Aristotle

by Various Works [lit]

  there are three ways: in the first place, see whether the contrary

  of the species be found in the genus stated, suppose the genus have no

  contrary: for if the contrary be 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

  have a contrary, look and see whether also 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.

  Again, consider in the case of the inflexions and the co-ordinates

  of species and genus, and see whether they follow likewise, 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 be 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 be not so, then neither is any of the

  rest of them.

  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 be a kind of 'good', then also the

  pleasant will be a kind of 'useful': for clearly it may be taken to be

  productive of good, seeing that pleasure is good. In the same way also

  consider the case of processes of generation and destruction; if

  (e.g.) to build be to be active, then to have built is to have been

  active, and if to learn be to recollect, then also to have learnt is

  to have recollected, and if to be decomposed be 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 capacities

  and uses of things; and in general, both in demolishing and in

  establishing an argument, 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: 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 capacity be a disposition,

  then also to be capable of something is to be disposed to it, and if

  the use of anything be an activity, then to use it is to be active,

  and to have used it is to have been active.

  If the opposite of the species be a privation, there are two ways of

  demolishing an argument, first of all by looking to see if the

  opposite be found in the genus rendered: for either the privation is

  to be found absolutely nowhere in the same genus, or at least not in

  the same ultimate genus: e.g. if the ultimate genus containing sight

  be sensation, then blindness will not be a sensation. Secondly, if

  there be a sensation. Secondly, if there be a privation opposed to

  both genus and species, but the opposite of the species be not found

  in the opposite of the genus, then neither could the species

  rendered be in the genus rendered. 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 be found in the

  opposite genus, then also the species in question would be found in

  the genus in question: e.g. if 'blindness' be a form of

  'insensibility', then 'sight' is a form of 'sensation'.

  Again, look at the negations of the genus and species and convert

  the order of terms, according to the method described in the case of

  Accident: e.g. if the pleasant be a kind of good, what is not good

  is not pleasant. For were this no something not good as well would

  then be pleasant. That, however, cannot be, for it is impossible, if

  'good' be the genus of pleasant, that anything not 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

  be not pleasant, then what is pleasant is good, so that 'good' is

  the genus of 'pleasant'.

  If the species be a relative term, see whether the genus be a

  relative term as well: for if the species be a relative term, so too

  is the genus, as is the case with 'double' and 'multiple': for each is

  a relative term. If, on the other hand, the genus be a relative

  term, there is no necessity that the species should be so as well: for

  'knowledge'is a relative term, but not so 'grammar'. Or possibly not

  even the first statement would be generally considered true: for

  virtue is a kind of 'noble' and a kind of 'good' thing, and yet, while

  'virtue' is a relative term, 'good' and 'noble' are not relatives

  but qualities. Again, see whether the species fails to be used in

  the same relation when called by its own name, and when called by

  the name of its genus: e.g. if the term 'double' be used to mean the

  double of a 'half', then also the term 'multiple' ought to be used

  to mean multiple of a 'half'. Otherwise 'multiple' could not be the

  genus of 'double'.

  Moreover, see whether the term fail to be used in the same

  relation both when called by the name of its genus, and also when

  called by those of all the genera of its genus. For if the double be a

  multiple of a half, then 'in excess of 'will also be used in

  relation to a 'half': and, in general, the double will be called by

  the names of all the higher genera in relation to a 'half'. An

  objection may be raised that there is no necessity for a term to be

  used in the same relation when called by its own name and when

  called by that of its genus: for 'knowledge' is called knowledge 'of

  an object', whereas it is called a 'state' and 'disposition' not of an

  'object' but of the 'soul'.

  Again, see whether the genus and the species be used in the same way

  in respect of the inflexions they take, e.g. datives and genitives and

  all the rest. For as the species is used, so should the genus be as

  well, as in the case of 'double' and its higher genera: for we say

  both 'double of' and 'multiple of' a thing. Likewise, also, in the

  case of 'knowledge': for both knowledge' itself and its genera, e.g.

  'disposition' and 'state', are said to be 'of' something. An objection

  may be raised that in some cases it is not so: for we say 'superior

  to' and 'contrary to' so and so, whereas 'other', which is the genus

  of these terms, demands not 'to' but 'than': for the expression is

  'other than' so and so.

  Again, see whether terms used in like case relationships 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 we say both a half of' and 'a

  fraction of' something. The case is the same also as regards both

  'knowledge' and 'conception': for these take a genitive, and by

  conversion an 'object of knowledge' and an 'object of conception'

  are both alike used with a dative. If, then, in any cases the

  constructions after conversion be 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 equal number of things: for the general view is that

  the uses of both are alike and equal in number, as is the case with

  'present' and 'grant'. For a present' is of something or to some

  one, and also a 'grant' is of something and to some one: and 'grant'

  is the genus of 'present', for a 'present' is a 'grant that need not

  be returned'. In some cases, however, the number of relations in which

  the terms are used happens not to be equal, for while 'double' is

  double of something, we speak of 'in excess' or 'greater' in

  something, as well as of or than something: for what is in excess or

  greater is always in excess in something, as well as in excess of

  something. 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 possibly it is not universally true that

  species and genus are used in relation to an equal number of things.

  See, also, if the opposite of the species have the opposite of the

  genus as its genus, e.g. whether, if 'multiple' be the genus of

  'double', 'fraction' be also the genus of 'half'. For the opposite

  of the genus should always be the genus of the opposite species. If,

  then, any one were to assert that knowledge is a kind of sensation,

  then also the object of knowledge will have to be a kind of object

  of sensation, whereas it is not: for an object of knowledge is not

  always an object of sensation: for objects of knowledge include some

  of the objects of intuition as well. Hence 'object of sensation' is

  not the genus of 'object of knowledge': and if this be so, neither

  is 'sensation' the genus of 'knowledge'.

  Seeing that of relative terms some are of necessity found in, or

  used of, the things in relation to which they happen at any time to be

  used (e.g. 'disposition' and 'state' and '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 term 'object of knowledge' be applied to the

  soul: for it is quite possible that the knowledge of itself should

  be possessed by the soul itself, but it is not necessary, for it is

  possible for this same knowledge to be found in some one else),

  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 the contrary should be found in

  the contrary or knowledge in the object of knowledge, unless the

  object of knowledge happen to be a soul or a man)-you 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

  the 'abiding of knowledge'. For 'abiding' is always found in that

  which abides, and is used of that, so that the abiding of knowledge

  also will be found in knowledge. Memory, then, is found in

  knowledge, seeing that it is the abiding of knowledge. But this is

  impossible, for memory is always found in the soul. The aforesaid

  commonplace rule is common to the subject of Accident as well: for

  it is all the same to say that 'abiding' is the genus of memory, or to

  allege that it is an accident of it. For if in any way whatever memory

  be the abiding 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 activity inside the genus 'state', e.g. by

  defining 'sensation' as 'movement communicated through the body':

  for sensation is a 'state', whereas movement is an 'activity'.

  Likewise, also, if he has said that memory is a 'state that is

  retentive of a conception', for memory is never a state, but rather an

  activity.

  They also make a bad mistake who rank a 'state' within the

  'capacity' that attends it, e.g. by defining 'good temper' as the

  'control of anger', and 'courage' and 'justice' as 'control of

  fears' and of 'gains': for the terms 'courageous' and

  'good-tempered' are applied to a man who is immune from passion,

  whereas 'self-controlled' describes 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 by it: but, for 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 'conception' as that of

  conviction'. For both of the things in 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 bas 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 emphatically is not pain.

  By the same reasoning, neither is conviction conception: for it is

  possible to have the same conception even without being convinced of

  it, whereas this is impossible if conviction be a species of

  conception: for it is impossible for a thing still to remain the

  same if it be entirely transferred out of its species, just as neither

  could the same animal at one time be, and at another not be, a man.

  If, on the other hand, any one says that a man who has a conception

  must of necessity be also convinced of it, then 'conception' and

  'conviction' will be used with an equal denotation, so that not even

  so could the former be the genus of the latter: for the denotation

  of the genus should be wider.

  See, also, whether both naturally come to be anywhere 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 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

  faculty of 'desires'. (for in this pleasure also is found), whereas

  'anger' is found in the 'spirited' faculty. Hence the terms rendered

  are not the genera, seeing that they do not naturally come to be in
/>
  the same faculty as the species. Likewise, also, if 'friendship' be

  found in the faculty of desires, you may take it that 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 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 genus attributed only in

  some particular respect: for it is the general view that the genus

  is not thus imparted only in some particular respect: for a man is not

  an animal in a particular respect, nor is grammar knowledge in a

  particular respect only. Likewise also in other instances. Look,

  therefore, and see if in the case of any of its species the genus be

  imparted only in a certain respect; e.g. if 'animal' has been

  described as 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' and 'object of

  perception' could not be the genus of 'animal'.

  Sometimes also people place the whole inside the part without

  detection, defining (e.g.) 'animal' as 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.

  See also if he has put anything that is blameworthy or objectionable

  into the class 'capacity' or 'capable', e.g. by defining a 'sophist'

  or a 'slanderer', or a 'thief' as '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 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