Porphyrian tree

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

[edit] References

• This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain. [1]
• S. Jevons (1870). Elementary Lessons in Logic. London.