The Five Predicables: Genus, Species and Hierarchy of Genera

1. Introducing the five predicables

A universal may be predicated of multiple individuals. The next issue is how a universal relates to the nature of the things of which it is said.

The five predicables are:
1. Genus (jins)
2. Species (naw‘)
3. Differentia (fasl)
4. Property (khassah)
5. Common accident (‘arad ‘amm)

All five are universals, but they stand in different relations to essence. This level develops genus and species first. The other three receive their own treatment later.

2. Essence and the what-is-it question

Mahiyyah (essence) is the nature by which a thing is identified for purposes of logical classification. The question “ma huwa?” asks what something is in its nature.

Ask what a human, a horse and a sheep are: the shared answer is animal. Ask what Zayd and Amr are: the answer is human.

Both are answers to what-is-it questions. But the first covers things of different specific natures, whereas the second covers individuals of the same specific nature.

3. The source definition of genus

الجنس وهو كلي مقول على كثيرين مختلفين بالحقائق في جواب «ما هو؟»
A genus is a universal said of many things differing in their specific natures, in answer to “What is it?”

The definition includes four elements: universality, plurality, differences of specific nature, and being a reply to the what-is-it question.

Animal is predicated of humans, horses and sheep. Their species-natures differ, but the generic aspect of animality belongs to each.

4. Why animal is a genus

Consider three living beings:
Human — an animal with the distinctive nature of a human.
Horse — an animal of a different species.
Sheep — an animal of another species.

These beings have different specific essences: human cannot simply mean horse or sheep. Yet animal is shared by all three as a constituent of their classification by nature.

A genus is therefore not merely a convenient shared label. It signifies something common within the essences of different species.

5. Why differing essences matter

“Differing in essences” does not simply mean varying in height, age or colour. Zayd and Amr may differ in those respects, yet both share the same human species-nature.

Human and horse differ at the level of species; animal is the generic nature shared between these different species.

Zayd, Amr, Khalid: distinct persons of one species.
Human, horse, sheep: distinct species under the genus animal.

6. Predicating a genus correctly

When we say “al-insan hayawan” (human is animal), we classify the human species under the genus animal. Animality is not an accidental feature external to the human essence.

Every human is an animal: true in this classification.
Every animal is a human: false; horses and sheep are animals too.

This recalls absolute inclusion: the extension of animal is wider than that of human.

7. The source definition of species

النوع وهو كلي مقول على كثيرين متفقين بالحقائق في جواب «ما هو؟»
A species is a universal predicated of many things agreeing in their specific essences, in response to “What is it?”

The genus definition says differing in essences, while the species definition says agreeing in essences. This is the critical contrast.

Zayd, Amr and Khalid differ as persons but share the human essence. Human answers what each is; hence it functions as species.

8. Why human is a species

Zayd and Amr are distinct persons. Their age, habits and physical appearance may vary.

Nevertheless, they agree in the specific human nature. Thus human is a universal predicated of numerous individuals sharing one species-essence.

Human is species for Zayd and Amr; animal is genus for human and horse, because these have different specific essences.

9. One essence, distinct individuals

Agreement in essence does not mean that all members of a species are identical in every attribute. Were that so, Zayd and Amr could not be distinguished as persons.

Species-level agreement concerns basic nature. Individuals can vary in their individuating and accidental attributes.

Two humans: same species despite different heights.
Human and horse: different species despite both being animals.

Keeping these levels distinct prevents genus and species from being confused.

10. Comparing genus and species

Both genus and species are universals and both can answer “What is it?” Their roles differ.

Genus: identifies a shared essential element among different species.
Species: identifies the common specific essence of multiple individuals of one species.

Question: What are human and horse?
Answer: Animal — genus.
Question: What are Zayd and Amr?
Answer: Human — species.

We must attend to the relevant level of predication, not only the isolated word.

11. How predicables are classified

A universal may state an essential nature, express a part of that nature, or signify a characteristic external to it. The five predicables analyze these different relationships.

Genus: a shared essential component of distinct species.
Species: the specific nature common to individuals of one kind.

Differentia, property and common accident will be classified in detail in later passages. Merely applying to many individuals does not by itself make a universal a genus.

12. Real species

The universal predicated of multiple individuals agreeing in specific essence is called a real species (naw‘ haqiqi). “Real” here refers to their common species-nature.

Human: a real species for Zayd, Amr and Khalid.
Horse: a real species for individual horses.

Ask whether the individuals under discussion agree in specific essence. If they do, their shared species-title satisfies this account.

13. The relative sense of species

وللنوع معنى آخر، ويقال له: النوع الإضافي
Species also has a second meaning, called relative species.

A relative species (naw‘ idafi) is considered with reference to a higher genus: a broader genus is predicated of it and of other distinct natures alongside it.

Human is a relative species under animal, because animal applies to humans and to other species such as horses.

14. Why species is called relative

“Relative” means that the classification is made in relation to a broader genus.

Human → animal: human is a species under animal.
Animal → growing body: animal is a narrower kind under growing body.

Thus being a relative species describes a hierarchical relation. A concept can be a species relative to something above while also being genus relative to what lies below.

15. When a species is both real and relative

Human qualifies in both ways.

Real species: Zayd, Amr and other humans agree in one specific nature.
Relative species: human stands under the wider genus animal, alongside horse and other distinct species.

There is no contradiction. Real species focuses on the essence shared by its individuals; relative species focuses on its relation to a broader genus.

16. Real species without relative species

The printed commentary gives point (nuqtah) as an example for distinguishing real species from relative species. Multiple points can be considered to agree in the nature of point, allowing its classification as a real species in this account.

In this logical treatment, a higher genus combining it with further distinct species is not assumed. Thus being a real species does not entail being a relative species.

This example follows the source's particular conceptual taxonomy, rather than making an unrestricted claim about every modern physical account of points.

17. Relative species without real species

Animal encompasses different species-natures such as human, horse and sheep. It is therefore not a real species for that whole collection: the individuals do not all agree in one species-essence.

However, animal is a relative species under the broader growing body, which also includes vegetation in the classical hierarchy.

Being a relative species does not therefore automatically make a concept a real species.

18. Partial overlap between the two kinds of species

وبين النوع الحقيقي والنوع الإضافي عموم وخصوص من وجه
Real species and relative species overlap partially (general and particular in one respect).

Three regions are involved:
Both: Human — real and relative species.
Real only: Point — in the source commentary's taxonomy.
Relative only: Animal — relative to growing body, but a genus of distinct species beneath it.

This applies the previously learned relation of partial overlap to logical terminology.

19. Why genera have ranks

Some genera occur below other genera and above still narrower genera or species. They therefore occupy different ranks in a hierarchy.

Body → growing body → animal → human

In this classical order:
Body — broader category.
Growing body — narrower than body.
Animal — narrower than growing body.
Human — a species under animal.

A middle term can function as genus relative to what lies below and as relative species with respect to what lies above.

20. Lowest genus

The lowest genus (jins safil) has a genus above it but no further genus below it; below it lie species.

Example: animal.
The genus growing body stands above animal, while human is a species below it. In this chain animal is the lowest genus.

“Lowest” denotes a structural rank in the genus series, not lesser worth or importance.

21. Intermediate genus

An intermediate genus (jins mutawassit) has a genus above it and a genus below it.

Example: growing body.
Body stands above it, while animal stands below it. This makes growing body an intermediate genus.

Unlike the lowest genus, an intermediate genus still has another genus beneath it, rather than only species.

22. Highest genus and genus of genera

The highest genus (jins ‘ali) has no further genus above it within the hierarchy. It is also called genus of genera (jins al-ajnas).

The source uses substance (jawhar) as its example. Body, growing body and animal occupy lower ranks beneath substance in this classification.

The three ranks—highest, intermediate and lowest—describe positions in an ordered hierarchy, rather than three unrelated kinds of essence.

23. All three genus ranks in one chain

Read this classical series:
Substance → body → growing body → animal → human

Substance: highest genus; no higher genus in the series.
Body: intermediate genus; substance above, growing body below.
Growing body: intermediate genus; body above, animal below.
Animal: lowest genus; a genus above, species such as human below.
Human: in this series a real and relative species, not a further genus.

The hierarchy reflects the source's classical logical classification.

24. A genus can also be a relative species

Animal enters two different relations:
Relative to human and horse: it is their genus, common to different species.
Relative to growing body: it is a relative species beneath a broader genus.

There is no contradiction, because the two descriptions refer to different directions within a hierarchy. A term can be genus downward and relative species upward.

The relevant higher and lower terms must therefore be specified.

25. Applying the definitions

Apply four questions to any case:
1. Is the term universal or an individual name?
2. Of which things is it given in reply to “What is it?”
3. Do those things agree or differ in specific essence?
4. Does the term also stand below a broader genus, making it a relative species?

Animal, relative to human and horse: genus.
Human, relative to Zayd and Amr: real species.
Animal, relative to growing body: relative species.

The classification changes when the relation under examination changes.

26. Worked corrections to misconceptions

Misconception 1: Any shared attribute is a genus.
Correction: A genus expresses an essential element common to distinct species, not merely an accidental similarity such as colour.

Misconception 2: A word must always be either genus or species.
Correction: Animal is genus relative to human and horse, yet relative species under growing body.

Misconception 3: Every real species must also be relative species.
Correction: The commentary uses point as real-only and animal as relative-only to demonstrate partial overlap.

27. Synthesis and the next section

Genus: a universal predicated in answer to “What is it?” of beings differing in their specific essences.
Real species: a universal similarly predicated of individuals agreeing in specific essence.
Relative species: a narrower nature situated beneath a wider genus alongside other kinds.
Relation between real and relative species: partial overlap.
Ranks of genera: highest, intermediate and lowest.

Do not merely memorize the labels. In each example identify the relevant items, whether their natures agree or differ, and the genus or species immediately above or below.

The next section turns to the highest genera and ten categories.