Various Works

  clearly follows that the species must be in two non-subaltern

  genera. Or perhaps it is not impossible for the same differentia to be

  used of two non-subaltern genera, and we ought to add the words

  'except they both be subordinate members of the same genus'. Thus

  'walking animal' and 'flying animal' are non-subaltern genera, and

  'biped' is the differentia of both. The words 'except they both be

  subordinate members of the same genus' ought therefore to be added;

  for both these are subordinate to 'animal'. From this possibility,

  that the same differentia may be used of two non-subaltern genera,

  it is clear also that there is no necessity for the differentia to

  carry with it the whole of the genus to which it belongs, but only the

  one or the other of its limbs together with the genera that are higher

  than this, as 'biped' carries with it either 'flying' or 'walking

  animal'.

  See, too, if he has rendered 'existence in' something as the

  differentia of a thing's essence: for the general view is that

  locality cannot differentiate between one essence and another.

  Hence, too, people condemn those who divide animals by means of the

  terms 'walking' and 'aquatic', on the ground that 'walking' and

  'aquatic' indicate mere locality. Or possibly in this case the censure

  is undeserved; for 'aquatic' does not mean 'in' anything; nor does

  it denote a locality, but a certain quality: for even if the thing

  be on the dry land, still it is aquatic: and likewise a land-animal,

  even though it be in the water, will still be a and not an

  aquatic-animal. But all the same, if ever the differentia does

  denote existence in something, clearly he will have made a bad

  mistake.

  Again, see if he has rendered an affection as the differentia: for

  every affection, if intensified, subverts the essence of the thing,

  while the differentia is not of that kind: for the differentia is

  generally considered rather to preserve that which it

  differentiates; and it is absolutely impossible for a thing to exist

  without its own special differentia: for if there be no 'walking',

  there will be no 'man'. In fact, we may lay down absolutely that a

  thing cannot have as its differentia anything in respect of which it

  is subject to alteration: for all things of that kind, if intensified,

  destroy its essence. If, then, a man has rendered any differentia of

  this kind, he has made a mistake: for we undergo absolutely no

  alteration in respect of our differentiae.

  Again, see if he has failed to render the differentia of a

  relative term relatively to something else; for the differentiae of

  relative terms are themselves relative, as in the case also of

  knowledge. This is classed as speculative, practical and productive;

  and each of these denotes a relation: for it speculates upon

  something, and produces something and does something.

  Look and see also if the definer renders each relative term

  relatively to its natural purpose: for while in some cases the

  particular relative term can be used in relation to its natural

  purpose only and to nothing else, some can be used in relation to

  something else as well. Thus sight can only be used for seeing, but

  a strigil can also be used to dip up water. Still, if any one were

  to define a strigil as an instrument for dipping water, he has made

  a mistake: for that is not its natural function. The definition of a

  thing's natural function is 'that for which it would be used by the

  prudent man, acting as such, and by the science that deals specially

  with that thing'.

  Or see if, whenever a term happens to be used in a number of

  relations, he has failed to introduce it in its primary relation: e.g.

  by defining 'wisdom' as the virtue of 'man' or of the 'soul,' rather

  than of the 'reasoning faculty': for 'wisdom' is the virtue

  primarily of the reasoning faculty: for it is in virtue of this that

  both the man and his soul are said to be wise.

  Moreover, if the thing of which the term defined has been stated

  to be an affection or disposition, or whatever it may be, be unable to

  admit it, the definer has made a mistake. For every disposition and

  every affection is formed naturally in that of which it is an

  affection or disposition, as knowledge, too, is formed in the soul,

  being a disposition of soul. Sometimes, however, people make bad

  mistakes in matters of this sort, e.g. all those who say that

  'sleep' is a 'failure of sensation', or that 'perplexity' is a state

  of 'equality between contrary reasonings', or that 'pain' is a

  'violent disruption of parts that are naturally conjoined'. For

  sleep is not an attribute of sensation, whereas it ought to be, if

  it is a failure of sensation. Likewise, perplexity is not an attribute

  of opposite reasonings, nor pain of parts naturally conjoined: for

  then inanimate things will be in pain, since pain will be present in

  them. Similar in character, too, is the definition of 'health', say,

  as a 'balance of hot and cold elements': for then health will be

  necessarily exhibited by the hot and cold elements: for balance of

  anything is an attribute inherent in those things of which it is the

  balance, so that health would be an attribute of them. Moreover,

  people who define in this way put effect for cause, or cause for

  effect. For the disruption of parts naturally conjoined is not pain,

  but only a cause of pain: nor again is a failure of sensation sleep,

  but the one is the cause of the other: for either we go to sleep

  because sensation fails, or sensation fails because we go to sleep.

  Likewise also an equality between contrary reasonings would be

  generally considered to be a cause of perplexity: for it is when we

  reflect on both sides of a question and find everything alike to be in

  keeping with either course that we are perplexed which of the two we

  are to do.

  Moreover, with regard to all periods of time look and see whether

  there be any discrepancy between the differentia and the thing

  defined: e.g. supposing the 'immortal' to be defined as a 'living

  thing immune at present from destruction'. For a living thing that

  is immune 'at present' from destruction will be immortal 'at present'.

  Possibly, indeed, in this case this result does not follow, owing to

  the ambiguity of the words 'immune at present from destruction': for

  it may mean either that the thing has not been destroyed at present,

  or that it cannot be destroyed at present, or that at present it is

  such that it never can be destroyed. Whenever, then, we say that a

  living thing is at present immune from destruction, we mean that it is

  at present a living thing of such a kind as never to be destroyed: and

  this is equivalent to saying that it is immortal, so that it is not

  meant that it is immortal only at present. Still, if ever it does

  happen that what has been rendered according to the definition belongs

  in the present only or past, whereas what is meant by the word does

  not so belong, then the two could not be the same. So, then, this

  commonplace ru
le ought to be followed, as we have said.

  7

  You should look and see also whether the term being defined is

  applied in consideration of something other than the definition

  rendered. Suppose (e.g.) a definition of 'justice' as the 'ability

  to distribute what is equal'. This would not be right, for 'just'

  describes rather the man who chooses, than the man who is able to

  distribute what is equal: so that justice could not be an ability to

  distribute what is equal: for then also the most just man would be the

  man with the most ability to distribute what is equal.

  Moreover, see if the thing admits of degrees, whereas what is

  rendered according to the definition does not, or, vice versa, what is

  rendered according to the definition admits of degrees while the thing

  does not. For either both must admit them or else neither, if indeed

  what is rendered according to the definition is the same as the thing.

  Moreover, see if, while both of them admit of degrees, they yet do not

  both become greater together: e.g. suppose sexual love to be the

  desire for intercourse: for he who is more intensely in love has not a

  more intense desire for intercourse, so that both do not become

  intensified at once: they certainly should, however, had they been the

  same thing.

  Moreover, suppose two things to be before you, see if the term to be

  defined applies more particularly to the one to which the content of

  the definition is less applicable. Take, for instance, the

  definition of 'fire' as the 'body that consists of the most rarefied

  particles'. For 'fire' denotes flame rather than light, but flame is

  less the body that consists of the most rarefied particles than is

  light: whereas both ought to be more applicable to the same thing,

  if they had been the same. Again, see if the one expression applies

  alike to both the objects before you, while the other does not apply

  to both alike, but more particularly to one of them.

  Moreover, see if he renders the definition relative to two things

  taken separately: thus, the beautiful' is 'what is pleasant to the

  eyes or to the ears": or 'the real' is 'what is capable of being acted

  upon or of acting'. For then the same thing will be both beautiful and

  not beautiful, and likewise will be both real and not real. For

  'pleasant to the ears' will be the same as 'beautiful', so that 'not

  pleasant to the ears' will be the same as 'not beautiful': for of

  identical things the opposites, too, are identical, and the opposite

  of 'beautiful' is 'not beautiful', while of 'pleasant to the ears' the

  opposite is not pleasant to the cars': clearly, then, 'not pleasant to

  the ears' is the same thing as 'not beautiful'. If, therefore,

  something be pleasant to the eyes but not to the ears, it will be both

  beautiful and not beautiful. In like manner we shall show also that

  the same thing is both real and unreal.

  Moreover, of both genera and differentiae and all the other terms

  rendered in definitions you should frame definitions in lieu of the

  terms, and then see if there be any discrepancy between them.

  8

  If the term defined be relative, either in itself or in respect of

  its genus, see whether the definition fails to mention that to which

  the term, either in itself or in respect of its genus, is relative,

  e.g. if he has defined 'knowledge' as an 'incontrovertible conception'

  or 'wishing' as 'painless conation'. For of everything relative the

  essence is relative to something else, seeing that the being of

  every relative term is identical with being in a certain relation to

  something. He ought, therefore, to have said that knowledge is

  'conception of a knowable' and that wishing is 'conation for a

  good'. Likewise, also, if he has defined 'grammar' as 'knowledge of

  letters': whereas in the definition there ought to be rendered

  either the thing to which the term itself is relative, or that,

  whatever it is, to which its genus is relative. Or see if a relative

  term has been described not in relation to its end, the end in

  anything being whatever is best in it or gives its purpose to the

  rest. Certainly it is what is best or final that should be stated,

  e.g. that desire is not for the pleasant but for pleasure: for this is

  our purpose in choosing what is pleasant as well.

  Look and see also if that in relation to which he has rendered the

  term be a process or an activity: for nothing of that kind is an

  end, for the completion of the activity or process is the end rather

  than the process or activity itself. Or perhaps this rule is not

  true in all cases, for almost everybody prefers the present experience

  of pleasure to its cessation, so that they would count the activity as

  the end rather than its completion.

  Again see in some cases if he has failed to distinguish the quantity

  or quality or place or other differentiae of an object; e.g. the

  quality and quantity of the honour the striving for which makes a

  man ambitious: for all men strive for honour, so that it is not enough

  to define the ambitious man as him who strives for honour, but the

  aforesaid differentiae must be added. Likewise, also, in defining

  the covetous man the quantity of money he aims at, or in the case of

  the incontinent man the quality of the pleasures, should be stated.

  For it is not the man who gives way to any sort of pleasure whatever

  who is called incontinent, but only he who gives way to a certain kind

  of pleasure. Or again, people sometimes define night as a 'shadow on

  the earth', or an earthquake as a movement of the earth', or a cloud

  as 'condensation of the air', or a wind as a 'movement of the air';

  whereas they ought to specify as well quantity, quality, place, and

  cause. Likewise, also, in other cases of the kind: for by omitting any

  differentiae whatever he fails to state the essence of the term. One

  should always attack deficiency. For a movement of the earth does

  not constitute an earthquake, nor a movement of the air a wind,

  irrespective of its manner and the amount involved.

  Moreover, in the case of conations, and in any other cases where

  it applies, see if the word 'apparent' is left out, e.g. 'wishing is a

  conation after the good', or 'desire is a conation after the

  pleasant'-instead of saying 'the apparently good', or 'pleasant'.

  For often those who exhibit the conation do not perceive what is

  good or pleasant, so that their aim need not be really good or

  pleasant, but only apparently so. They ought, therefore, to have

  rendered the definition also accordingly. On the other hand, any one

  who maintains the existence of Ideas ought to be brought face to

  face with his Ideas, even though he does render the word in

  question: for there can be no Idea of anything merely apparent: the

  general view is that an Idea is always spoken of in relation to an

  Idea: thus absolute desire is for the absolutely pleasant, and

  absolute wishing is for the absolutely good; they therefore cannot

  be for an apparent good or an apparently pleasant: for the existence

  of an absolut
ely-apparently-good or pleasant would be an absurdity.

  9

  Moreover, if the definition be of the state of anything, look at

  what is in the state, while if it be of what is in the state, look

  at the state: and likewise also in other cases of the kind. Thus if

  the pleasant be identical with the beneficial, then, too, the man

  who is pleased is benefited. Speaking generally, in definitions of

  this sort it happens that what the definer defines is in a sense

  more than one thing: for in defining knowledge, a man in a sense

  defines ignorance as well, and likewise also what has knowledge and

  what lacks it, and what it is to know and to be ignorant. For if the

  first be made clear, the others become in a certain sense clear as

  well. We have, then, to be on our guard in all such cases against

  discrepancy, using the elementary principles drawn from

  consideration of contraries and of coordinates.

  Moreover, in the case of relative terms, see if the species is

  rendered as relative to a species of that to which the genus is

  rendered as relative, e.g. supposing belief to be relative to some

  object of belief, see whether a particular belief is made relative

  to some particular object of belief: and, if a multiple be relative to

  a fraction, see whether a particular multiple be made relative to a

  particular fraction. For if it be not so rendered, clearly a mistake

  has been made.

  See, also, if the opposite of the term has the opposite

  definition, whether (e.g.) the definition of 'half' is the opposite of

  that of 'double': for if 'double' is 'that which exceeds another by an

  equal amount to that other', 'half' is 'that which is exceeded by an

  amount equal to itself'. In the same way, too, with contraries. For to

  the contrary term will apply the definition that is contrary in some

  one of the ways in which contraries are conjoined. Thus (e.g.) if

  'useful'='productive of good', 'injurious'=productive of evil' or

  'destructive of good', for one or the other of thee is bound to be

  contrary to the term originally used. Suppose, then, neither of