by Aristotle
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.
Mo
reover, 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
establi
shing 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