Aristotle - The Organon - index for TOPICA Book 4 Part 2

Species falling under more than one genus

Paragraph 1	Look and see, also, if there be any other genus of the given species which neither embraces the genus rendered nor yet falls under it, e.g. suppose any one were to lay down that 'knowledge' is the genus of justice.
Paragraph 2	Look, also, at the genus of the genus rendered, and so continually at the next higher genus, and see whether all are predicated of the species, and predicated in the category of essence:
Paragraph 3	Again, look among the things of which the given species is predicated as genus, and see if what is rendered as its genus be also predicated in the category of essence of the very things of which the species is so predicated, and likewise if all the genera higher than this genus are so predicated as well.
Paragraph 4	Look, also, at the definitions of the genera, and see whether they apply both to the given species and to the objects which partake of the species.
Paragraph 5	Again, see if he has rendered the differentia as the genus, e.g. 'immortal' as the genus of 'God'.
Paragraph 6	Also, see whether he has placed the differentia inside the genus, e.g. by taking 'odd' as a 'number'.
Paragraph 7	Moreover, see whether he has placed the genus inside the species, e.g. by taking 'contact' to be a 'juncture', or 'mixture' a 'fusion', or, as in Plato's definition, 'locomotion' to be the same as 'carriage'.
Paragraph 8	Again, see whether he has placed the differentia inside the species, by taking (e.g.) 'immortal' to be 'a god'.
Paragraph 9	Again, if no differentia belonging to the genus be predicated of the given species, neither will the genus be predicated of it;