An arbor porphyriana or Porphyrian tree, created by Porphyry

Porphyry (philosopher)

Porphyry of Tyre , Porphyrios, AD 234–c. 305) was a Neoplatonic philosopher who was born in Tyre. He edited and published the Enneads, the only collection of the work of his teacher Plotinus. He also wrote many works himself on a wide variety of topics...

, is a hierarchical

Hierarchy

A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

 (tree structure

Tree structure

A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree, even though the chart is generally upside down compared to an actual tree, with the "root" at the top and the...

d) ontology

Ontology

Ontology is the philosophical study of the nature of being, existence or reality as such, as well as the basic categories of being and their relations...

, construction in logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

 consisting of three rows or columns of words; the middlemost whereof contains the series of genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 and species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, and bears some analogy to the trunk

Trunk (botany)

In botany, trunk refers to the main wooden axis of a tree that supports the branches and is supported by and directly attached to the roots. The trunk is covered by the bark, which is an important diagnostic feature in tree identification, and which often differs markedly from the bottom of the...

. The extremes, containing the differences, are analogous to the branches of a tree.

An example is

!colspan="2" align="center"|SUBSTANCE
|-
|align="left"|Thinking
|align="right"|Extended
|-
!colspan="2" align="center"|BODY
|-
|align="left"|Inanimate
|align="right"|Animate
|-
!colspan="2" align="center"|ANIMAL
|-
|align="left"|Irrational
|align="right"|Rational
|-
!colspan="2" align="center"|MAN
|-
|align="left"|This
|align="right"|That
|-
!colspan="2" align="center"|PLATO.
|-
|}

The tree is named after the 3rd century Greek Neoplatonist, Porphyry, who wrote an introduction to Aristotle

Aristotle

Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

's Categories. It was translated into Latin by Boethius

Anicius Manlius Severinus Boethius

Anicius Manlius Severinus Boëthius, commonly called Boethius was a philosopher of the early 6th century. He was born in Rome to an ancient and important family which included emperors Petronius Maximus and Olybrius and many consuls. His father, Flavius Manlius Boethius, was consul in 487 after...

 and became the standard philosophical textbook in the Middle Ages.

In his introduction, Porphyry presented the basis of Aristotle's thought as a tree-like scheme of dichotomous divisions, which indicates that a species is defined by genus-differentia and that the process continues until the lowest species is reached.

The arbor porphyriana has also been known as scala praedicamentalis. Until the late 19th century, it was still being taught to students of logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

.

Further reading

• William Stanley Jevons
  William Stanley Jevons
  William Stanley Jevons was a British economist and logician.Irving Fisher described his book The Theory of Political Economy as beginning the mathematical method in economics. It made the case that economics as a science concerned with quantities is necessarily mathematical...
  
  (1870). Elementary Lessons in Logic. London.
• Paul Richard Blum (1999). Dio e gli individui: L' Arbor Porphyriana nei secoli XVII e XVIII. Rivista di filosofia neo-scolastica 91: 18-49.

Complete contents online.