Aristotle

by Various Works [lit]

  view, while the second is true. For there is no necessity that all the

  attributes that belong to the genus should belong also to the species;

  for 'animal' is flying and quadruped, but not so 'man'. All the

  attributes, on the other hand, that belong to the species must of

  necessity belong also to the genus; for if 'man' is good, then

  animal also is good. On the other hand, for purposes of overthrowing a

  view, the former argument is true while the latter is fallacious;

  for all the attributes which do not belong to the genus do not

  belong to the species either; whereas all those that are wanting to

  the species are not of necessity wanting to the genus.

  Since those things of which the genus is predicated must also of

  necessity have one of its species predicated of them, and since

  those things that are possessed of the genus in question, or are

  described by terms derived from that genus, must also of necessity

  be possessed of one of its species or be described by terms derived

  from one of its species (e.g. if to anything the term 'scientific

  knowledge' be applied, then also there will be applied to it the

  term 'grammatical' or 'musical' knowledge, or knowledge of one of

  the other sciences; and if any one possesses scientific knowledge or

  is described by a term derived from 'science', then he will also

  possess grammatical or musical knowledge or knowledge of one of the

  other sciences, or will be described by a term derived from one of

  them, e.g. as a 'grammarian' or a 'musician')-therefore if any

  expression be asserted that is in any way derived from the genus (e.g.

  that the soul is in motion), look and see whether it be possible for

  the soul to be moved with any of the species of motion; whether (e.g.)

  it can grow or be destroyed or come to be, and so forth with all the

  other species of motion. For if it be not moved in any of these

  ways, clearly it does not move at all. This commonplace rule is common

  for both purposes, both for overthrowing and for establishing a

  view: for if the soul moves with one of the species of motion, clearly

  it does move; while if it does not move with any of the species of

  motion, clearly it does not move.

  If you are not well equipped with an argument against the assertion,

  look among the definitions, real or apparent, of the thing before you,

  and if one is not enough, draw upon several. For it will be easier

  to attack people when committed to a definition: for an attack is

  always more easily made on definitions.

  Moreover, look and see in regard to the thing in question, what it

  is whose reality conditions the reality of the thing in question, or

  what it is whose reality necessarily follows if the thing in

  question be real: if you wish to establish a view inquire what there

  is on whose reality the reality of the thing in question will follow

  (for if the former be shown to be real, then the thing in question

  will also have been shown to be real); while if you want to

  overthrow a view, ask what it is that is real if the thing in question

  be real, for if we show that what follows from the thing in question

  is unreal, we shall have demolished the thing in question.

  Moreover, look at the time involved, to see if there be any

  discrepancy anywhere: e.g. suppose a man to have stated that what is

  being nourished of necessity grows: for animals are always of

  necessity being nourished, but they do not always grow. Likewise,

  also, if he has said that knowing is remembering: for the one is

  concerned with past time, whereas the other has to do also with the

  present and the future. For we are said to know things present and

  future (e.g. that there will be an eclipse), whereas it is

  impossible to remember anything save what is in the past.

  5

  Moreover, there is the sophistic turn of argument, whereby we draw

  our opponent into the kind of statement against which we shall be well

  supplied with lines of argument. This process is sometimes a real

  necessity, sometimes an apparent necessity, sometimes neither an

  apparent nor a real necessity. It is really necessary whenever the

  answerer has denied any view that would be useful in attacking the

  thesis, and the questioner thereupon addresses his arguments to the

  support of this view, and when moreover the view in question happens

  to be one of a kind on which he has a good stock of lines of argument.

  Likewise, also, it is really necessary whenever he (the questioner)

  first, by an induction made by means of the view laid down, arrives at

  a certain statement and then tries to demolish that statement: for

  when once this has been demolished, the view originally laid down is

  demolished as well. It is an apparent necessity, when the point to

  which the discussion comes to be directed appears to be useful, and

  relevant to the thesis, without being really so; whether it be that

  the man who is standing up to the argument has refused to concede

  something, or whether he (the questioner) has first reached it by a

  plausible induction based upon the thesis and then tries to demolish

  it. The remaining case is when the point to which the discussion comes

  to be directed is neither really nor apparently necessary, and it is

  the answerer's luck to be confuted on a mere side issue You should

  beware of the last of the aforesaid methods; for it appears to be

  wholly disconnected from, and foreign to, the art of dialectic. For

  this reason, moreover, the answerer should not lose his temper, but

  assent to those statements that are of no use in attacking the thesis,

  adding an indication whenever he assents although he does not agree

  with the view. For, as a rule, it increases the confusion of

  questioners if, after all propositions of this kind have been

  granted them, they can then draw no conclusion.

  Moreover, any one who has made any statement whatever has in a

  certain sense made several statements, inasmuch as each statement

  has a number of necessary consequences: e.g. the man who said 'X is

  a man' has also said that it is an animal and that it is animate and a

  biped and capable of acquiring reason and knowledge, so that by the

  demolition of any single one of these consequences, of whatever

  kind, the original statement is demolished as well. But you should

  beware here too of making a change to a more difficult subject: for

  sometimes the consequence, and sometimes the original thesis, is the

  easier to demolish.

  6

  In regard to subjects which must have one and one only of two

  predicates, as (e.g.) a man must have either a disease or health,

  supposing we are well supplied as regards the one for arguing its

  presence or absence, we shall be well equipped as regards the

  remaining one as well. This rule is convertible for both purposes: for

  when we have shown that the one attribute belongs, we shall have shown

  that the remaining one does not belong; while if we show that the

  one does not belong, we shall have shown that the remaining one does

  belong. Clearly then the rule is useful for both purposes.r />
  Moreover, you may devise a line of attack by reinterpreting a term

  in its literal meaning, with the implication that it is most fitting

  so to take it rather than in its established meaning: e.g. the

  expression 'strong at heart' will suggest not the courageous man,

  according to the use now established, but the man the state of whose

  heart is strong; just as also the expression 'of a good hope' may be

  taken to mean the man who hopes for good things. Likewise also

  'well-starred' may be taken to mean the man whose star is good, as

  Xenocrates says 'well-starred is he who has a noble soul'.' For a

  man's star is his soul.

  Some things occur of necessity, others usually, others however it

  may chance; if therefore a necessary event has been asserted to

  occur usually, or if a usual event (or, failing such an event

  itself, its contrary) has been stated to occur of necessity, it always

  gives an opportunity for attack. For if a necessary event has been

  asserted to occur usually, clearly the speaker has denied an attribute

  to be universal which is universal, and so has made a mistake: and

  so he has if he has declared the usual attribute to be necessary:

  for then he declares it to belong universally when it does not so

  belong. Likewise also if he has declared the contrary of what is usual

  to be necessary. For the contrary of a usual attribute is always a

  comparatively rare attribute: e.g. if men are usually bad, they are

  comparatively seldom good, so that his mistake is even worse if he has

  declared them to be good of necessity. The same is true also if he has

  declared a mere matter of chance to happen of necessity or usually;

  for a chance event happens neither of necessity nor usually. If the

  thing happens usually, then even supposing his statement does not

  distinguish whether he meant that it happens usually or that it

  happens necessarily, it is open to you to discuss it on the assumption

  that he meant that it happens necessarily: e.g. if he has stated

  without any distinction that disinherited persons are bad, you may

  assume in discussing it that he means that they are so necessarily.

  Moreover, look and see also if he has stated a thing to be an

  accident of itself, taking it to be a different thing because it has a

  different name, as Prodicus used to divide pleasures into joy and

  delight and good cheer: for all these are names of the same thing,

  to wit, Pleasure. If then any one says that joyfulness is an

  accidental attribute of cheerfulness, he would be declaring it to be

  an accidental attribute of itself.

  7

  Inasmuch as contraries can be conjoined with each other in six ways,

  and four of these conjunctions constitute a contrariety, we must grasp

  the subject of contraries, in order that it may help us both in

  demolishing and in establishing a view. Well then, that the modes of

  conjunction are six is clear: for either (1) each of the contrary

  verbs will be conjoined to each of the contrary objects; and this

  gives two modes: e.g. to do good to friends and to do evil to enemies,

  or per contra to do evil to friends and to do good to enemies. Or else

  (2) both verbs may be attached to one object; and this too gives two

  modes, e.g. to do good to friends and to do evil to friends, or to

  do good to enemies and to do evil to enemies. Or (3) a single verb may

  be attached to both objects: and this also gives two modes; e.g. to do

  good to friends and to do good to enemies, or to do evil to friends

  and evil to enemies.

  The first two then of the aforesaid conjunctions do not constitute

  any contrariety; for the doing of good to friends is not contrary to

  the doing of evil to enemies: for both courses are desirable and

  belong to the same disposition. Nor is the doing of evil to friends

  contrary to the doing of good to enemies: for both of these are

  objectionable and belong to the same disposition: and one

  objectionable thing is not generally thought to be the contrary of

  another, unless the one be an expression denoting an excess, and the

  other an expression denoting a defect: for an excess is generally

  thought to belong to the class of objectionable things, and likewise

  also a defect. But the other four all constitute a contrariety. For to

  do good to friends is contrary to the doing of evil to friends: for it

  proceeds from the contrary disposition, and the one is desirable,

  and the other objectionable. The case is the same also in regard to

  the other conjunctions: for in each combination the one course is

  desirable, and the other objectionable, and the one belongs to a

  reasonable disposition and the other to a bad. Clearly, then, from

  what has been said, the same course has more than one contrary. For

  the doing of good to friends has as its contrary both the doing of

  good to enemies and the doing of evil to friends. Likewise, if we

  examine them in the same way, we shall find that the contraries of

  each of the others also are two in number. Select therefore

  whichever of the two contraries is useful in attacking the thesis.

  Moreover, if the accident of a thing have a contrary, see whether it

  belongs to the subject to which the accident in question has been

  declared to belong: for if the latter belongs the former could not

  belong; for it is impossible that contrary predicates should belong at

  the same time to the same thing.

  Or again, look and see if anything has been said about something, of

  such a kind that if it be true, contrary predicates must necessarily

  belong to the thing: e.g. if he has said that the 'Ideas' exist in us.

  For then the result will be that they are both in motion and at

  rest, and moreover that they are objects both of sensation and of

  thought. For according to the views of those who posit the existence

  of Ideas, those Ideas are at rest and are objects of thought; while if

  they exist in us, it is impossible that they should be unmoved: for

  when we move, it follows necessarily that all that is in us moves with

  us as well. Clearly also they are objects of sensation, if they

  exist in us: for it is through the sensation of sight that we

  recognize the Form present in each individual.

  Again, if there be posited an accident which has a contrary, look

  and see if that which admits of the accident will admit of its

  contrary as well: for the same thing admits of contraries. Thus (e.g.)

  if he has asserted that hatred follows anger, hatred would in that

  case be in the 'spirited faculty': for that is where anger is. You

  should therefore look and see if its contrary, to wit, friendship,

  be also in the 'spirited faculty': for if not-if friendship is in

  the faculty of desire-then hatred could not follow anger. Likewise

  also if he has asserted that the faculty of desire is ignorant. For if

  it were capable of ignorance, it would be capable of knowledge as

  well: and this is not generally held-I mean that the faculty of desire

  is capable of knowledge. For purposes, then, of overthrowing a view,

  as has been said, this rule should be observed: but for purposes of
<
br />   establishing one, though the rule will not help you to assert that the

  accident actually belongs, it will help you to assert that it may

  possibly belong. For having shown that the thing in question will

  not admit of the contrary of the accident asserted, we shall have

  shown that the accident neither belongs nor can possibly belong; while

  on the other hand, if we show that the contrary belongs, or that the

  thing is capable of the contrary, we shall not indeed as yet have

  shown that the accident asserted does belong as well; our proof will

  merely have gone to this point, that it is possible for it to belong.

  8

  Seeing that the modes of opposition are four in number, you should

  look for arguments among the contradictories of your terms, converting

  the order of their sequence, both when demolishing and when

  establishing a view, and you should secure them by means of

  induction-such arguments (e.g.) as that man be an animal, what is

  not an animal is not a man': and likewise also in other instances of

  contradictories. For in those cases the sequence is converse: for

  'animal' follows upon 'man but 'not-animal' does not follow upon

  'not-man', but conversely 'not-man' upon 'not-animal'. In all cases,

  therefore, a postulate of this sort should be made, (e.g.) that 'If

  the honourable is pleasant, what is not pleasant is not honourable,

  while if the latter be untrue, so is the former'. Likewise, also,

  'If what is not pleasant be not honourable, then what is honourable is

  pleasant'. Clearly, then, the conversion of the sequence formed by

  contradiction of the terms of the thesis is a method convertible for

  both purposes.

  Then look also at the case of the contraries of S and P in the

  thesis, and see if the contrary of the one follows upon the contrary

  of the other, either directly or conversely, both when you are

  demolishing and when you are establishing a view: secure arguments

  of this kind as well by means of induction, so far as may be required.

  Now the sequence is direct in a case such as that of courage and

  cowardice: for upon the one of them virtue follows, and vice upon