by Aristotle
4
Comparisons of things together should therefore be conducted in
the manner prescribed. The same commonplace rules are useful also
for showing that anything is simply desirable or objectionable: for we
have only to subtract the excess of one thing over another. For if
what is more precious be more desirable, then also what is precious is
desirable; and if what is more useful be more desirable, then also
what is useful is desirable. Likewise, also, in the case of other
things which admit of comparisons of that kind. For in some cases in
the very course of comparing the things together we at once assert
also that each of them, or the one of them, is desirable, e.g.
whenever we call the one good 'by nature' and the other 'not by
nature': for dearly what is good by nature is desirable.
5
The commonplace rules relating to comparative degrees and amounts
ought to be taken in the most general possible form: for when so taken
they are likely to be useful in a larger number of instances. It is
possible to render some of the actual rules given above more universal
by a slight alteration of the expression, e.g. that what by nature
exhibits such and such a quality exhibits that quality in a greater
degree than what exhibits it not by nature. Also, if one thing does,
and another does not, impart such and such a quality to that which
possesses it, or to which it belongs, then whichever does impart it is
of that quality in greater degree than the one which does not impart
it; and if both impart it, then that one exhibits it in a greater
degree which imparts it in a greater degree.
Moreover, if in any character one thing exceeds and another falls
short of the same standard; also, if the one exceeds something which
exceeds a given standard, while the other does not reach that
standard, then clearly the first-named thing exhibits that character
in a greater degree. Moreover, you should judge by means of
addition, and see if A when added to the same thing as B imparts to
the whole such and such a character in a more marked degree than B, or
if, when added to a thing which exhibits that character in a less
degree, it imparts that character to the whole in a greater degree.
Likewise, also, you may judge by means of subtraction: for a thing
upon whose subtraction the remainder exhibits such and such a
character in a less degree, itself exhibits that character in a
greater degree. Also, things exhibit such and such a character in a
greater degree if more free from admixture with their contraries; e.g.
that is whiter which is more free from admixture with black. Moreover,
apart from the rules given above, that has such and such a character
in greater degree which admits in a greater degree of the definition
proper to the given character; e.g. if the definition of 'white' be 'a
colour which pierces the vision', then that is whiter which is in a
greater degree a colour that pierces the vision.
6
If the question be put in a particular and not in a universal
form, in the first place the universal constructive or destructive
commonplace rules that have been given may all be brought into use.
For in demolishing or establishing a thing universally we also show it
in particular: for if it be true of all, it is true also of some,
and if untrue of all, it is untrue of some. Especially handy and of
general application are the commonplace rules that are drawn from
the opposites and co-ordinates and inflexions of a thing: for public
opinion grants alike the claim that if all pleasure be good, then also
all pain is evil, and the claim that if some pleasure be good, then
also some pain is evil. Moreover, if some form of sensation be not a
capacity, then also some form of failure of sensation is not a failure
of capacity. Also, if the object of conception is in some cases an
object of knowledge, then also some form of conceiving is knowledge.
Again, if what is unjust be in some cases good, then also what is just
is in some cases evil; and if what happens justly is in some cases
evil, then also what happens unjustly is in some cases good. Also,
if what is pleasant is in some cases objectionable, then pleasure is
in some cases an objectionable thing. On the same principle, also,
if what is pleasant is in some cases beneficial, then pleasure is in
some cases a beneficial thing. The case is the same also as regards
the things that destroy, and the processes of generation and
destruction. For if anything that destroys pleasure or knowledge be in
some cases good, then we may take it that pleasure or knowledge is
in some cases an evil thing. Likewise, also, if the destruction of
knowledge be in some cases a good thing or its production an evil
thing, then knowledge will be in some cases an evil thing; e.g. if for
a man to forget his disgraceful conduct be a good thing, and to
remember it be an evil thing, then the knowledge of his disgraceful
conduct may be taken to be an evil thing. The same holds also in other
cases: in all such cases the premiss and the conclusion are equally
likely to be accepted.
Moreover you should judge by means of greater or smaller or like
degrees: for if some member of another genus exhibit such and such a
character in a more marked degree than your object, while no member of
that genus exhibits that character at all, then you may take it that
neither does the object in question exhibit it; e.g. if some form of
knowledge be good in a greater degree than pleasure, while no form
of knowledge is good, then you may take it that pleasure is not good
either. Also, you should judge by a smaller or like degree in the same
way: for so you will find it possible both to demolish and to
establish a view, except that whereas both are possible by means of
like degrees, by means of a smaller degree it is possible only to
establish, not to overthrow. For if a certain form of capacity be good
in a like degree to knowledge, and a certain form of capacity be good,
then so also is knowledge; while if no form of capacity be good,
then neither is knowledge. If, too, a certain form of capacity be good
in a less degree than knowledge, and a certain form of capacity be
good, then so also is knowledge; but if no form of capacity be good,
there is no necessity that no form of knowledge either should be good.
Clearly, then, it is only possible to establish a view by means of a
less degree.
Not only by means of another genus can you overthrow a view, but
also by means of the same, if you take the most marked instance of the
character in question; e.g. if it be maintained that some form of
knowledge is good, then, suppose it to be shown that prudence is not
good, neither will any other kind be good, seeing that not even the
kind upon which there is most general agreement is so. Moreover, you
should go to work by means of an hypothesis; you should claim that the
attribute, if it belongs or does not belong in one case, does so in
a like degree in all, e.g. that if t
he soul of man be immortal, so are
other souls as well, while if this one be not so, neither are the
others. If, then, it be maintained that in some instance the attribute
belongs, you must show that in some instance it does not belong: for
then it will follow, by reason of the hypothesis, that it does not
belong to any instance at all. If, on the other hand, it be maintained
that it does not belong in some instance, you must show that it does
belong in some instance, for in this way it will follow that it
belongs to all instances. It is clear that the maker of the hypothesis
universalizes the question, whereas it was stated in a particular
form: for he claims that the maker of a particular admission should
make a universal admission, inasmuch as he claims that if the
attribute belongs in one instance, it belongs also in all instances
alike.
If the problem be indefinite, it is possible to overthrow a
statement in only one way; e.g. if a man has asserted that pleasure is
good or is not good, without any further definition. For if he meant
that a particular pleasure is good, you must show universally that
no pleasure is good, if the proposition in question is to be
demolished. And likewise, also, if he meant that some particular
pleasure is not good you must show universally that all pleasure is
good: it is impossible to demolish it in any other way. For if we show
that some particular pleasure is not good or is good, the
proposition in question is not yet demolished. It is clear, then, that
it is possible to demolish an indefinite statement in one way only,
whereas it can be established in two ways: for whether we show
universally that all pleasure is good, or whether we show that a
particular pleasure is good, the proposition in question will have
been proved. Likewise, also, supposing we are required to argue that
some particular pleasure is not good, if we show that no pleasure is
good or that a particular pleasure is not good, we shall have produced
an argument in both ways, both universally and in particular, to
show that some particular pleasure is not good. If, on the other hand,
the statement made be definite, it will be possible to demolish it
in two ways; e.g. if it be maintained that it is an attribute of
some particular pleasure to be good, while of some it is not: for
whether it be shown that all pleasure, or that no pleasure, is good,
the proposition in question will have been demolished. If, however, he
has stated that only one single pleasure is good, it is possible to
demolish it in three ways: for by showing that all pleasure, or that
no pleasure, or that more than one pleasure, is good, we shall have
demolished the statement in question. If the statement be made still
more definite, e.g. that prudence alone of the virtues is knowledge,
there are four ways of demolishing it: for if it be shown that all
virtue is knowledge, or that no virtue is so, or that some other
virtue (e.g. justice) is so, or that prudence itself is not knowledge,
the proposition in question will have been demolished.
It is useful also to take a look at individual instances, in cases
where some attribute has been said to belong or not to belong, as in
the case of universal questions. Moreover, you should take a glance
among genera, dividing them by their species until you come to those
that are not further divisible, as has been said before:' for
whether the attribute is found to belong in all cases or in none,
you should, after adducing several instances, claim that he should
either admit your point universally, or else bring an objection
showing in what case it does not hold. Moreover, in cases where it
is possible to make the accident definite either specifically or
numerically, you should look and see whether perhaps none of them
belongs, showing e.g. that time is not moved, nor yet a movement, by
enumerating how many species there are of movement: for if none of
these belong to time, clearly it does not move, nor yet is a movement.
Likewise, also, you can show that the soul is not a number, by
dividing all numbers into either odd or even: for then, if the soul be
neither odd nor even, clearly it is not a number.
In regard then to Accident, you should set to work by means like
these, and in this manner.
Book IV
1
NEXT we must go on to examine questions relating to Genus and
Property. These are elements in the questions that relate to
definitions, but dialecticians seldom address their inquiries to these
by themselves. If, then, a genus be suggested for something that is,
first take a look at all objects which belong to the same genus as the
thing mentioned, and see whether the genus suggested is not predicated
of one of them, as happens in the case of an accident: e.g. if
'good' be laid down to be the genus of 'pleasure', see whether some
particular pleasure be not good: for, if so, clearly good' is not
the genus of pleasure: for the genus is predicated of all the
members of the same species. Secondly, see whether it be predicated
not in the category of essence, but as an accident, as 'white' is
predicated of 'snow', or 'self-moved' of the soul. For 'snow' is not a
kind of 'white', and therefore 'white' is not the genus of snow, nor
is the soul a kind of 'moving object': its motion is an accident of
it, as it often is of an animal to walk or to be walking. Moreover,
'moving' does not seem to indicate the essence, but rather a state
of doing or of having something done to it. Likewise, also, 'white':
for it indicates not the essence of snow, but a certain quality of it.
So that neither of them is predicated in the category of 'essence'.
Especially you should take a look at the definition of Accident, and
see whether it fits the genus mentioned, as (e.g.) is also the case in
the instances just given. For it is possible for a thing to be and not
to be self-moved, and likewise, also, for it to be and not to be
white. So that neither of these attributes is the genus but an
accident, since we were saying that an accident is an attribute
which can belong to a thing and also not belong.
Moreover, see whether the genus and the species be not found in
the same division, but the one be a substance while the other is a
quality, or the one be a relative while the other is a quality, as
(e.g.) 'slow' and 'swan' are each a substance, while 'white' is not
a substance but a quality, so that 'white' is not the genus either
of 'snow' or of 'swan'. Again, knowledge' is a relative, while
'good' and 'noble' are each a quality, so that good, or noble, is
not the genus of knowledge. For the genera of relatives ought
themselves also to be relatives, as is the case with 'double': for
multiple', which is the genus of 'double', is itself also a
relative. To speak generally, the genus ought to fall under the same
division as the species: for if the species be a substance, so too
should be the genus, and if the species be a quality, so too the genus
shou
ld be a quality; e.g. if white be a quality, so too should
colour be. Likewise, also, in other cases.
Again, see whether it be necessary or possible for the genus to
partake of the object which has been placed in the genus. 'To partake'
is defined as 'to admit the definition of that which is partaken.
Clearly, therefore, the species partake of the genera, but not the
genera of the species: for the species admits the definition of the
genus, whereas the genus does not admit that of the species. You
must look, therefore, and see whether the genus rendered partakes or
can possibly partake of the species, e.g. if any one were to render
anything as genus of 'being' or of 'unity': for then the result will
be that the genus partakes of the species: for of everything that
is, 'being' and 'unity' are predicated, and therefore their definition
as well.
Moreover, see if there be anything of which the species rendered
is true, while the genus is not so, e.g. supposing 'being' or
'object of knowledge' were stated to be the genus of 'object of
opinion'. For 'object of opinion' will be a predicate of what does not
exist; for many things which do not exist are objects of opinion;
whereas that 'being' or 'object of knowledge' is not predicated of
what does not exist is clear. So that neither 'being' nor 'object of
knowledge' is the genus of 'object of opinion': for of the objects
of which the species is predicated, the genus ought to be predicated
as well.
Again, see whether the object placed in the genus be quite unable to
partake of any of its species: for it is impossible that it should
partake of the genus if it do not partake of any of its species,
except it be one of the species reached by the first division: these
do partake of the genus alone. If, therefore, 'Motion' be stated as
the genus of pleasure, you should look and see if pleasure be
neither locomotion nor alteration, nor any of the rest of the given
modes of motion: for clearly you may then take it that it does not
partake of any of the species, and therefore not of the genus