jins (genus) and faṣl (differentia). The accidental ones are two: khāṣṣa and ʿaraḍ ʿāmm (Lesson 9). Together they are the kulliyyāt khams, the five universals.

1. "Who is he?" and "What is he?"

• "Who is he?" asks about a particular person. The answer picks him out: "the son of so-and-so", "the author of such-and-such". "A human being" is a wrong answer; it does not tell him apart.
• "What is he?" (mā huwa?) asks about his reality (ḥaqīqa, māhiyya), what he shares with others like him. The right answer is "a human being".

2. Nawʿ (species)

Ask "what are these?" about Zayd, ʿUmar and Khālid. They share one complete reality and differ only as individuals. The answer, "human", is their species.

Nawʿ: the complete reality shared by individuals that differ only in individuation.

3. Jins (genus)

Ask "what are these?" about a human, a horse and an ape. They have different realities, so the answer gives the part of their reality they share: "animal". That is their genus.

Jins: the shared part of the reality of things whose realities differ.

4. Faṣl (differentia)

Now ask "what is a human?" The full answer is "a rational animal". It splits the human reality into the part shared with others (animal, the genus) and the part that is the human's alone (rational, the differentia). Genus plus differentia is the complete definition (ḥadd tāmm).

To get the differentia on its own, you ask a different question. If you see a shape in the distance and know it is an animal but not which kind, you ask: "What sort of animal is it in its essence?" (ayyu shayʾin huwa fī dhātihi?). The answer, "rational", is the differentia. If you only knew it was a body, the answer would be "sensing" (the differentia of animal).

Faṣl: the part of a thing's reality that sets it apart, given in answer to "what sort of thing is it in its essence?"

5. The ladder of genera and species

The book builds a chain from human up to substance:

substance (jawhar)          highest genus
  └ body (jism)
      └ growing body (jism nāmī)
          └ animal (ḥayawān)  proximate genus of human
              └ human (insān) lowest species
                  └ Zayd, ʿUmar, Khālid ...

Reading it upwards (genera)

• Proximate (lowest) genus, jins qarīb or sāfil: the one right above the species: animal.
• Intermediate genera, mutawassiṭ: growing body, body.
• Highest genus, jins ʿālī, the "genus of genera": substance. Nothing is above it.

Reading it downwards (species)

The word "species" has two senses:

• Real species (nawʿ ḥaqīqī): the one in the five universals, whose members differ only as individuals: human.
• Relative species (nawʿ iḍāfī): anything with a genus above it. Human, animal, growing body and body are all relative species.
  • highest species: body;
  • lowest species: human;
  • intermediate species: growing body, animal.

So every intermediate rung is a species of what is above it and a genus of what is below it. A chain of four rungs (water → liquid → body → substance) has one intermediate; a chain of five has two.

6. Kinds of differentia

• Proximate (qarīb): separates a species from what shares its nearest genus. "Rational" for human.
• Distant (baʿīd): separates it from what shares a higher genus. "Sensing" for human (separates it from plants, not from horses).
• Constitutive (muqawwim): a differentia counted as part of the species it builds. "Sensing" constitutes animal.
• Divisive (muqassim): the same differentia counted as what splits the genus above. "Sensing" divides growing bodies into the sensing and the non-sensing.

The rule: whatever constitutes the higher also constitutes the lower, but not the other way round. "Sensing" constitutes animal, so it also constitutes human and horse; "rational" constitutes human but not animal.

ʿAqīda link. The theologians agree that Allah has no ḥadd (definition by genus and differentia). A ḥadd places a thing under a genus shared with others and then marks it off; but Allah shares no reality with anything: "There is nothing like unto Him" (al-Shūrā 42:11). He is known through His names, attributes and acts, not through a definition. This is also one reason the scholars reject, or at least demand clarification of, terms like "body" (jism) when applied to Allah: in this ladder, "body" is a genus.

Quiz 8

1. Which question asks for the species, which for the genus, and which for the differentia?
2. What is the species of Zayd? The proximate genus of human? The differentia of human? The complete definition of human?
3. In the ladder substance → body → growing body → animal → human, name: the highest genus; the lowest species; the intermediates; and say what "growing body" is relative to "body" and to "animal".
4. Is "animal" a real species? A relative species? Explain.
5. Is "sensing" a proximate or a distant differentia of human? Of animal?
6. "Sensing" constitutes animal. Why must it also constitute human? Does "rational" constitute animal?
7. Why can Allah not be given a ḥadd?
8. Review: animal > human. What is the relation between non-animal and non-human?