Porphyrian tree



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



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

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