by Aristotle
See, also, whether both naturally come to be in the same thing; for what contains the species contains the genus as well: e.g. what contains white contains colour as well, and what contains knowledge of grammar contains knowledge as [5] well. If, therefore, any one says that shame is fear, or that anger is pain, the result will be that genus and species are not found in the same thing; for shame is found in the reasoning faculty, whereas fear is in the spirited faculty; and pain is found in the [10] faculty of desire (for in this pleasure also is found), whereas anger is found in the spirited faculty. Hence the terms given are not the genera, seeing that they do not naturally come to be in the same thing as the species. Likewise, also, if friendship is found in the faculty of desire, it is not a form of wishing; for wishing is always found in the reasoning faculty. This commonplace rule is useful also in dealing with accident; for the accident and that of which it is an accident are both found in the [15] same thing, so that if they do not appear in the same thing, clearly it is not an accident.
Again, see if the species partakes of the alleged genus only in some particular respect; for it seems that the genus is not partaken in only in some particular respect; for a man is not an animal in a particular respect, nor is grammar [20] knowledge. Likewise also in other instances. Look, therefore, and see if in certain cases the genus is partaken in only in a certain respect; e.g. if animal has been described as essentially an object of perception or of sight. For an animal is an object of perception or of sight in a particular respect only; for it is in respect of its body that it is perceived and seen, not in respect of its soul; so that object of sight [25] and object of perception will not be the genus of animal.
Sometimes also people unawares place the whole inside the part, calling (e.g) animal an animate body; whereas the part is not predicated in any sense of the whole, so that body could not be the genus of animal, seeing that it is a part.
[30] See also if he has put anything that is blameworthy or objectionable into capacity or the capable, e.g. by calling a sophist or a slanderer or a thief one who is capable of secretly thieving other people’s property. For none of the aforesaid characters is so called because he is capable in one of these respects; for even God [35] and the good man are capable of doing bad things, but that is not their character; for it is always in respect of their choice that bad men are so called. Moreover, a capacity is always a desirable thing; for even the capacities for doing bad things are desirable, and that is why we say that even God and the good man possess them; for [126b1] they are capable (we say) of doing evil. So then capacity can never be the genus of anything blameworthy. Otherwise, the result will be that some blameworthy thing is desirable; for there will be a capacity that is blameworthy.
Also, see if he has put anything that is precious or desirable for its own sake [5] into capacity or the capable or the productive. For capacity, and what is capable or productive of anything, is always desirable for the sake of something else.
Or see if he has put anything that is in two genera or more into one of them only. For some things it is impossible to place in a single genus, e.g. the cheat and the slanderer; for neither he who has the intention without the capacity, nor he who [10] has the capacity without the intention, is a slanderer or cheat, but he who has both of them. Hence he must be put not into one genus, but into both the aforesaid genera.
Moreover, people sometimes give things the wrong way about, genus as differentia, and differentia as genus, calling (e.g.) astonishment an excess of [15] wonderment and conviction strength of belief. For neither excess nor strength is the genus, but the differentia; for astonishment seems to be an excessive wonderment, and conviction to be a strong belief, [so that wonderment and belief are the genus, while excess and strength are the differentia.]17 Moreover, if any one gives excess and strength as genera, then inanimate things will be convinced and astonished. For [20] the strength and excess of a thing are found in that thing of which they are. If, therefore, astonishment is an excess of wonderment the astonishment will be found in the wonderment, so that wonderment will be astonished. Likewise, also, conviction will be found in belief, if it is strength of belief, so that the belief will be [25] convinced. Moreover, a man who argues in this style will in consequence find himself calling strength strong and excess excessive; for there is such a thing as a strong conviction; if then conviction is strength there will be a strong strength. [30] Likewise, also, there is such a thing as excessive astonishment; if then astonishment is an excess, there will be an excessive excess. But neither of these things seems to be the case any more than that knowledge is an object of knowledge or motion a moving thing.
Sometimes, too, people make the mistake of putting an affection into that [35] which is affected, as its genus, e.g. those who say that immortality is everlasting life; for immortality seems to be a certain affection or accidental feature of life. That this is true would appear clear if anyone were to admit that a man can pass from being mortal and become immortal; for no one will assert that he takes another life, but that a certain accidental feature or affection enters into this one as it is. So then [127a1] life is not the genus of immortality.
Again, see if they say that an affection is that of which it is an affection, calling (e.g.) wind air in motion; [Rather, wind is a movement of air]18 for the same air [5] persists both when it is in motion and when it is still. Hence wind is not air at all; for then there would also have been wind when the air was not in motion, seeing that the same air which formed the wind persists. Likewise, also, in other cases of the kind. Even, then, if we ought in this instance to admit that wind is air in motion, yet we [10] should not accept this sort of thing in all those things of which the genus is not true, but only in cases where the given genus is truly predicated. For in some cases, e.g. mud or snow, it does not seem to be true. For people say that snow is frozen water and mud is earth mixed with moisture, whereas snow is not water, nor mud earth, so [15] that neither of the given terms could be the genus; for the genus should be true of all its species. Likewise neither is wine fermented water, as Empedocles speaks of ‘water fermented in wood’19—for it simply is not water at all.
6 · Moreover, see whether the given term fails to be the genus of anything at [20] all; for then clearly it also fails to be the genus of the species mentioned. Examine the point by seeing whether the objects that partake of the genus fail to be specifically different from one another, e.g. white objects; for these do not differ specifically from one another, whereas of a genus the species are always different, so that white will not be the genus of anything. [25]
Again, see whether he has named as genus or differentia some feature that goes with everything; for there are several attributes that follow everything: thus (e.g.) being and one are among the attributes that follow everything. If, therefore, he has rendered being as a genus, clearly it will be the genus of everything, seeing [30] that it is predicated of everything; for the genus is never predicated of anything except of its species. Hence one will be a species of being. The result, therefore, is that of all things of which the genus is predicated, the species is predicated as well, seeing that being and one are predicates of absolutely everything, whereas the predication of the species ought to be of narrower range. If, on the other hand, he [35] has named as differentia some attribute that follows everything, clearly the denotation of the differentia will be equal to, or wider than, that of the genus. For if the genus, too, is an attribute that follows everything, the denotation of the differentia will be equal to its denotation, while if the genus does not follow everything, it will be wider.
[127b1] Moreover, see if the given genus is said to be in the species as subject, as white in the case of snow, thus showing clearly that it will not be the genus; for the genus is only said of the species as subject.
[5] Look and see also if the genus fails to be synonymous with its species. For the genus is always predicated of its species synonymously.
Moreover, beware, whenever both species an
d genus have a contrary, and he places the better of the contraries inside the worse genus; for the result will be that [10] the remaining species will be found in the remaining genus, seeing that contraries are found in contrary genera, so that the better species will be found in the worse genus and the worse in the better; but it seems that of the better species the genus too is better. Also see if he has placed something inside the worse and not inside the better genus, when it is related in like manner to both, as (e.g.) if he has called the [15] soul essentially a form of motion or a moving thing. For the same soul seems to be a principle alike of rest and of motion, so that, if rest is the better of the two, this is the genus into which the soul should have been put.
Moreover, judge by means of greater and less degrees: if overthrowing a view, see whether the genus admits of a greater degree, whereas neither the species itself [20] nor anything that is called after it does so; e.g. if virtue admits of a greater degree, so too does justice and the just man; for one man is called more just than another. If, therefore, the given genus admits of a greater degree, whereas neither the species itself nor anything called after it does so, then what has been given will not be the [25] genus.
Again, if what is more generally, or as generally, thought to be the genus is not so, clearly neither is the given genus. The commonplace rule in question is useful especially in cases where the species appears to have several predicates in what it is, and where it has not been determined and we cannot say which of them is genus; e.g. [30] both pain and belief seem to be predicated of anger in what it is; for the angry man is both in pain and also believes that he is slighted. The same mode of inquiry may be applied also to the case of the species, by comparing it with some other species; for if the one which is more generally, or as generally, thought to be found in the [35] given genus is not found herein, then clearly neither will the given species be found therein.
In demolishing a view, therefore, you should follow the rule as stated. In establishing one, on the other hand, the commonplace rule that you should see if both the given genus and the species admit of a greater degree will not serve; for [128a1] even though both admit it, it is still possible for one not to be the genus of the other. For both beautiful and white admit of a greater degree, and neither is the genus of the other. On the other hand, the comparison of the genera and of the species one with another is of use: e.g. supposing this and that to have a like claim to be genus, [5] then if one is a genus, so also is the other. Likewise also, if what has less claim is a genus, so also is what has more claim: e.g. if capacity has more claim than virtue to be a genus of self-control, and virtue is a genus, so also is capacity. The same observations will apply also in the case of the species. For instance, supposing this and that to have a like claim to be a species of the genus in question, then if the one [10] is a species, so also is the other; and if that which is less generally thought to be so is a species, so also is that which is more generally thought to be so.
Moreover, to establish a view, you should look and see if the genus is predicated in what it is of those things to which it has been ascribed as genus, supposing there to have been given not one single species but several different ones; [15] for then clearly it will be the genus. If, on the other hand, a single species has been given, look and see whether the genus is predicated of the other species as well; for then, again, the result will be that it is predicated of several different species.
Since some people think that the differentia, too, is a predicate of the various [20] species in what it is, you should distinguish the genus from the differentia by employing the aforesaid elementary principles—first, that the genus has a wider denotation than the differentia; then, that in giving what a thing is it is more fitting to state the genus than the differentia, for anyone who says that man is an animal [25] shows what man is better than he who describes him as terrestrial; also that the differentia always signifies a quality of the genus, whereas the genus does not do this of the differentia; for he who says terrestrial describes an animal of a certain quality, whereas he who says animal does not describe a terrestrial thing of a certain quality.
The differentia, then, should be distinguished from the genus in this manner. [30] Now since it seems that if what is musical, in being musical, possesses knowledge in some respect, then also music is a particular kind of knowledge; and also that if what walks is moved in walking, then walking is a particular kind of movement; you should therefore examine in the aforesaid manner any genus in which you want to establish the presence of something: e.g., if you wish to prove that knowledge is [35] essentially conviction, see whether the knower in knowing is convinced; for then clearly knowledge will be a particular kind of conviction. You should proceed in the same way also in regard to the other cases of this kind.
Moreover, seeing that it is difficult to distinguish whatever always follows along with a thing, and is not convertible with it, from its genus, if this follows that universally, whereas that does not follow this universally—as e.g. calm always [128b1] follows windlessness and divisible follows number, but not conversely (for the divisible is not always a number, nor windlessness calm)—you may yourself argue as though the one which always follows is the genus, whenever the other is not convertible with it; if, on the other hand, some one else puts forward the proposition, [5] do not accept it universally. An objection to it is that not-being always follows what is coming to be (for what is coming to be is not) and is not convertible with it (for what is not is not always coming to be), but nevertheless not-being is not the genus [10] of coming to be; for not-being has not any species at all.
Questions, then, in regard to genus should be investigated in the ways described.
BOOK V
1 · The question whether the attribute stated is or is not a property, should [15] be examined by the following methods. A property is given either in its own right and for always or relative to something else and for a time: e.g. it is property in its own right of man to be by nature a civilized animal; a relative property is one like that of the soul in relation to the body, viz. that the one is fitted to command, and the other to obey; a property that always holds is one like the property which belongs to God, of being an immortal living being; a property that holds for a time is [20] one like the property which belongs to any particular man of walking in the gymnasium.
When a property is given relatively to something else, there are either two problems or four. For if you ascribe this same property to one thing and deny it of another, only two problems arise, as in the case of a statement that it is a property of [25] a man, in relation to a horse, to be a biped. For one might try both to show that a man is not a biped, and also that a horse is a biped: in both ways the property would be upset. If on the other hand you ascribe one of two attributes to each of two things, and deny it in each case of the other, there will then be four problems; as in the case of a statement that it is a property of a man in relation to a horse for the former to be [30] a biped and the latter a quadruped. For then it is possible to try to show both that a man is not naturally a biped, and that he is a quadruped, and also that the horse is a biped, and that it is not a quadruped. If you prove any of these at all, the intended attribute is demolished.20
A property in its own right is one which is ascribed to a thing in comparison with everything else and distinguishes it from everything else, as does being a [35] mortal living being capable of receiving knowledge in the case of man. A property relative to something else is one which separates its subject off not from everything else but only from a particular definite thing, as does the property which virtue possesses, relative to knowledge, viz. that the former is naturally produced in more than one faculty, whereas the latter is produced in that of reason alone, and in those who have a reasoning faculty. A property for always is one which is true at every [129a1] time, and never fails, like being compounded of soul and body, in the case of a living creature. A property for a time is one which is true at some particular
time, and does not of necessity always follow; as, of some particular man, that he walks in the [5] market-place.
To ascribe a property relatively to something else means to state the difference between them as it is found either universally and always, or for the most part and in most cases: thus a difference that is found universally and always, is one such as man possesses relatively to a horse, viz. being a biped; for a man is always and in every case a biped, whereas no horse is ever a biped. On the other hand, a difference [10] that is found for the most part and in most cases, is one such as the faculty of reason possesses relative to that of desire and spirit, in that the former commands, while the latter obeys; for the reasoning faculty does not always command, but sometimes also is under command, nor is that of desire and spirit always under command, but [15] also on occasion assumes the command, whenever the man’s soul is vicious.
Of properties the most general are those which hold in their own right and always and the relative. For a relative property gives rise, as we said before, to several problems; for of necessity the problems arising are either two or four, so that [20] arguments in regard to these are several. A property in its own right and one for always you can discuss in relation to many things, or can observe in relation to many periods of time: if in its own right, discuss it in relation to many things; for the property ought to belong to its subject relatively to every single thing that there is, so that if the subject is not distinguished relatively to everything else, the property will not have been given correctly. A permanent property you should observe in [25] relation to many periods of time; for if it does not or did not, or is not going to, belong, it will not be a property. On the other hand, about a temporary property we do not inquire further than in regard to the present; and so arguments in regard to it are not many; whereas a general problem is one in regard to which it is possible for [30] arguments both numerous and good to arise.