Again, see whether he has placed the differentia inside the species, by taking (e.g.) immortal to be essentially a god. For the result will be that the species has an equal or wider denotation; for always the differentia has an equal or a wider [123a1] denotation than the species. Moreover, see whether he has placed the genus inside the differentia, by making colour (e.g.) to be essentially dispersive, or number essentially odd. Also, see if he has mentioned the genus as differentia; for it is possible for a man to bring forward a thesis of this kind as well, e.g. that mixture is a [5] differentia of fusion, or that change of place is a differentia of locomotion. All such cases should be examined by means of the same principles; for they depend upon common rules; for the genus should have a wider denotation than its differentia, and also should not partake of its differentia; whereas, if it is given in this manner, neither of the aforesaid requirements can be satisfied; for the genus will both have a [10] narrower denotation than its differentia, and will partake of it.
Again, if no differentia belonging to the genus is predicated of the given species, neither will the genus be predicated of it; e.g. of soul neither odd nor even is predicated; neither therefore is number. Moreover, see whether the species is naturally prior and abolishes the genus along with itself; for the contrary seems to [15] be the case. Moreover, if it is possible for the genus stated, or for its differentia, to be absent, e.g. for movement to be absent from the soul, or truth and falsehood from opinion, then neither of the terms stated can be its genus or its differentia; for it seems that the genus and the differentia accompany the species, as long as it exists.
[20] 3 · Look and see, also, if what is placed in the genus partakes or could partake of any contrary of the genus; for in that case the same thing will at the same time partake of contrary things, seeing that the genus is never absent from it, while it partakes, or can partake, of the contrary as well. Moreover, see whether the species shares in any character which it is utterly impossible for any member of the [25] genus to have. Thus (e.g.) if the soul has a share in life, while it is impossible for any number to live, then the soul will not be a species of number.
You should look and see, also, if the species is a homonym of the genus, and employ as your elementary principles those already stated for dealing with homonyms;12 for the genus and the species are synonymous.
Seeing that of every genus there is more than one species, look and see if it is [30] impossible that there should be another species belonging to the genus stated, for if there is none, then clearly what has been stated will not be a genus at all.
Look and see, also, if he has given as genus something spoken of metaphorically, describing (e.g.) temperance as a harmony; for a genus is always predicated of its species in its literal sense, whereas harmony is predicated of temperance not in a [35] literal sense but metaphorically; for a harmony always consists in notes.
Moreover, if there is any contrary of the species, examine it. The examination [123b1] may take different forms; first of all see if the contrary as well is found in the same genus, supposing the genus to have no contrary; for contraries ought to be found in the same genus, if there is no contrary to the genus. Supposing, on the other hand, that there is a contrary to the genus, see if the contrary of the species is found in the [5] contrary genus; for of necessity the contrary must be in the contrary, if there is any contrary to the genus. Each of these points is made plain by means of induction. Again, see whether the contrary of the species is not found in any genus at all, but is itself a genus, e.g. the good; for if this is not found in any genus, neither will its contrary be found in any genus, but will itself be a genus, as happens in the case of [10] good and evil; for neither of these is found in a genus, but each of them is a genus. Moreover, see if both genus and species are contrary to something, and one pair of contraries has an intermediary, but not the other. For if the genera have an intermediary, so should their species as well, and if the species have, so should their [15] genera as well, as is the case with virtue and vice, and with justice and injustice; for each pair has an intermediary. (An objection to this is that there is no intermediary between health and disease, although there is one between evil and good.) Or see whether, though there is an intermediary between both, i.e. both between the species and between the genera, yet it is not similarly related, but in one case negatively, but in the other case as a subject. For it is a reputable opinion that the [20] relation should be similar in both cases, as it is in the cases of virtue and vice and of justice and injustice; for the intermediaries between both are purely negative. Moreover, whenever the genus has no contrary, look and see not merely whether the contrary is found in the same genus, but the intermediate as well; for the genus containing the extremes contains the intermediates as well, as (e.g.) in the case of [25] white and black; for colour is the genus both of these and of all the intermediate colours. (An objection may be raised that defect and excess are found in the same genus (for both are in the genus evil), whereas moderate amount, an intermediate between them, is found not in evil but in good.) Look and see also whether, while the genus has a contrary, the species has none; for if the genus is contrary to anything, [30] so too is the species, as virtue and vice, and justice and injustice. Likewise, also, if one were to look at other instances, one would come to see this clearly. (An objection may be raised in the case of health and disease; for health without qualification is [35] the contrary of disease, whereas a particular disease, e.g. fever and ophthalmia and any other particular disease, has no contrary.)
[124a1] If, therefore, you are demolishing a view, there are all these ways in which you should make your examination; for if the aforesaid characters do not belong to it, clearly what has been given is not the genus. If, on the other hand, you are establishing a view, there are three ways: in the first place, see whether the contrary is found in the genus stated, supposing the genus to have no contrary; for if the [5] contrary is found in it, clearly the species in question is found in it as well. Moreover, see if the intermediate species is found in the genus stated; for whatever genus contains the intermediate contains the extremes as well. Again, if the genus has a contrary, look and see whether the contrary species is found in the contrary genus; for if so, clearly also the species in question is found in the genus in question.
[10] Again, consider in the case of the inflexions and the co-ordinates, and see whether they follow in the same way, both in demolishing and in establishing a view. For whatever attribute belongs or does not belong to one belongs or does not belong at the same time to all; e.g. if justice is a particular form of knowledge, then also justly is knowingly and the just man is a man of knowledge; whereas if any of these things is not so, then neither is any of the rest of them.
[15] 4 · Again, consider the case of things that bear a like relation to one another. Thus (e.g.) the relation of the pleasant to pleasure is like that of the useful to the good; for in each case the one produces the other. If therefore pleasure is essentially good, then also the pleasant will be essentially useful; for clearly it will be productive of good, seeing that pleasure is good. In the same way also consider the [20] processes of generation and destruction; if (e.g.) to build is to be active, then to have built is to have been active, and if to learn is to recollect, then also to have learnt is to have recollected, and if to be decomposed is to be destroyed, then to have been decomposed is to have been destroyed, and decomposition is a kind of destruction. Consider also in the same way the case of things that generate or destroy, and of the [25] capacities and uses of things; and in general, both in demolishing and in establishing, you should examine things in the light of any resemblance of whatever description, as we were saying in the case of generation and destruction. For if what tends to destroy tends to decompose, then also to be destroyed is to be decomposed; [30] and if what tends to generate tends to produce, then to be generated is to be produced, and generation is production. Likewise, also, in the case of the capacities and uses of things; for if a ca
pacity is a disposition, then also to be capable is to be disposed, and if the use of anything is an activity, then to use it is to be active, and to have used it is to have been active.
[35] If the opposite of the species is a privation, there are two ways of demolishing an argument. First of all by looking to see if the opposite is found in the given genus; for either the privation is never absolutely in the same genus, or at least not in the same ultimate genus: e.g. if the ultimate genus containing sight is perception, then blindness will not be a perception. Secondly, if there is a privation opposed to both genus and species, but the opposite of the species is not found in the opposite of the [124b1] genus, then neither will the given species be in the given genus. If, then, you are demolishing a view, you should follow the rule as stated; but if establishing one there is but one way; for if the opposite species is found in the opposite genus, then also the species in question will be found in the genus in question: e.g. if blindness is [5] a form of lack of perception, then sight is a form of perception.
Again, look at the negations in reverse order, according to the method described in the case of accident:13 e.g. if the pleasant is essentially good, what is not good is not pleasant. [For were this not so, something not good would then be pleasant.]14 For it is impossible, if good is the genus of pleasant, that anything not [10] good should be pleasant; for of things of which the genus is not predicated, none of the species is predicated either. Also, in establishing a view, you should adopt the same method of examination; for if what is not good is not pleasant, then what is pleasant is good, so that good is the genus of pleasant.
If the species is a relative, see whether the genus is a relative as well; for if the [15] species is a relative, so too is the genus, as is the case with double and multiple; for each is a relative. If, on the other hand, the genus is a relative, there is no necessity that the species should be so as well; for knowledge is a relative, but not so grammar. (Or possibly not even the first statement would seem true; for virtue is essentially [25] noble and essentially good, and yet, while virtue is a relative, good and noble are not relatives but qualities.)
Again, see whether the species fails to be related to the same thing in its own right, and in respect of its genus: e.g. if double is the double of a half, then it ought also to be multiple of a half. Otherwise multiple will not be the genus of double.[25]
Moreover, see whether it fails to be related to the same thing both in respect of its genus and in respect of all the genera of its genus. For if the double is a multiple of a half, then it will also be in excess of a half; and, in general, in respect of all the [30] higher genera it will be related to a half. (An objection may be raised that there is no necessity for a term to be related to the same thing in its own right and in respect of its genus; for knowledge is called knowledge of an object of knowledge, whereas it is called a state and disposition not of an object of knowledge but of the soul.)
Again, see whether the genus and the species are used in the same way in [35] respect of the inflexions they take, e.g. datives and genitives and all the rest.15 For as the species is used, so should the genus be as well, as in the case of double and its higher genera; for both double and multiple take a genitive. Likewise, also, in the case of knowledge; for both knowledge itself and its genera, e.g. disposition and state, take a genitive. (An objection may be raised that in some cases it is not so; for [125a1] different and contrary take a dative, whereas other, which is the genus of these terms, takes a genitive—for we talk of being other than something.)
[5] Again, see whether terms used in like manner in respect of inflexions fail to yield a like construction when converted, as do double and multiple. For each of these terms takes a genitive both in itself and in its converted form; for both a half and a fraction take the genitive. The case is the same also as regards both [10] knowledge and belief; for they take a genitive themselves, and likewise after conversion; for object of knowledge and object of belief both take a dative. If, then, in any cases the constructions after conversion are not alike, clearly the one term is not the genus of the other.
Again, see whether the species and the genus fail to be used in relation to an [15] equal number of things; for it seems that the uses of both are alike and equal in number, as is the case with transfers and gifts. For a transfer is of something and to someone, and also a gift is of something and to someone; and transfer is the genus of gift, for a gift is a transfer that need not be returned. In some cases, however, it turns out that they are not related to an equal number of things; for while double is [20] double of something, in excess and greater are in something, as well as of something; for what is in excess or greater is always in excess in something, as well as in excess of something.16 Hence the terms in question are not the genera of double, inasmuch as they are not used in relation to an equal number of things with the species. Or perhaps it is not universally true that species and genus are used in relation to an equal number of things.
[25] See, also, if the opposite of the species has the opposite of the genus as its genus, e.g. whether, if multiple is the genus of double, fraction is of half. For the opposite of the genus should always be the genus of the opposite. If, then, anyone were to assert that knowledge is essentially perception, then also the object of knowledge will have to be essentially an object of perception, whereas it is not; for an object of knowledge is not always an object of perception; for objects of [30] knowledge include some of the objects of the intellect as well. Hence object of perception is not the genus of object of knowledge; and if it is not, neither is perception the genus of knowledge.
Seeing that of relatives some are of necessity found in, or about, the things in relation to which they happen at any time to be used (e.g. composition and state and [35] balance; for in nothing else can the aforesaid terms possibly be found except in the things in relation to which they are used), while others need not be found in the things in relation to which they are used at any time, though they still may be (e.g. if the soul is an object of knowledge, for it is quite possible that the soul should possess knowledge of itself, but it is not necessary—for knowledge may just as well be found [125b1] in something different), while for others, again, it is absolutely impossible that they should be found in the things in relation to which they happen at any time to be used (as e.g. that a contrary should be found in its contrary or knowledge in the object of knowledge unless the object of knowledge happens to be a soul or a man)—you [5] should look, therefore, and see whether he places a term of one kind inside a genus that is not of that kind, e.g. suppose he has said that memory is a persisting of knowledge. For a persisting is always found in that which persists, and is about it, so that the persisting of knowledge also will be found in knowledge. Memory, then, is found in knowledge, seeing that it is a persisting of knowledge. But this is impossible; for memory is always found in the soul. The aforesaid commonplace [10] rule is common to the subject of accident as well; for it makes no difference whether you say that persisting is the genus of memory, or allege that it is an accident of it. For if in any way whatever memory is a persisting of knowledge, the same argument in regard to it will apply.
5 · Again, see if he has placed what is a state inside the genus activity, or an [15] activity inside the genus state, e.g. by calling perception a movement communicated through the body; for perception is a state, whereas movement is an activity. Likewise, also, if he has said that memory is a state that is retentive of a belief; for memory is never a state, but rather an activity.
They also make a mistake who rank a state within the capacity that attends it, [20] e.g. by calling good temper mastery of anger, and courage and justice mastery of fears and of gains; for courage and good temper belong to the man who is immune from passion, whereas mastery is exhibited by the man who is exposed to passion and not led by it. Quite possibly, indeed, each of the former is attended by a capacity such that, if he were exposed to passion, he would control it and not be led [25] by it; but, fo
r all that, this is not what is meant by being courageous in the one case, and good-tempered in the other; what is meant is an absolute immunity from any passions of that kind at all.
Sometimes, also, people state any kind of attendant feature as the genus, e.g. pain as the genus of anger and belief as that of conviction. For both of the things in [30] question follow in a certain sense upon the given species, but neither of them is genus to it. For when the angry man feels pain, the pain has appeared in him earlier than the anger; for his anger is not the cause of his pain, but his pain of his anger, so that anger simply is not pain. By the same reasoning, neither is conviction belief; for it is possible to have the same belief even without being convinced of it, whereas this [35] is impossible if conviction is a species of belief; for it is impossible for a thing still to remain the same if it is entirely transferred out of its species, just as the same animal could not at one time be, and at another not be, a man. If, on the other hand, anyone says that a man who has a belief must of necessity be also convinced of it, then belief and conviction will be used with an equal denotation, so that not even so [126a1] could the former be the genus of the latter—for the denotation of the genus should be wider.
The Complete Works of Aristotle Page 37
