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The Healing, Logic: Isagoge

The opening of his great encyclopedia, where Avicenna promised to keep everything worth keeping from the ancients and to add what he had found himself.

by Avicenna133 passages held

  • Arabic, the original language
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Original title
al-Madkhal
Original language
Arabic

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Overview

For centuries every student of logic in the Greek and Arabic schools began with the same short textbook, the Isagoge (Introduction) of Porphyry, a pupil of Plotinus, which sorts the ways one word can be said of another into five: genus, species, difference, property and accident. Avicenna's al-Madkhal covers the same ground, as a fresh treatment, not a commentary, and it stands at the head of al-Shifāʾ (The Healing), the encyclopedia of philosophy he began in Hamadan at his students' request and finished in Isfahan by about 1027. Its prologue, written for the whole encyclopedia, states the scale of the plan: nothing of value in the books of the ancients is left out, and what Avicenna had worked out for himself is added, above all in physics, metaphysics and logic. The same pages admit that this book goes along with the Peripatetics, Aristotle's followers, further than he would like, and they send a reader who wants his views without that courtesy to another work, his Eastern Philosophy. In the logic itself he keeps Porphyry's five terms but drops the custom of opening logic with questions that belong to metaphysics. Chapter after chapter sets out what earlier writers had said and then corrects it, and Porphyry appears not by name but as the author of the Isagoge. One chapter separates three ways of taking a universal such as animal: as a nature in itself, as a concept in the mind, and as the logician's general term. That chapter circulated in a medieval Latin translation. Two English translations appeared within two years of each other: Allan Bäck's in 2019 and, with a new edition of the Arabic, Silvia Di Vincenzo's in 2021.

Key concepts

What are the five predicables?

They are the five ways one general term can be said of another: genus, species, difference, property and general accident. Said of a human being, animal is the genus, human the species, rational the difference, able to laugh a property belonging to humans alone, and white a general accident that humans share with many other things. Avicenna takes the list from Porphyry's Isagoge and rebuilds its justification.

What makes a feature essential rather than accidental?

An essential feature constitutes the thing: you cannot understand the thing while thinking it away, and it is prior to the thing in thought. Animal and rational are essential to a human. Everything else is accidental, even a feature that always follows from the essence, such as the triangle's having its angles equal to two right angles. Definition is built only from what is essential.

What is the difference between a natural, a mental and a logical genus?

They are one word, animal, taken three ways. The natural genus is animal considered just as animal, apart from whether it is one or many. The mental genus is animal as a concept someone holds. The logical genus is the relation that concept has, of being said of many things differing in species. Keeping them apart stops logic and metaphysics from talking past each other.

Why is a word like sun universal if only one sun exists?

Because a word is universal when its meaning, as conceived, does not rule out being shared by many, whatever the world happens to contain. Sun, moon and a solid bounded by twenty triangles each name one thing in fact, yet nothing in the idea forbids more. A proper name such as Zayd is particular because its meaning itself points to one individual.

What, on this book's account, does logic study?

Logic studies the features things acquire by existing in the mind: being a genus, being a subject or a predicate, being universal or particular. Things exist in two ways, in the world and in the mind, and these features belong only to the second. Through them the mind moves from what it knows to what it does not yet know, which is why logic serves every other science.

Themes of the book

What this book returns to, gathered into themes and ordered by how much of the text each one occupies.

Five Ways of Saying One Thing of Another

When we call a person an animal, rational, able to laugh or white, are we saying the same kind of thing each time? Everything later in logic, from definition to proof, depends on keeping these apart.

Avicenna keeps Porphyry's five terms, genus, species, difference, property and general accident, but rebuilds the ground under them. The decisive line runs between what is essential to a thing, which constitutes it and cannot be thought away, and what merely belongs to it, however reliably. Being able to laugh belongs to every human and to nothing else, yet it follows from being human rather than making one human. Chapter by chapter he states what earlier writers said about each term and then corrects them, so that definition, the work of the later books, rests on firm distinctions.

  • predication
  • definition
  • differentia
  • genus
  • species
  • predicables
  • classification
  • accidents
  • genus and species
  • properties
  • essential properties
  • general accident
  • essence

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Where Universals Live

Animal is said of every horse and every bird, but what is it that is said? The answer decides what logic studies and what it must leave to metaphysics.

Avicenna separates three ways of taking a universal. Animal considered purely as animal is a nature, and even being one comes to it from outside; animal as conceived is an idea in a mind; animal as a genus is the logician's label, a relation the idea bears to the things it is said of. Logic studies the last: features that things acquire only by being in the mind. That is why he refuses to open his logic with arguments about what really exists. Those belong to first philosophy, and he postpones them there.

  • universals
  • conception
  • metaphysics
  • correlatives

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The Encyclopedia's Promise

Can one book hold everything worth knowing that the ancients found, and still say what its author found himself? The prologue to The Healing claims both, and admits the price.

The prologue speaks for the whole of al-Shifāʾ. Nothing of value in the books of the ancients, Avicenna writes, is missing from it; whatever is not in its customary place stands where he judged it fitted better, and to it he has added what his own reflection reached, above all in physics, metaphysics and logic. He avoids long refutations of views that are plainly false. Yet he concedes that the book defers to the Peripatetics, Aristotle's school, and names another, his Eastern Philosophy, for philosophy as it is by nature, stated without regard for colleagues.

  • knowledge
  • logic

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Within this work

passages held
133
distinct concepts
110
by passages held, corpus-wide
#445

What this book thinks together

The wheel takes this book’s leading concepts and shows how often they come up together. The wider the band between two, the more of its passages speak of both. Among them, most often together: “differentia” and “essence”.
Concept co-occurrence, strongest first 8 concepts, joined by 28 pairings. 72 pairings reach beyond these concepts and are not drawn.
ConceptPaired conceptShared passages
differentiaessence22
differentiagenus22
genuspredication22
differentiapredication20
essencegenus18
genusspecies17
definitiondifferentia16
definitionpredication16
differentiaspecies16
definitionlogic15
definitiongenus14
essencepredication14
definitionessence13
predicationspecies13
genusuniversals12
predicationuniversals11
definitionspecies10
essencespecies10
essenceuniversals10
logicspecies10
logicuniversals9
speciesuniversals8
definitionuniversals7
logicpredication6
differentiauniversals5
genuslogic5
differentialogic4
essencelogic3

Works held

The author's work in order, this book marked in place. Your-language title first, the original beneath it where the two differ; side chips show which full texts are held.

  1. A Compendium on the Soul (Kitāb fī al-nafs ʿalā sunnat al-ikhtiṣār)

    The earliest of his books, written for the Sāmānid court at Bukhara before any of the summaries of philosophy that made his name.

     EN
  2. A Treatise on Love (Risāla fī māhiyyat al-ʿishq)

    Written at the request of a jurist, Abū ʿAbd Allāh al-Maʿṣūmī, and set out in seven short sections.

     AR
  3. al-Najāt

    Between the vast al-Shifāʾ and the allusive Ishārāt in both length and manner, and the usual way into his logic.

     AR
  4. al-Taʿlīqāt

    A classroom companion to his metaphysics: short notes on its key terms, read today beside al-Shifāʾ.

     AR
  5. Commentary on the Poetics of Aristotle (Fann al-Shiʿr)

    Filed under logic, as the Arabic tradition filed Aristotle's Poetics, it closes the nine logical books of al-Shifāʾ.

     AR
  6. Kitāb al-Nafs

    The fullest of his many accounts of the soul, written as natural science, and the one Latin Europe read.

     AR
  7. Kitāb al-Siyāsa

    The household branch of practical philosophy, set out for a man, his family and his servants, in a short Arabic treatise.

     AR
  8. Remarks and Admonitions (al-Ishārāt wa-l-tanbīhāt)

    Shorter than al-Najāt and far shorter than al-Shifāʾ, though written after both, as a statement of his mature philosophy.

     AR
  9. Risāla fī maʿrifat al-nafs al-nāṭiqa wa-aḥwālihā

    A short epistle in three chapters and an epilogue, one of several treatises on the soul that circulate under his name.

     AR
  10. The Healing, Logic: Isagoge (al-Madkhal) you are here AR
  11. The Metaphysics of The Healing (al-Ilāhiyyāt)

    His fullest metaphysics, known to Latin readers as the Liber de philosophia prima; it closes al-Shifāʾ after the logic, the physics and the mathematics.

     AR
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