Porphyrian tree

a) A. porphyrii from Purchotius' Institutiones philosophicae I, 1730.
b) A. porphyrii, probably from one of Boethius' translations.
c) A. scientiae (Ramon Llull) using A. porphyrii structure.
See also:
image:Arbor porphyrii according Sowa (2001) GER.png.

An arbor porphyriana or Porphyrian tree, created by Porphyry, is a hierarchical (tree structured) ontology, construction in logic consisting of three rows or columns of words; the middlemost whereof contains the series of genus and species, and bears some analogy to the trunk. The extremes, containing the differences, are analogous to the branches of a tree.

An example is

SUBSTANCE
Thinking	Extended
BODY
Inanimate	Animate
ANIMAL
Irrational	Rational
MAN
This	That
PLATO.

The tree is named after the 3rd century Greek Neoplatonist, Porphyry, who wrote an introduction to Aristotle's Categories. It was translated into Latin by Boethius 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.

Further reading

• William Stanley Jevons (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.

 This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain. Complete contents online.