The Basic Works of Aristotle (Modern Library Classics) (138 page)

¹
Cf. vii. 1.

²
Cf. vii. 2.

³
Cf. vii. 3. 1028
^b
33–6.

⁴
Cf. vii. 4–6, 12, 15.

⁵
Cf. vii. 10, 11.

⁶
Cf. vii. 13, 14, 16. 1040
^b
16–1041
^a
5.

⁷
Cf. xiii and xiv.

⁸
sc
. in the case of destruction.

⁹
sc
. in the case of generation.

¹⁰
Cf.
Phys
. 225
^a
12–20,
De Gen, et Corr.
317
^a
17–31.

¹¹
Cf. i. 985
^b
13–19.

¹²
sc
. whether the name means the form or the concrete thing.

¹³
Aristotle returns to the subject discussed in ch. 2.

¹⁴
Cf. v. 1017
^b
14–15.

¹⁵
Cf. vii. 8.

¹⁶
sc
. and therefore cannot give the essence, which is simple.

¹⁷
The Pythagoreans and Platonists (Cf. xiii. 6, 7).

¹⁸
sc
. material cause.

¹⁹
i. e. the substratum of a substance is bare matter, but the substratum of an attribute is a determinate substance such as the moon.

²⁰
sc
. the efficient cause.

²¹
Cf. vii. 12, viii. 1044
^a
2–6.

²²
Cf. vii. 1029
^b
28,
de Int.
18
^a
19.

²³
i. e. it was the essence of the potential ball to become an actual ball, and of the actual ball to be produced from a potential ball.

²⁴
Aristotle does not give the whole definition, but only the genus, or ‘material’ element.

²⁵
Cf.
^a
23–33.

1
     We have treated
¹
of that which
is
primarily and to which all the other categories of being are referred—i. e. of substance.
(30)
For it is in virtue of the concept of substance that the others also are said to be—quantity and quality and the like; for all will be found to involve the concept of substance, as we said in the first part of our work.
²
And since ‘being’ is in one way divided into individual thing, quality, and quantity, and is in another way distinguished in respect of potency and complete reality,
(35)
and of function, let us now add a discussion of potency and complete reality. And first let us explain potency in the strictest sense, which is, however, not the most
useful
for our present purpose.
[1046a]
For potency and actuality extend beyond the cases that involve a reference to motion. But when we have spoken of this first kind, we shall in our discussions of actuality
³
explain the other kinds of potency as well.

We have pointed out elsewhere
⁴
that ‘potency’ and the word ‘can’ have several senses.
(5)
Of these we may neglect all the potencies that are so called by an equivocation. For some are called so by analogy, as in geometry we say one thing is or is not a ‘power’ of another by virtue of the presence or absence of some relation between them. But all potencies that conform to the same type are originative sources of some kind,
(10)
and are called potencies in reference to one primary kind of potency, which is an originative source of change in another thing or in the thing itself
qua
other. For one kind is a potency of being acted on, i. e. the originative source, in the very thing acted on, of its being passively changed by another thing or by itself
qua
other; and another kind is a state of insusceptibility to change for the worse and to destruction by another thing or by the thing itself
qua
other by virtue of an
originative source of change. In all these definitions is implied the formula of potency in the primary sense.
(15)
—And again these so-called potencies are potencies either of merely acting or being acted on, or of acting or being acted on
well
, so that even in the formulae of the latter the formulae of the prior kinds of potency are somehow implied.

Obviously, then, in a sense the potency of acting and of being acted on is one (for a thing may be ‘capable’ either because it can itself be acted on or because something else can be acted on by it),
(20)
but in a sense the potencies are different. For the one is in the thing acted on; it is because it contains a certain originative source, and because even the matter is an originative source, that the thing acted on is acted on, and one thing by one, another by another; for that which is oily can be burnt, and that which yields in a particular way can be crushed;
⁵
and similarly in all other cases.
(25)
But the other potency is in the agent, e. g. heat and the art of building are present, one in that which can produce heat and the other in the man who can build. And so, in so far as a thing is an organic unity, it cannot be acted on by itself; for it is one and not two different things. And ‘impotence’ and ‘impotent’ stand for the privation which is contrary to potency of this sort,
(30)
so that every potency belongs to the same subject and refers to the same process as a corresponding impotence. Privation has several senses; for it means (1) that which has not a certain quality and (2) that which might naturally have it but has not it, either (
a
) in general or (
b
) when it might naturally have it, and either (α) in some particular way, e. g. when it has not it completely, or (
β
) when it has not it at all. And in certain cases if things which naturally have a quality lose it by violence,
(35)
we say they have suffered privation.

2
     Since some such originative sources are present in soulless things, and others in things possessed of soul, and in soul, and in the rational part of the soul, clearly some potencies will be non-rational and some will be accompanied by a rational formula.
[1046b]
This is why all arts, i. e. all productive forms of knowledge, are potencies; they are originative sources of change in another thing or in the artist himself considered as other.

And each of those which are accompanied by a rational formula is alike capable of contrary effects,
(5)
but one non-rational power produces one effect; e. g. the hot is capable only of heating, but the medical art can produce both disease and health. The reason is that science is a rational formula, and the same rational formula explains a thing and
its privation, only not in the same way; and in a sense it applies to both,
(10)
but in a sense it applies rather to the positive fact. Therefore such sciences must deal with contraries, but with one in virtue of their own nature and with the other not in virtue of their nature; for the rational formula applies to one object in virtue of that object’s nature, and to the other, in a sense, accidentally. For it is by denial and removal that it exhibits the contrary; for the contrary is the primary privation,
(15)
and this is the removal of the positive term. Now since contraries do not occur in the same thing, but science is a potency which depends on the possession of a rational formula, and the soul possesses an originative source of movement; therefore, while the wholesome produces only health and the calorific only heat and the frigorific only cold,
(20)
the scientific man produces both the contrary effects. For the rational formula is one which applies to both, though not in the same way, and it is in a soul which possesses an originative source of movement; so that the soul will start both processes from the same originative source, having linked them up with the same thing.
⁶
And so the things whose potency is according to a rational formula act contrariwise to the things whose potency is non-rational; for the products of the former are included under one originative source, the rational formula.
(25)

It is obvious also that the potency of merely doing a thing or having it done to one is implied in that of doing it or having it done
well
, but the latter is not always implied in the former: for he who does a thing well must also do it, but he who does it merely need not also do it well.

3
     There are some who say, as the Megaric school does, that a thing ‘can’ act only when it is acting, and when it is not acting it ‘cannot’ act,
(30)
e. g. that he who is not building cannot build, but only he who is building, when he is building; and so in all other cases. It is not hard to see the absurdities that attend this view.

For it is clear that on this view a man will not be a builder unless he is building (for to be a builder is to be able to build), and so with the other arts.
(35)
If, then, it is impossible to have such arts if one has not at some time learnt and acquired them, and it is then impossible not to have them if one has not sometime lost them (either by forgetfulness or by some accident or by time; for it cannot be by the destruction of the
object
,
⁷
for that lasts for ever), a man will not have the
art when he has ceased to use it, and yet he may immediately build again; how then will he have got the art? And similarly with regard to lifeless things; nothing will be either cold or hot or sweet or perceptible at all if people are not perceiving it; so that the upholders of this view will have to maintain the doctrine of Protagoras.
⁸
[1047a]
But,
(5)
indeed, nothing will even have perception if it is not perceiving, i. e. exercising its perception. If, then, that is blind which has not sight though it would naturally have it, when it would naturally have it and when it still exists, the same people will be blind many times in the day—and deaf too.

Again, if that which is deprived of potency is incapable,
(10)
that which is not happening will be incapable of happening; but he who says of that which is incapable of happening either that it is or that it will be will say what is untrue; for this is what incapacity meant. Therefore these views do away with both movement and becoming.
(15)
For that which stands will always stand, and that which sits will always sit, since if it is sitting it will not get up; for that which, as we are told, cannot get up will be incapable of getting up. But we cannot say this, so that evidently potency and actuality are different (but these views make potency and actuality the same, and so it is no small thing they are seeking to annihilate), so that it is possible that a thing may be capable of being and not
be
,
(20)
and capable of not being and yet
be
, and similarly with the other kinds of predicate; it may be capable of walking and yet not walk, or capable of not walking and yet walk. And a thing is capable of doing something if there will be nothing impossible in its having the actuality of that of which it is said to have the capacity.
(25)
I mean, for instance, if a thing is capable of sitting and it is open to it to sit, there will be nothing impossible in its actually sitting; and similarly if it is capable of being moved or moving, or of standing or making to stand, or of being or coming to be, or of not being or not coming to be.

The word ‘actuality’, which we connect with ‘complete reality’,
(30)
has, in the main, been extended from movements to other things; for actuality in the strict sense is thought to be identical with movement. And so people do not assign movement to non-existent things, though they do assign some other predicates. e. g. they say that nonexistent things are objects of thought and desire, but not that they are moved; and this because, while
ex hypothesi
they do not actually exist,
(35)
they would have to exist actually if they were moved. For of non-existent things some exist potentially; but they do not
exist
, because they do not exist in complete reality.
[1047b]

4
     If what we have described
⁹
is identical with the capable or convertible with it, evidently it cannot be true to say ‘this is capable of being but will not be’,
(5)
which would imply that the things
in
capable of being would on this showing vanish. Suppose, for instance, that a man—one who did not take account of that which is incapable of being—were to say that the diagonal of the square is capable of being measured but will not be measured, because a thing may well be capable of being or coming to be, and yet not be or be about to be. But from the premises this necessarily follows,
(10)
that if we actually supposed that which is not, but is capable of being, to be or to have come to be, there will be nothing impossible in this; but the result
will
be impossible, for the measuring of the diagonal is impossible. For the false and the impossible are
not
the same; that you are standing now is false, but that you should be standing is not impossible.

At the same time it is clear that if, when
A
is real,
B
must be real,
(15)
then, when
A
is possible,
B
also must be possible. For if
B
need not be possible, there is nothing to prevent its not being possible. Now let
A
be supposed possible. Then, when
A
was possible, we agreed that nothing impossible followed if
A
were supposed to be real; and then
B
must of course be real.
(20)
But we supposed
B
to be impossible. Let it be impossible, then. If, then,
B
is impossible,
A
also must be so. But the first
was
supposed impossible; therefore the second also is impossible. If, then,
A
is possible,
B
also will be possible, if they were so related that if
A
is real,
B
must be real. If, then,
A
and
B
being thus related,
¹⁰
B
is not possible on this condition,
¹¹
(25)
A
and
B
will not be related as was supposed.
¹²
And if when
A
is possible,
B
must be possible, then if
A
is real,
B
also must be real. For to say that
B
must be possible, if
A
is possible, means this, that if
A
is real both at the time when and in the way in which it was supposed capable of being real,
B
also must then and in that way be real.
(30)