"In VI, 1-3 [42-44] Plotinus severely criticizes the Aristotelian (VI, 1 , 1-24) and the Stoic (VI, 1 , 25-30) doctrines of
categories. Following in the footsteps of Plato for the Intelligible world (VI, 2 ), he proposes five categories, being, identity, otherness, movement and
repose, the "greatest kinds" of the 'Sophist'. For the sensible world he presents us with an emended and simplified system of five Aristotelian categories,
substance, quantity, quality, relation and movement (but he certainly seems to derive these latter from the Intelligible in VI, 2 , 21,24-59).
1) What are the categories of the sensible world and what is their status? Are they classifications of words, concepts or things? Does
Plotinus subordinate the Aristotelian categories to the Platonic genera or does he accept Aristotle's categories as proposed but limit their usefulness
exclusively to the domain of the sensible? Evangeliou argues that Plotinus accepted only the ontological interpretation of the Aristotelian categorical theory
and, therefore, rejected them. Anton tends more to the view that while Plotinus rejects Aristotelian doctrine, he also subordinates it to the Platonic genera
of VI, 2 . Wurm also holds the view (at the beginning of his book) that Plotinus uses Aristotle's categories to express the divisions of the sensible world
and presents them as a sort of intermediate help to the knowledge of the intelligibles, but he also contradicts this at the end of his book, which perhaps
accurately reflects Plotinus' altogether negative attitude in VI, 3 . (25)
2) How is sensible substance, then, to be related to intelligible substance? C. Rutten had argued that Plotinus' treatment of the categories
was nominalistic, that it made of his system an absolute idealism re Intelligibles, but a nominalism re sensibles. Against this mistaken, but widely accepted
thesis, Wurm has shown convincingly that Plotinus' philosophy is objective, not merely psychological, and that the objective knowledge of Intelligible entities
is the ground for the perception of sensible substances, which are a collection of qualities in matter manifesting intelligible logoi and not merely a
projection of thought upon appearances. Therefore, the charge of nominalism re sensibles is not well founded.
3) But how is homonymous sensible substance grounded in Intelligible substance? Plotinus refuses to grant that the term "substance" can be
attributed synonymously to all the substances admitted by Aristotle. But at VI, 1  3,1-5 he does suggest that we might take Intelligible substance, matter,
form and compound together as an individual category in the same way as we might say the clan of the Heracleidae constitutes one genus, in the sense that they
are all derived from one source. This would make of Intelligible substance the focal unity of the otherwise purely homonymous principles, form and matter, in
sensible things and would perhaps permit of interpretation along the lines of an Aristotelian pros hen equivocal.
Hadot, in a fascinating and extremely careful piece of detective work, (26) has uncovered, from the commentary of Dexippus on the
'Categories', a residue of a lost commentary by Porphyry on the 'Categories' and addressed to Gedalius (and transformed by lamblichus in Simplicius according
to Iamblichus' own metaphysical assumptions), in which Porphyry tried to show that the systematisation of substances in Bk. XII of the 'Metaphysics' was not
incompatible with the Plotinian doctrine of substance (Dexippus, In Categ., 40, 13 --42, 3 Busse). Aristotle speaks of three kinds of substance (two sensible
and one an immobile, Intelligible substance), Porphyry of a) sensible, composite substance, b) physical substance i.e. incorruptible substance in the light of
the incorruptible principles of the physical world, matter and form, and c) Intelligible substance (Dexippus, p. 41); and they are related in such a way that
although there is homonymy between sensible and Intelligible substance, there is also a relation of analogy based upon developments in that notion in Metaph.
XII (1070 B 30-1071 B 3) which require that all substances ultimately have reference to Intelligible substance from which they come forth (Hadot, p. 44).
Aubenque, by contrast, has stressed (1) that it is from Plato (Rep. 508 BC), and not from Aristotle, that the idea could be developed that
analogical unity is founded on the unity of convergence pros hen) or dependence (aphi enós) (27) and (2) that there is a genuinely
Aristotelian refusal (implicit in Plotinus, explicit in Proclus) to confuse focal unity and analogy and to play simultaneously on the two tableaux, the
vertical and the horizontal. Such a confusion, according to Aubenque, would be to suppress the liberty of the One in favour of "une sorte d'administration
de la procession", (73-74). This makes us see quite clearly how important is the radical gulf between Intelligible reality and its images. This concern
has also been urged by Hadot.
4) Wurm (Substanz and Qualitat, Berlin, 1973) has maintained, in a similar vein, that Plotinus only employs the Aristotelian
immanent, substantial form in such cases where there is no nearer concept. Hence, the disappearance of the substantial form in sensible substances in VI, 3
 is Plotinus' true position, perhaps a correction of his earlier avowed position in II, 6 , according to which quality may be viewed in either of two
ways: as inhering in substance it is an act, as coming after substance it is pure quality (for the 'correction' VI, 2 , 14). Strange (Diss. U. of Texas,
Austin, 1981) sees this as clear evidence for a development in Plotinus' thought. This new position where the sensible species of the object is nothing more
than the conjunction of the sensible differentiae leads to the position of the 'Isagoge' (18, 23-19, 3), that the form-species is constituted by the
sum of the differentiae. Szlezák (GGA 227, 216-225) criticizes Wurm's position; the productive logos of VI, 3 , 15, 27ff. is the
Aristotelian form, which Plotinus does not reject. One may say in review of Szlezák's view that, on the one hand, it does not square with the sharp dichotomy
of the logical treatises between Intelligible and sensible; on the other hand, however, the foundation of discourse is what is important to Plotinus here. In
VI, 1  and 3  the ultimate ground is matter and, therefore, no principle of inner organic unity can reveal itself. Perhaps then one should not reject
too strictly a place for the "psychological" in Plotinus' thinking. But there is no need because of the Platonic form of argument in VI, 103 [42-44] to
disregard genuine dialogue with Aristotle in a context elsewhere. Plotinus' thought is full of apparent inconsistencies, but the difference between II, 6 
and the logical treatises may still only be one of standpoint. Where the inquiry is founded upon Being, then quality, quantity, movement, even matter and
bodies (as Porphyry's argument in Dexippus might well be understood to claim) will be discovered "there" (VI, 2 , 21, 24-59) to be reflected later in an
ad hoc "material" classification which has already lost the focus of any objective foundation for thought.
In the views of this "new wave" of scholars, then (Wurm, Szlezák, Evangeliou, Anton, Strange, Hadot, Henry), Plotinus' treatment of the
genera of being is given a more sympathetic treatment. Anton emphasizes the importance of Plotinus' reconstruction of categorical theory for the history of the
criticism of classical Aristotelianism.
Hadot, Henry and Wurm have done most to bring about this change of attitude by locating Plotinus' written philosophy within the larger
context of Plato and Aristotle or of a Plotinian oral teaching on substance, quantity etc. in Porphyry, Dexippus and Simplicius. Thus, it has become legitimate
to ask not only (1) what does Aristotle mean, (2) how does Plotinus understand and refute him and (3) how is this viewed by later commentators, but also (4)
who is right, to what degree and in what sense. (28)" (pp. 579-581)
(25) C. Evangeliou, "The Ontological Basis of Plotinus' Criticism of Aristotle's Theory of Categories", in: The Structure of Being,
ed. R. B. Harris, Albany, N. Y. 1982, 73-82; J. Anton, "Plotinus' Approach to Categorical Theory", in: The Significance of Neoplatonism, ed. R. B.
Harris, Albany, N. Y. 1976, 83-100; K. Wurm, Substanz und Qualität, Berlin 1973.
(26) "L'harmonie des philosophies de Plotin et d'Aristote selon Porphyre", in: Plotino e il Neoplatonismo, Rome 1974, 31-47.
(27) "Néoplatonisme et analogie de l'être", in: Néoplatonisme, Cahiers de Fontenay, 1981, 63-67.
(28) P. Henry, "The Oral Teaching of Plotinus", Dionysus, 6, 1982, 4-12, cf. also Id., "Trois apories Orales de Plotin sur les
Catégories d'Aristote", in: Zetesis, 1973, 234-267.
From: Kevin Corrigan, Padraig O'Clereigh, "The Course of Plotinian Scholarship from 1971-1986". In Wolfgang Haase (ed.), Aufstieg und
Niedergang der römischen Welt (ANRW). Teil II: Principat. Band 36: Philosophie, Wissenschaften, Technik. I. Teilband: Philosophie (Historische Einleitung;
Platonismus), Berlin: Walter de Gruyter 1987, pp. 571-623.