Today some purported counter-examples to this assertion are given, along with their rebuttals. As far as coming speaking about evil, see paragraph 5 and 6 from the second chapter.
1 Now, it appears that the preceding view may be opposed by certain arguments.
2 Each thing is specified by its own specific difference. But evil is a specific difference in some genera; for instance, among habits and acts in the moral order. Just as virtue is specifically a good habit, so is the contrary vice specifically a bad habit. The same may be said of virtuous and vicious acts. Therefore, evil is that which gives specificity to some things, and thus it is an essence and is natural to certain things.
3 Again, of two contraries, each is a definite nature, for, if one contrary were supposed to be nothing, then it would be either a privation or a pure negation. But good and evil are said to be contraries. Therefore, evil is a nature of some sort.
4 Besides, good and evil are spoken of by Aristotle in the Categories [8: 14a 24] as “genera of contraries.” Now, there is an essence and a definite nature for each kind of genus. There are no species or differences for non-being; so, that which does not exist cannot be a genus. Therefore, evil is a definite essence and nature.
5 Moreover, everything that acts is a real thing. Now, evil does act precisely as evil, for it attacks the good and corrupts it. So, evil precisely as evil is a real thing.
6 Furthermore, wherever the distinction of more or less is found, there must be certain things arranged in hierarchic order, since neither negations nor privations admit of more or less. But among evils, one may be worse than another. It would seem, then, that evil must be a real thing.
7 Again, thing and being are convertible. There is evil in the world. Therefore, it is a real thing and a nature.
1 It is not difficult to answer these arguments. Evil and good are assigned as specific differences in moral matters, as the first argument asserted, because moral matters depend on the will. For this reason, anything that is voluntary belongs in the class of moral matters.
Now, the object of the will is the end and the good. Hence, moral matters get their species from the end, just as natural actions are specified by the form of the active principle; for instance, the act of heating is specified by heat. Hence, because good and evil are so termed by virtue of a universal order, or privation of order, to the end, it is necessary in moral matters for the primary distinction to be between good and evil.
Now, there must be but one primary standard in any one genus. The standard in moral matters is reason. Therefore, it must be from a rational end that things in the moral area are termed good or evil. So, in moral matters, that which is specified by an end that is in accord with reason is called good specifically; and that which is specified by an end contrary to the rational end is termed evil specifically.
Yet that contrary end, even though it runs counter to the rational end, is nevertheless some sort of good: for instance, something that delights on the sense level, or anything like that. Thus, these are goods for certain animals, and even for man, when they are moderated by reason. It also happens that what is evil for one being is good for another. So, evil, as a specific difference in the genus of moral matters, does not imply something that is evil in its own essence, but something that is good in itself, though evil for man, inasmuch as it takes away the order of reason which is the good for man.
2 From this it is also clear that evil and good are contraries according to the way they are understood in the area of moral matters, but they are not when taken without qualification, as the second argument suggested. Rather, in so far as it is evil, evil is the privation of good.
3 In the same way, too, one may understand the statement that evil and good, as found in the moral area, are “genera of contraries”—from which phrase the third argument begins. Indeed, in all moral contraries, either both contraries are evil, as in the case of prodigality and illiberality, or one is good and the other evil, as in the case of liberality and illiberality. Therefore, moral evil is both a genus and a difference, not by the fact that it is a privation of the rational good whence it is termed evil, but by the nature of the action or habit ordered to some end that is opposed to the proper rational end. Thus, a blind man is an individual man, not inasmuch as he is blind but in so far as he is this man. So, also, irrational is an animal difference, not because of the privation of reason but by virtue of a certain kind of nature, to which the absence of reason follows as a consequence.
One can also say that Aristotle calls good and evil genera, not according to his own opinion (for he does not number them among the primary ten genera in which every kind of contrariety is found) but according to the opinion of Pythagoras, who supposed that good and evil are the first genera and first principles, and who placed ten prime contraries under each of them: under the good were, “limit, even, one, right, male, rest, straight, light, square, and finally good”; and under evil were, “the unlimited, odd, multitude, left, female, motion, curved, darkness, oblong, and finally evil [cf. Met. I, 5: 986a 24-27]. Thus, here and in several places in the treatises on logic, he uses examples in accord with the views of other philosophers, as if they were more acceptable in his time.
In fact, this statement has some truth, since it is impossible for a probable statement to be entirely false. In the case of all contraries, one is perfect and the other is a diminished perfection, having, as it were, some privation mixed with it. For instance, white and hot are perfect conditions, but cold and black are imperfect, connoting something of privation. Therefore, since every diminution and privation pertains to the formal character of evil, and every perfection and fulfillment to the formal character of good, it appears to be always so between contraries, that one is included under the good and the other approaches the notion of evil. From this point of view, good and evil seem to be genera of all contraries.
Notes Uncertainty fans and probabalists take note: “it is impossible for a probable statement to be entirely false.” It were entirely false, it would be false and not probable; and the opposite is so, too.
4 In this way it also becomes apparent how evil is opposed to the good, which is the starting point of the fourth argument. According as there is added a privation of a contrary form, and a contrary end, to a form and an end (which have the rational character of good and are true principles of action) the action that results from such a form and end is attributed to the privation and the evil.
Yet, this attribution is accidental, for privation, as such, is not the principle of any action. Hence, Dionysius says, quite properly, in the fourth chapter of On the Divine Names, that “evil does not fight against good, except through the power of the good; in itself, indeed, it is powerless and weak,” the principle of no action, as it were. However, we say that evil corrupts the good, not only when it acts in virtue of the good, as has been explained, but also formally of itself. Thus, blindness is said to corrupt sight, for it is itself the corruption of sight; similarly, whiteness is said to color a wall, when it is the actual color of the wall.
5 We do indeed say that something is more or less evil than another thing, in reference to the good that it lacks. Thus, things which imply a privation admit of increase or decrease in degree, as do the unequal and the dissimilar. For we say that something is more unequal when it is more removed from equality and, likewise, that something is more dissimilar when it is farther away from similitude. Consequently, a thing that is more deprived of goodness is said to be more evil, as it were, more distant from the good. However, privations do not increase as do things that have an essence, such as qualities and forms, as the fifth argument assumes, but through increase of the depriving cause. Thus, just as the air is darker when more obstacles have been placed before the light, so does a thing become farther removed from participation in the light.
6 We also say that evil is in the world, not as possessing some essence, nor as a definitely existing thing, as the sixth argument suggested, but for the same reason that we may call something evil by virtue of its evil. For instance, blindness, or any other sort of privation, is said to exist because an animal is blinded by its blindness. Indeed, there are two ways of talking about being, as the Philosopher teaches in his Metaphysics [IV, 7: 1017a 8].
In one way, being means the essence of a thing, and thus it falls into the ten categories; so taken, no privation can be called a being. In another way, being means the truth in a judgment; in this meaning, privation is called a being, inasmuch as something is said to be deprived by virtue of a privation.