will be seen, Plotinus prefers to call the sensible being Becoming (τό γινόμενον), in contrast to real Being (τό 8v).29
These four points clearly indicate the direction and strategy of Plotinus' discussion and criticism of Aristotle's categories. He will view the doctrine from his own metaphysical scheme and will contrast it to Plato's theory of the maxima genera. With the necessary adaptations and qualifications he will attempt to find a place for each of these doctrines in his system.
Having examined some of Plotinus' more general objections to Aristo tle's categorial doctrine, I can proceed now to examine his doubts with regard to each particular category. I will begin at the beginning, that is, with the category of ούσία.
a. Plotinus on Substance
In the next two chapters (2 and 3) of the present tract (VI. 1.) Plotinus considers the first Aristotelian category and tries to discover the sense in which ρύσία can be considered as one of the genera of Being. First of all, he excludes the possibility of there being a single entity embracing the substances of both the sensible and the intelligible realms on the ground that such a hypothesis leads to absurdities. For:
That there cannot be one common substantiality applying to both intelligi ble and sensible substance has been said already. And besides, there will [if this is so] be something before both intelligible and sensible substance, which is something else and is predicated of both, and this could not be either body or bodyless: for [if it is] body will be bodyless, or the bodyless body. (VI. 1. 2, 2-8)
Plotinus proposes that, if we restrict our investigations within the realm of the sensible existents, it may be possible to determine the common ground which is shared by all entities designated as substances, that is, ' 'matter, form and the composite of both."3 0 The problem is that these
entities are not equal "in respect of substance" because "it is said that form is more substance than matter—quite correctly: but there are those who would say that matter is more substance" (VI. 1. 2, 10-12).31
29 Enneads VI. 2. 1, 32-33; and Timaeus 27d, "Tt τό δν άεί, γένεσιν δέ ούκ εχον, καί τί
τό γιγνόμενον μέν άεί, δν 8' ούδέποτε." Compare this to Metaphysics 1028b 2-4, regarding the question τί τό δν?
30 Note here that Plotinus does not stay within the limits of the sensible substances.
From ούσιαι νοηταί he goes all the way down to the components of ούσίαι αίσθηταί.
31 The Stoics are evidently meant here. Chapters 24-30 are devoted to the criticism
Then comes the Aristotelian distinction between primary and secon dary substances which Plotinus finds questionable. He observes: "But what could the substances which they call primary have in common with the secondary ones, when the secondary ones derive their name of substances from those prior to them?" {Ibid. 12-13). As we have seen, in the Categories Aristotle calls primary substances such individuals as "a man" and "a horse." The species and genera of the individual substances are called secondary substances. Plotinus cannot accept this doctrine. As a pure Platonist, he thinks that priority must be given to the intelligibles in which the species and genera are included. On this subject Porphyry, it may be recalled, tried to do justice to both schools, the Peripatetic and the Platonic, by utilizing the distinction between "prior by perception" and "prior by nature."32
There remain two points which Plotinus discussed against the thesis that substance cannot be one single genus: (a) its indefinability and (b) the fact that what are stated as its characteristics (ϊδια) are not "applicable to all substances alike" (VI. 1. 2, 15-18). Now, this line of criticism is, to say the least, curious. For if substance is a summum genus and if a defini tion, in its Aristotelian sense, is the outcome of the blending of the genus and the differentiae, then it is obvious that ούσία cannot be defined. For there is no genus, which is higher than the definiendum itself, to serve as the starting point (άρχή) of its definition. So, strictly speaking, it is impossible to define substance, as Porphyry has pointed out in his Com
mentary.33 The conclusion of all this questioning of Plotinus seems to be
that substance cannot be a "genus" in the sense of there being a "com mon characteristic" (κοινόν τι) shared equally by all these entities which are named after it.34
This is the reason why Plotinus attempts another approach in the third chapter. He seeks a more suitable meaning of the term 'genus.' For 'genus* may mean not only "that which is predicated essentially of many things differing in species" but also the "common origin" out of which many offspring come, i.e. the genus of the Heraclids. He explains:
But ought we really to call substance one category, collecting together intelligible substance, matter, form and the composite of both? This would be like saying that the genus [or clan] of the Heraclids was a unity, not in the sense of a unity common to all its members, but because all come from one common ancestor: for the intelligible substance would be so primarily,
32 See Chapter Three above, section 1, subsection a. 33 PAC, passim, especially pp. 93-94.
34 About the different meanings of the term 'genus' see Metaphysics 1024 a 29-b 16; and Isagoge, pp. 1-2.
PLOTINUS' CRITICISM OF ARISTOTLE'S CATEGORIES 101
and the others secondarily and less. But what prevents all things from being one category? For everything else which is said to exist derives from substance. (VI. 1. 3, 1-7)
So, in the final analysis, even this alternative must be rejected. The reason which Plotinus gives for this rejection is that, if accepted, it would give the impression that everything can be included in a single genus, which is not acceptable. For Plotinus is convinced that there are many genera, and his test is to determine their correct number. He is prepared to make a concession: "Let all the so-called substances, certainly, be akin in this way and have something over and above the other genera" (VI. 1. 3, 10-12). But what is this "something?" Is it perhaps to be found among those characteristics which Aristotle had adduced and which Plotinus enumerates in VI. 1. 3, 12-19? Consider his conclusion:
But one might say that these are peculiar properties of substances as com pared with other things, and for this reason one might collect them into one and call them substances, but one would not be speaking of one genus, nor would one yet be making clear the concept and nature of substance. {Ibid. 19-23)
To put the matter in another way, Plotinus seems to argue as follows: Aristotle's definition of genus is not applicable to his category of substance which is, after all, indefinable. It would seem that ούσία αίσθητή lacks "the unity of a genus" and its nature remains unknown as far as Aristotle's theory of categories is concerned. Therefore, Aristotle was mistaken in considering sensible substance as "a genus of Being." According to Plotinus, the most one can say about it is that the sensible so-called substance has the unity of a category. This pattern of argument is repeated in the discussions of the other Aristotelian so-called "genera."
There is no doubt that Plotinus' criticism of the category of substance, considered as a "genus of Being," is very acute. Aristotle had used the term 'genus' in both his logical and his ontological treatises.35 In a critical
way, Plotinus applies what Aristotle says about genera in his Topics to the
Metaphysics and draws certain logical implications. His point is that one
is forced either to reject the use of γένος as Aristotle defined it or else to admit that the categories cannot be called "genera." He chose the second alternative for obvious reasons.
35 In Topics 102a 32-33, 'genus' is defined as follows: "γένος δ' έστί τό κατά πλειόνων
καί διαφερόντων τω εΐδει έν τω τί έστι κατηγορούμενον". Also, 108b 22-23; Metaphysics 995b 29, 998b 15, 999a 31 and elsewhere.
b. Plotinus on Quantity
The next two chapters (4 and 5) are devoted to Aristotle's category of quantity (ποσόν). In order to follow Plotinus' criticism it may help to recall that Aristotle distinguishes in the Categories (4b 20-5b 11) seven dif ferent types of ποσά which he classifies as continuous quantities and discrete quantities.36 It is this classification which Plotinus questions first:
But now, if they are going to say that the continuous is a quantum in so far as it is continuous, the discontinuous would not be a quantum: but if the continuous is a quantum incidentally, what is this being quantitative which is common to both? (VI. 1. 4, 5-8)
Plotinus proceeds to accept numbers (άριθμοί) as quantities, though he remarks that it is not clear "what their nature is in virtue of which they are called quanta" (VI. 1.4, 10). However, he has some difficulty in see ing how geometrical magnitudes (μεγέθη), such as lines, planes and solids can be considered as quantities, which was Aristotle's view. If they become quanta by being measured, then, Plotinus thinks, they are called
quanta not essentially but accidentally. He reasons:
On the other hand, line and surface and body are not called quantities; they are called magnitudes: They become known as quantities only when they are rated by number—two yards, three yards. Even the natural body becomes a quantity when measured, as does the space which it occupies; but this is quantity accidental, not quantity essential; what we seek to grasp is not accidental quantity but Quantity independent and essential, Quantity-Absolute. Three oxen is not a quantity; it is their number, the three, that is Quantity; for in three oxen we are dealing with two categories.37 (VI. 1. 4, 10-19)
According to Plotinus' argument, what Aristotle called ποσά belong really to two categories; for "two yards," "three oxen," and "a line of a certain length" are only accidental quantities, since these expressions involve two separate categories, that is, numbers and substances which happen to be "so and so" when measured or counted. The same is true with regard to mathematical bodies (solids), surfaces and lines which become known as quantities only when measured, that is, only when they are limited by number. This being the case, it seems reasonable for Plotinus to assert that magnitudes are classed as quantities: "Not because they are so in the strict sense, but because they approximate to Quantity, and because objects in which magnitudes inhere are
36 See Chapter III, section 2.
37 In Categories chapter 6, Aristotle used the same distinction in a somewhat different
sense. MacKenna's translation of this passage is much clearer than Armstrong's and preferable.