Diairesis (, "division") is a form of

classification Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

used in

ancient Ancient history is a time period from the beginning of writing and recorded human history through late antiquity. The span of recorded history is roughly 5,000 years, beginning with the development of Sumerian cuneiform script. Ancient h ...

(especially Platonic)

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure o ...

that serves to systematize concepts and come to definitions. When defining a concept using diairesis, one starts with a broad concept, then divides this into two or more specific sub-concepts, and this procedure is repeated until a definition of the desired concept is reached.

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

makes extensive use of diaresis in categorization as basis for syllogizing. He makes clear, however, that definition by diaresis does not in itself prove anything. Apart from this definition, the procedure also results in a

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

of other concepts, ordered according to a general–specific relation. The founder of diairesis as a method was

Plato Plato ( ; Greek language, Greek: , ; born BC, died 348/347 BC) was an ancient Greek philosopher of the Classical Greece, Classical period who is considered a foundational thinker in Western philosophy and an innovator of the writte ...

. Later ancient logicians (including Aristotle) and practitioners of other ancient sciences have employed diairetic modes of classification, e.g., to classify plants in ancient

biology Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...

Plato's method of definition

Diairesis is Plato's later method of

definition A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitio ...

based on division, developed in the Platonic dialogues '' Phaedrus'', ''

Sophist A sophist () was a teacher in ancient Greece in the fifth and fourth centuries BCE. Sophists specialized in one or more subject areas, such as philosophy, rhetoric, music, athletics and mathematics. They taught ''arete'', "virtue" or "excellen ...

'', ''

Statesman A statesman or stateswoman is a politician or a leader in an organization who has had a long and respected career at the national or international level, or in a given field. Statesman or statesmen may also refer to: Newspapers United States ...

'', and ''

Philebus The ''Philebus'' (Φίληβος, ''Phílēbos'') is a work by the ancient Greek philosopher Plato, written in dialogue form. It presents a fictional conversation between Plato's teacher Socrates and two young Athenians, Philebus and Protarchu ...

''. Further applications are found in the ''

Laws Law is a set of rules that are created and are law enforcement, enforceable by social or governmental institutions to regulate behavior, with its precise definition a matter of longstanding debate. It has been variously described as a Socia ...

'' and '' Timaeus''. It is a means of attempting to reach a definition by which a collection of candidates is repeatedly divided into two parts with one part eliminated until a suitable definition is discovered. A complementary term is ''merismos'' (cf. English

merism Merism (, ) is a rhetorical device (or figure of speech) in which a combination of two ''contrasting parts'' of the whole refer to the whole. For example, in order to say that someone "searched everywhere", one could use the merism "searched hig ...

: parsing or the distinguishing of parts, as opposed to ''diairesis'', which is the division of a genus into its parts). For example, in the ''Sophist'' (§235B), the Eleatic Stranger is examining illusions, which consist of words and "visual objects." By using ''diairesis'', he divides visual objects, by which it becomes clear he means works of art, into two categories: ''eikastikē technē'', the art of making likenesses or ''eikones''; and ''phantastikē technē'', the art of creating illusionary appearances. The Stranger is much more fond of the former; the latter is only created to produce an appearance of beauty.

The method of ''diairesis'' in the history of philosophy

Forerunners of Plato

Opinions about possible forerunners of Platonic ''diairesis'' are varying; they even reach back until

Homer Homer (; , ; possibly born ) was an Ancient Greece, Ancient Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Despite doubts about his autho ...

. Also an adoption from the fields of mathematics has been considered, like one from musicology, one from pre-scientific and everyday divisions and one from medicine. About forerunners in the field of philosophy there are as well different opinions. Under consideration are Prodicus of Ceos,

Democritus Democritus (, ; , ''Dēmókritos'', meaning "chosen of the people"; – ) was an Ancient Greece, Ancient Greek Pre-Socratic philosophy, pre-Socratic philosopher from Abdera, Thrace, Abdera, primarily remembered today for his formulation of an ...

Leucippus Leucippus (; , ''Leúkippos''; ) was a pre-Socratic Greek philosopher. He is traditionally credited as the founder of atomism, which he developed with his student Democritus. Leucippus divided the world into two entities: atoms, indivisible ...

, and the

sophists A sophist () was a teacher in ancient Greece in the fifth and fourth centuries BCE. Sophists specialized in one or more subject areas, such as philosophy, rhetoric, music, athletics and mathematics. They taught ''arete'', "virtue" or "excellen ...

. It was even suggested that Plato says that he himself found the new method, which shows that it is possible that Plato had no forerunners at all.

Later exponents of the method of ''diairesis''

The platonic method of division is found to be applied at the first steps of classifying biology, namely in the zoology of

and in the botany of

Theophrastus Theophrastus (; ; c. 371 – c. 287 BC) was an ancient Greek Philosophy, philosopher and Natural history, naturalist. A native of Eresos in Lesbos, he was Aristotle's close colleague and successor as head of the Lyceum (classical), Lyceum, the ...

. Diairesis is central to

Galen Aelius Galenus or Claudius Galenus (; September 129 – AD), often Anglicization, anglicized as Galen () or Galen of Pergamon, was a Ancient Rome, Roman and Greeks, Greek physician, surgeon, and Philosophy, philosopher. Considered to be one o ...

's therapeutics; see for example 'Therapeutics to Glaucon' 1 (XI, 4 K), where Galen, attributing the method to Plato, asserts that 'the errors of the edicalsects and whatever mistakes the majority of physicians make in the care of the sick have incompetent division as their principal and major cause' (tr. Dickson.) Philosophically relevant methodical divisions or statements about the method of ''diairesis'' can be found in members of the Platonic Academy (especially

Speusippus Speusippus (; ; c. 408 – 339/8 BC) was an ancient Greece, ancient Greek philosopher. Speusippus was Plato's nephew by his sister Potone. After Plato's death, c. 348 BC, Speusippus inherited the Platonic Academy, Academy, near age 60, and remai ...

and

Xenocrates Xenocrates (; ; c. 396/5314/3 BC) of Chalcedon was a Greek philosopher, mathematician, and leader ( scholarch) of the Platonic Academy from 339/8 to 314/3 BC. His teachings followed those of Plato, which he attempted to define more closely, of ...

), of the

Peripatetic school The Peripatetic school ( ) was a philosophical school founded in 335 BC by Aristotle in the Lyceum in ancient Athens. It was an informal institution whose members conducted philosophical and scientific inquiries. The school fell into decline afte ...

(especially

Aristoxenus Aristoxenus of Tarentum (; born 375, fl. 335 BC) was a Ancient Greece, Greek Peripatetic school, Peripatetic philosopher, and a pupil of Aristotle. Most of his writings, which dealt with philosophy, ethics and music, have been lost, but one musi ...

), of

Stoicism Stoicism is a school of Hellenistic philosophy that flourished in ancient Greece and Rome. The Stoics believed that the universe operated according to reason, ''i.e.'' by a God which is immersed in nature itself. Of all the schools of ancient ...

(especially

Chrysippus Chrysippus of Soli (; , ; ) was a Ancient Greece, Greek Stoicism, Stoic Philosophy, philosopher. He was a native of Soli, Cilicia, but moved to Athens as a young man, where he became a pupil of the Stoic philosopher Cleanthes. When Cleanthes ...

), of

Middle Platonism Middle Platonism is the modern name given to a stage in the development of Platonic philosophy, lasting from about 90 BC – when Antiochus of Ascalon rejected the scepticism of the new Academy – until the development of neoplatonis ...

(especially

Alcinous In Greek mythology, Alcinous (also Alcinoüs; ; ''Alkínoos'' ) was a son of Nausithous and brother of Rhexenor. After the latter's death, he married his brother's daughter Arete who bore him Nausicaa, Halius, Clytoneus and Laodamas. In ...

, Maximus of Tyre,

Philo Philo of Alexandria (; ; ; ), also called , was a Hellenistic Jewish philosopher who lived in Alexandria, in the Roman province of Egypt. The only event in Philo's life that can be decisively dated is his representation of the Alexandrian J ...

) and of

Neoplatonism Neoplatonism is a version of Platonic philosophy that emerged in the 3rd century AD against the background of Hellenistic philosophy and religion. The term does not encapsulate a set of ideas as much as a series of thinkers. Among the common id ...

(especially

Plotinus Plotinus (; , ''Plōtînos''; – 270 CE) was a Greek Platonist philosopher, born and raised in Roman Egypt. Plotinus is regarded by modern scholarship as the founder of Neoplatonism. His teacher was the self-taught philosopher Ammonius ...

, Porphyry). In medieval times the so-called method of ''divisio'' was a common method.(german) Hans Leisegang: ''Denkformen'', Walter de Gruyter, Berlin 1951, p. 252

References

External links

* {{Authority control Classification systems Concepts in ancient Greek epistemology Concepts in logic Definition Term logic Ancient Greek logic Philosophical methodology Platonism Rhetorical techniques Stoicism Concepts in ancient Greek metaphysics