Topics
By Aristotle
Written 350 B.C.E
Translated by W. A. Pickard-Cambridge
| Table
of Contents Book I |
 |
Part 1
Our treatise proposes to find a line of
inquiry whereby we shall be able to reason
from opinions that are generally accepted about every problem
propounded to us, and also shall ourselves,
when standing up to an argument, avoid
saying anything that will obstruct us. First, then, we must
say what reasoning is, and what its
varieties are, in order to grasp dialectical reasoning:
for this is the object of our search in the treatise before us.
Now reasoning is an argument in which, certain things being
laid down, something other than these
necessarily comes about through them. (a) It
is a 'demonstration', when the premisses from which the
reasoning starts are true and primary, or
are such that our knowledge of them has originally
come through premisses which are primary and true: (b)
reasoning, on the other hand, is
'dialectical', if it reasons from opinions that are generally accepted. Things are 'true' and
'primary' which are believed on the strength
not of anything else but of themselves: for in regard to the first principles of science it is improper
to ask any further for the why and wherefore
of them; each of the first principles should command belief in and by itself. On the other hand,
those opinions are 'generally accepted'
which are accepted by every one or by the majority or by the philosophers-i.e. by all, or by the majority,
or by the most notable and illustrious of
them. Again (c), reasoning is 'contentious' if it starts from opinions that seem to be generally
accepted, but are not really such, or again
if it merely seems to reason from opinions that are or seem
to be generally accepted. For not every
opinion that seems to be generally accepted
actually is generally accepted. For in none of the opinions
which we call generally accepted is the
illusion entirely on the surface, as happens
in the case of the principles of contentious arguments; for
the nature of the fallacy in these is
obvious immediately, and as a rule even to
persons with little power of comprehension. So then, of the
contentious reasonings mentioned, the former
really deserves to be called 'reasoning' as
well, but the other should be called 'contentious reasoning',
but not 'reasoning', since it appears to
reason, but does not really do so. Further (d),
besides all the reasonings we have mentioned there are the
mis-reasonings that start from the premisses
peculiar to the special sciences, as happens (for
example) in the case of geometry and her sister sciences. For
this form of reasoning appears to differ
from the reasonings mentioned above; the man
who draws a false figure reasons from things that are neither
true and primary, nor yet generally
accepted. For he does not fall within the definition;
he does not assume opinions that are received either by every
one or by the majority or by
philosophers-that is to say, by all, or by most,
or by the most illustrious of them-but he conducts his
reasoning upon assumptions which, though
appropriate to the science in question, are
not true; for he effects his mis-reasoning either by
describing the semicircles wrongly or by
drawing certain lines in a way in which they could
not be drawn.
The foregoing must stand for an outline survey of the species
of reasoning. In general, in regard both to
all that we have already discussed and to
those which we shall discuss later, we may remark that that
amount of distinction between them may
serve, because it is not our purpose to give
the exact definition of any of them; we merely want to
describe them in outline; we consider it
quite enough from the point of view of the line of
inquiry before us to be able to recognize each of them in
some sort of way.
Part 2
Next in order after the foregoing, we must say for how many
and for what purposes the treatise is
useful. They are three-intellectual training, casual
encounters, and the philosophical sciences. That it is useful
as a training is obvious on the face of it.
The possession of a plan of inquiry will
enable us more easily to argue about the subject proposed.
For purposes of casual encounters, it is
useful because when we have counted up the opinions
held by most people, we shall meet them on the ground not of
other people's convictions but of their own,
while we shift the ground of any argument
that they appear to us to state unsoundly. For the study of
the philosophical sciences it is useful,
because the ability to raise searching difficulties
on both sides of a subject will make us detect more easily the truth and error about the several points
that arise. It has a further use in relation
to the ultimate bases of the principles used in the several sciences. For it is impossible to discuss them
at all from the principles proper to the
particular science in hand, seeing that the principles are the prius of everything else: it is through the
opinions generally held on the particular
points that these have to be discussed, and this task belongs properly, or most appropriately, to
dialectic: for dialectic is a process of
criticism wherein lies the path to the principles of all inquiries.
Part 3
We shall be in perfect possession of the way to proceed when
we are in a position like that which we
occupy in regard to rhetoric and medicine and
faculties of that kind: this means the doing of that which we
choose with the materials that are
available. For it is not every method that the
rhetorician will employ to persuade, or the doctor to heal;
still, if he omits none of the available
means, we shall say that his grasp of the
science is adequate.
Part 4
First, then, we must see of what parts our inquiry consists.
Now if we were to grasp (a) with reference
to how many, and what kind of, things arguments
take place, and with what materials they start, and (h) how
we are to become well supplied with these,
we should have sufficiently won our goal.
Now the materials with which arguments start are equal in
number, and are identical, with the subjects
on which reasonings take place. For arguments
start with 'propositions', while the subjects on which
reasonings take place are 'problems'. Now
every proposition and every problem indicates either
a genus or a peculiarity or an
accident-for the differentia too, applying
as it does to a class (or genus),
should be ranked together with the genus. Since, however, of what is
peculiar to anything part signifies its
essence, while part does not, let us divide the 'peculiar'
into both the aforesaid parts, and call
that part which indicates the essence a 'definition', while of the remainder let us adopt the
terminology which is generally current
about these things, and speak of it as a 'property'. What we
have said, then, makes it clear that
according to our present division, the elements
turn out to be four, all told, namely either property or
definition or genus
or accident. Do not let any one suppose us to mean that each
of these enunciated by itself constitutes a
proposition or problem, but only that it is
from these that both problems and propositions are formed.
The difference between a problem and a
proposition is a difference in the turn of
the phrase. For if it be put in this way, "'An animal
that walks on two feet" is the
definition of man, is it not?' or '"Animal" is the genus of man, is it
not?' the result is a proposition: but if thus, 'Is "an
animal that walks on two feet" a
definition of man or no?' [or 'Is "animal" his genus or no?'] the
result is a problem. Similarly too in other cases. Naturally,
then, problems and propositions are equal
in number: for out of every proposition you
will make a problem if you change the turn of the phrase.
Part 5
We must now say what are 'definition', 'property', 'genus', and 'accident'.
A 'definition' is a phrase signifying a thing's essence. It is rendered in the form either of a phrase in
lieu of a term, or of a phrase in lieu of
another phrase; for it is sometimes possible to define the
meaning of a phrase as well. People whose
rendering consists of a term only, try it
as they may, clearly do not render the definition of the
thing in question, because a definition is
always a phrase of a certain kind. One may, however, use the word 'definitory' also of such a
remark as 'The "becoming" is
"beautiful"', and likewise also
of the question, 'Are sensation and knowledge the same or different?', for argument about definitions
is mostly concerned with questions of
sameness and difference. In a word we may call 'definitory' everything that falls under the same branch of
inquiry as definitions; and that all the
above-mentioned examples are of this character is clear on the face of them. For if we are able to
argue that two things are the same or are
different, we shall be well supplied by the same turn of
argument with lines of attack upon their
definitions as well: for when we have shown that
they are not the same we shall have demolished the
definition. Observe, please, that the
converse of this last statement does not hold: for to show that they are the same is not enough to
establish a definition. To show, however,
that they are not the same is enough of itself to overthrow it.
A 'property' is a predicate which does not indicate the
essence of a thing, but yet belongs to that
thing alone, and is predicated convertibly of
it. Thus it is a property of man to-be-capable of learning
grammar: for if A be a man, then he is
capable of learning grammar, and if he be capable
of learning grammar, he is a man. For no one calls anything a
'property' which may possibly belong to
something else, e.g. 'sleep' in the case of man,
even though at a certain time it may happen to belong to him
alone. That is to say, if any such thing
were actually to be called a property, it
will be called not a 'property' absolutely, but a 'temporary'
or a 'relative' property: for 'being on the
right hand side' is a temporary property, while 'two-footed'
is in point of fact ascribed as a property in certain
relations; e.g. it is a property of man
relatively to a horse and a dog. That nothing which
may belong to anything else than A is a convertible predicate
of A is clear: for it does not necessarily
follow that if something is asleep it is a
man.
A 'genus' is what is predicated in the
category of essence of a number of things
exhibiting differences in kind. We should treat as predicates
in the category of essence all such things
as it would be appropriate to mention in
reply to the question, 'What is the object before you?'; as, for example, in the case of man, if asked that
question, it is appropriate to say 'He is
an animal'. The question, 'Is one thing in the same genus as another or in
a different one?' is also a 'generic' question; for a question of that kind as well falls under the
same branch of inquiry as the genus: for having argued that 'animal' is
the genus of man, and likewise also of ox, we shall have argued that they are
in the same genus; whereas if we show that it is the genus
of the one but not of the other, we shall have
argued that these things are not in the same genus.
An 'accident' is (i) something which, though it is none of
the foregoing-i.e. neither a definition nor
a property nor a genus yet belongs to the thing: (something which may possibly
either belong or not belong to any one and
the self-same thing, as (e.g.) the 'sitting posture' may belong or not belong to some self-same thing.
Likewise also 'whiteness', for there is
nothing to prevent the same thing being at one time white, and at another not white. Of the definitions
of accident the second is the better: for
if he adopts the first, any one is bound, if he is to
understand it, to know already what
'definition' and 'genus' and
'property' are, whereas the second is
sufficient of itself to tell us the essential meaning of the term in question. To Accident are to be
attached also all comparisons of things
together, when expressed in language that is drawn in any
kind of way from what happens (accidit) to
be true of them; such as, for example, the
question, 'Is the honourable or the expedient preferable?'
and 'Is the life of virtue or the life of
self-indulgence the pleasanter?', and any
other problem which may happen to be phrased in terms like
these. For in all such cases the question
is 'to which of the two does the predicate in
question happen (accidit) to belong more closely?' It is
clear on the face of it that there is
nothing to prevent an accident from becoming a temporary
or relative property. Thus the sitting posture is an
accident, but will be a temporary property,
whenever a man is the only person sitting, while
if he be not the only one sitting, it is still a property
relatively to those who are not sitting. So
then, there is nothing to prevent an accident from
becoming both a relative and a temporary property; but a
property absolutely it will never be.
Part 6
We must not fail to observe that all remarks made in
criticism of a 'property' and 'genus' and 'accident' will be applicable
to 'definitions' as well. For when we have
shown that the attribute in question fails to belong
only to the term defined, as we do also in the case of a
property, or that the genus
rendered in the definition is not the true genus,
or that any of the things mentioned in the
phrase used does not belong, as would be
remarked also in the case of an accident, we shall have
demolished the definition; so that, to use
the phrase previously employed,' all the points
we have enumerated might in a certain sense be called
'definitory'. But we must not on this
account expect to find a single line of inquiry which
will apply universally to them all: for this is not an easy
thing to find, and, even were one found, it
would be very obscure indeed, and of little
service for the treatise before us. Rather, a special plan of
inquiry must be laid down for each of the
classes we have distinguished, and then,
starting from the rules that are appropriate in each case, it
will probably be easier to make our way
right through the task before us. So then,
as was said before,' we must outline a division of our
subject, and other questions we must
relegate each to the particular branch to which it
most naturally belongs, speaking of them as 'definitory' and
'generic' questions. The questions I mean
have practically been already assigned to
their several branches.
Part 7
First of all we must define the number of senses borne by the
term 'Sameness'. Sameness would be
generally regarded as falling, roughly speaking, into three divisions. We generally apply the
term numerically or specifically or
generically-numerically in cases where there is more than one
name but only one thing, e.g. 'doublet' and
'cloak'; specifically, where there is more
than one thing, but they present no differences in respect of
their species, as one man and another, or
one horse and another: for things like this
that fall under the same species are said to be 'specifically
the same'. Similarly, too, those things are
called generically the same which fall
under the same genus, such as a horse
and a man. It might appear that the sense
in which water from the same spring is called 'the same
water' is somehow different and unlike the
senses mentioned above: but really such a
case as this ought to be ranked in the same class with the
things that in one way or another are
called 'the same' in view of unity of species. For
all such things seem to be of one family and to resemble one
another. For the reaon why all water is
said to be specifically the same as all other
water is because of a certain likeness it bears to it, and
the only difference in the case of water
drawn from the same spring is this, that the
likeness is more emphatic: that is why we do not distinguish
it from the things that in one way or
another are called 'the same' in view of unity
of species. It is generally supposed that the term 'the same'
is most used in a sense agreed on by every
one when applied to what is numerically one.
But even so, it is apt to be rendered in more than one sense;
its most literal and primary use is found
whenever the sameness is rendered in
reference to an alternative name or definition, as when a
cloak is said to be the same as a doublet,
or an animal that walks on two feet is said to
be the same as a man: a second sense is when it is rendered
in reference to a property, as when what
can acquire knowledge is called the same as a
man, and what naturally travels upward the same as fire:
while a third use is found when it is
rendered in reference to some term drawn from Accident, as when the creature who is sitting, or who is
musical, is called the same as Socrates.
For all these uses mean to signify numerical unity. That what
I have just said is true may be best seen
where one form of appellation is
substituted for another. For often when we give the order to
call one of the people who are sitting
down, indicating him by name, we change our description,
whenever the person to whom we give the order happens not to understand us; he will, we think,
understand better from some accidental feature;
so we bid him call to us 'the man who is sitting' or 'who is
conversing over there'-clearly supposing
ourselves to be indicating the same object by
its name and by its accident.
Part 8
Of 'sameness' then, as has been said,' three senses are to be
distinguished. Now one way to confirm that
the elements mentioned above are those out of
which and through which and to which arguments proceed, is by
induction: for if any one were to survey
propositions and problems one by one, it would
be seen that each was formed either from the definition of
something or from its property or from its genus or from its accident. Another way to confirm it is through reasoning. For every
predicate of a subject must of necessity be
either convertible with its subject or not: and if it is convertible, it would be its definition or
property, for if it signifies the essence,
it is the definition; if not, it is a property: for this was what a property is, viz. what is predicated
convertibly, but does not signify the
essence. If, on the other hand, it is not predicated
convertibly of the thing, it either is or
is not one of the terms contained in the definition of the subject: and if it be one of those
terms, then it will be the genus or the differentia, inasmuch as the definition
consists of genus and differentiae; whereas, if it be not one of those terms,
clearly it would be an accident, for
accident was said' to be what belongs as an attribute to a
subject without being either its definition
or its genus or a property.
Part 9
Next, then, we must distinguish between the classes of
predicates in which the four orders in
question are found. These are ten in number: Essence,
Quantity, Quality, Relation, Place, Time, Position, State,
Activity, Passivity. For the accident and genus and property and definition of
anything will always be in one of these
categories: for all the propositions found through
these signify either something's essence or its quality or
quantity or some one of the other types of
predicate. It is clear, too, on the face of
it that the man who signifies something's essence signifies
sometimes a substance, sometimes a quality,
sometimes some one of the other types of
predicate. For when man is set before him and he says that
what is set there is 'a man' or 'an
animal', he states its essence and signifies a substance;
but when a white colour is set before him and he says that
what is set there is 'white' or is 'a
colour', he states its essence and signifies a
quality. Likewise, also, if a magnitude of a cubit be set
before him and he says that what is set
there is a magnitude of a cubit, he will be describing
its essence and signifying a quantity. Likewise, also, in the
other cases: for each of these kinds of
predicate, if either it be asserted of
itself, or its genus be asserted of
it, signifies an essence: if, on the other
hand, one kind of predicate is asserted of another kind, it
does not signify an essence, but a quantity
or a quality or one of the other kinds of
predicate. Such, then, and so many, are the subjects on which
arguments take place, and the materials
with which they start. How we are to
acquire them, and by what means we are to become well
supplied with them, falls next to be told.
Part 10
First, then, a definition must be given of a 'dialectical
proposition' and a 'dialectical problem'.
For it is not every proposition nor yet every problem
that is to be set down as dialectical: for no one in his
senses would make a proposition of what no
one holds, nor yet make a problem of what
is obvious to everybody or to most people: for the latter
admits of no doubt, while to the former no
one would assent. Now a dialectical proposition consists
in asking something that is held by all men or by most men or
by the philosophers, i.e. either by all, or
by most, or by the most notable of these,
provided it be not contrary to the general opinion; for a man
would probably assent to the view of the
philosophers, if it be not contrary to the
opinions of most men. Dialectical propositions also include
views which are like those generally
accepted; also propositions which contradict the
contraries of opinions that are taken to be generally
accepted, and also all opinions that are in
accordance with the recognized arts. Thus, supposing
it to be a general opinion that the knowledge of contraries
is the same, it might probably pass for a
general opinion also that the perception of
contraries is the same: also, supposing it to be a general
opinion that there is but one single
science of grammar, it might pass for a general opinion
that there is but one science of flute-playing as well,
whereas, if it be a general opinion that
there is more than one science of grammar, it
might pass for a general opinion that there is more than one
science of flute-playing as well: for all
these seem to be alike and akin. Likewise, also,
propositions contradicting the contraries of general opinions
will pass as general opinions: for if it be
a general opinion that one ought to do good
to one's friends, it will also be a general opinion that one ought not to do them harm. Here, that one
ought to do harm to one's friends is
contrary to the general view, and that one ought not to do
them harm is the contradictory of that
contrary. Likewise also, if one ought to do good
to one's friends, one ought not to do good to one's enemies:
this too is the contradictory of the view
contrary to the general view; the contrary
being that one ought to do good to one's enemies. Likewise,
also, in other cases. Also, on comparison,
it will look like a general opinion that
the contrary predicate belongs to the contrary subject: e.g.
if one ought to do good to one's friends,
one ought also to do evil to one's enemies. it
might appear also as if doing good to one's friends were a
contrary to doing evil to one's enemies:
but whether this is or is not so in reality as
well will be stated in the course of the discussion upon
contraries. Clearly also, all opinions that
are in accordance with the arts are dialectical propositions;
for people are likely to assent to the views held by those who have made a study of these things, e.g. on
a question of medicine they will agree with
the doctor, and on a question of geometry with the
geometrician; and likewise also in other
cases.
Part 11
A dialectical problem is a subject of inquiry that
contributes either to choice and avoidance,
or to truth and knowledge, and that either by
itself, or as a help to the solution of some other such
problem. It must, moreover, be something on
which either people hold no opinion either way,
or the masses hold a contrary opinion to the philosophers, or
the philosophers to the masses, or each of
them among themselves. For some problems it
is useful to know with a view to choice or avoidance, e.g. whether pleasure is to be chosen or not, while
some it is useful to know merely with a
view to knowledge, e.g. whether the universe is eternal or not: others, again, are not useful in and by
themselves for either of these purposes,
but yet help us in regard to some such problems; for there
are many things which we do not wish to
know in and by themselves, but for the sake
of other things, in order that through them we may come to
know something else. Problems also include
questions in regard to which reasonings conflict
(the difficulty then being whether so-and so is so or not,
there being convincing arguments for both
views); others also in regard to which we
have no argument because they are so vast, and we find it
difficult to give our reasons, e.g. the
question whether the universe is eternal or
no: for into questions of that kind too it is possible to inquire.
Problems, then, and propositions are to be defined as
aforesaid. A 'thesis' is a supposition of
some eminent philosopher that conflicts with
the general opinion; e.g. the view that contradiction is
impossible, as Antisthenes said; or the
view of Heraclitus that all things are in motion; or that Being is one, as Melissus says: for to
take notice when any ordinary person
expresses views contrary to men's usual opinions would be
silly. Or it may be a view about which we
have a reasoned theory contrary to men's usual
opinions, e.g. the view maintained by the sophists that what
is need not in every case either have come
to be or be eternal: for a musician who is
a grammarian 'is' so without ever having 'come to be' so, or
being so eternally. For even if a man does
not accept this view, he might do so on the
ground that it is reasonable.
Now a 'thesis' also is a problem, though a problem is not
always a thesis, inasmuch as some problems
are such that we have no opinion about them
either way. That a thesis, however, also forms a problem, is
clear: for it follows of necessity from
what has been said that either the mass of
men disagree with the philosophers about the thesis, or that
the one or the other class disagree among
themselves, seeing that the thesis is a
supposition in conflict with general opinion. Practically all
dialectical problems indeed are now called
'theses'. But it should make no difference whichever
description is used; for our object in thus distinguishing
them has not been to create a terminology,
but to recognize what differences happen to
be found between them.
Not every problem, nor every thesis, should be examined, but
only one which might puzzle one of those
who need argument, not punishment or perception.
For people who are puzzled to know whether one ought to
honour the gods and love one's parents or
not need punishment, while those who are
puzzled to know whether snow is white or not need perception.
The subjects should not border too closely
upon the sphere of demonstration, nor yet be
too far removed from it: for the former cases admit of no
doubt, while the latter involve
difficulties too great for the art of the trainer.
Part 12
Having drawn these definitions, we must distinguish how many
species there are of dialectical arguments.
There is on the one hand Induction, on the
other Reasoning. Now what reasoning is has been said before:
induction is a passage from individuals to
universals, e.g. the argument that supposing the
skilled pilot is the most effective, and likewise the skilled
charioteer, then in general the skilled man
is the best at his particular task. Induction is
the more convincing and clear: it is more readily learnt by
the use of the senses, and is applicable
generally to the mass of men, though reasoning is
more forcible and effective against contradictious people.
Part 13
The classes, then, of things about which, and of things out
of which, arguments are constructed, are to
be distinguished in the way we have said
before. The means whereby we are to become well supplied with
reasonings are four: (1) the securing of
propositions; (2) the power to distinguish
in how many senses particular expression is used; (3) the
discovery of the differences of things; (4)
the investigation of likeness. The last three,
as well, are in a certain sense propositions: for it is
possible to make a proposition
corresponding to each of them, e.g. (1) 'The desirable may mean either the honourable or the pleasant
or the expedient'; and (2) Sensation
differs from knowledge in that the latter may be recovered
again after it has been lost, while the
former cannot'; and (3) The relation of the
healthy to health is like that of the vigorous to vigour'.
The first proposition depends upon the use
of one term in several senses, the second upon
the differences of things, the third upon their likenesses.
Part 14
Propositions should be selected in a number of ways
corresponding to the number of distinctions
drawn in regard to the proposition: thus one
may first take in hand the opinions held by all or by most
men or by the philosophers, i.e. by all, or
most, or the most notable of them; or opinions
contrary to those that seem to be generally held; and, again,
all opinions that are in accordance with
the arts. We must make propositions also of
the contradictories of opinions contrary to those that seem
to be generally held, as was laid down
before. It is useful also to make them by
selecting not only those opinions that actually are accepted,
but also those that are like these, e.g.
'The perception of contraries is the same'-the knowledge
of them being so-and 'we see by admission of something into
ourselves, not by an emission'; for so it
is, too, in the case of the other senses; for
in hearing we admit something into ourselves; we do not emit;
and we taste in the same way. Likewise also
in the other cases. Moreover, all statements
that seem to be true in all or in most cases, should be taken
as a principle or accepted position; for
they are posited by those who do not also
see what exception there may be. We should select also from the written handbooks of argument, and should
draw up sketch-lists of them upon each
several kind of subject, putting them down under separate
headings, e.g. 'On Good', or 'On Life'-and
that 'On Good' should deal with every form
of good, beginning with the category of essence. In the
margin, too, one should indicate also the
opinions of individual thinkers, e.g. 'Empedocles said that the elements of bodies were four':
for any one might assent to the saying of
some generally accepted authority.
Of propositions and problems there are-to comprehend the
matter in outline-three divisions: for some
are ethical propositions, some are on
natural philosophy, while some are logical. Propositions such
as the following are ethical, e.g. 'Ought
one rather to obey one's parents or the
laws, if they disagree?'; such as this are logical, e.g. 'Is
the knowledge of opposites the same or
not?'; while such as this are on natural philosophy, e.g. 'Is the universe eternal or not?'
Likewise also with problems. The nature of
each of the aforesaid kinds of proposition is not easily
rendered in a definition, but we have to
try to recognize each of them by means of
the familiarity attained through induction, examining them in
the light of the illustrations given above.
For purposes of philosophy we must treat of these things
according to their truth, but for dialectic
only with an eye to general opinion. All
propositions should be taken in their most universal form;
then, the one should be made into many.
E.g. 'The knowledge of opposites is the same'; next,
'The knowledge of contraries is the same', and that 'of
relative terms'. In the same way these two
should again be divided, as long as division is
possible, e.g. the knowledge of 'good and evil', of 'white
and black', or 'cold and hot'. Likewise
also in other cases.
Part 15
On the formation, then, of propositions, the above remarks
are enough. As regards the number of senses
a term bears, we must not only treat of
those terms which bear different senses, but we must also try
to render their definitions; e.g. we must
not merely say that justice and courage are
called 'good' in one sense, and that what conduces to vigour and what conduces to health are called so in
another, but also that the former are so
called because of a certain intrinsic quality they themselves
have, the latter because they are
productive of a certain result and not because
of any intrinsic quality in themselves. Similarly also in
other cases.
Whether a term bears a number of specific meanings or one
only, may be considered by the following
means. First, look and see if its contrary bears
a number of meanings, whether the discrepancy between them be
one of kind or one of names. For in some
cases a difference is at once displayed even
in the names; e.g. the contrary of 'sharp' in the case of a
note is 'flat', while in the case of a
solid edge it is 'dull'. Clearly, then, the
contrary of 'sharp' bears several meanings, and if so, also
does 'sharp'; for corresponding to each of
the former terms the meaning of its contrary will
be different. For 'sharp' will not be the same when contrary
to 'dull' and to 'flat', though 'sharp' is
the contrary of each. Again Barhu ('flat', 'heavy')
in the case of a note has 'sharp' as its contrary, but in the
case of a solid mass 'light', so that Barhu
is used with a number of meanings, inasmuch
as its contrary also is so used. Likewise, also, 'fine' as
applied to a picture has 'ugly' as its
contrary, but, as applied to a house, 'ramshackle'; so that 'fine' is an ambiguous term.
In some cases there is no discrepancy of any sort in the
names used, but a difference of kind
between the meanings is at once obvious: e.g.
in the case of 'clear' and 'obscure': for sound is called
'clear' and 'obscure', just as 'colour' is
too. As regards the names, then, there is
no discrepancy, but the difference in kind between the
meanings is at once obvious: for colour is
not called 'clear' in a like sense to sound. This
is plain also through sensation: for of things that are the
same in kind we have the same sensation,
whereas we do not judge clearness by the same
sensation in the case of sound and of colour, but in the
latter case we judge by sight, in the
former by hearing. Likewise also with 'sharp' and
'dull' in regard to flavours and solid edges: here in the
latter case we judge by touch, but in the
former by taste. For here again there is no
discrepancy in the names used, in the case either of the
original terms or of their contraries: for
the contrary also of sharp in either sense is
'dull'.
Moreover, see if one sense of a term has a contrary, while
another has absolutely none; e.g. the
pleasure of drinking has a contrary in the pain
of thirst, whereas the pleasure of seeing that the diagonal
is incommensurate with the side has none,
so that 'pleasure' is used in more than one sense. To 'love' also, used of the frame of mind, has
to 'hate' as its contrary, while as used of
the physical activity (kissing) it has none: clearly, therefore, to 'love' is an ambiguous term.
Further, see in regard to their intermediates,
if some meanings and their contraries have an intermediate, others have none, or if both have one but not
the same one, e.g. 'clear' and 'obscure' in
the case of colours have 'grey' as an intermediate, whereas in the case of sound they have none, or, if
they have, it is 'harsh', as some people
say that a harsh sound is intermediate. 'Clear', then, is an ambiguous term, and likewise also 'obscure'.
See, moreover, if some of them have more
than one intermediate, while others have but one, as is the case with 'clear' and 'obscure', for in
the case of colours there are numbers of
intermediates, whereas in regard to sound there is but one, viz. 'harsh'.
Again, in the case of the contradictory opposite, look and
see if it bears more than one meaning. For
if this bears more than one meaning, then
the opposite of it also will be used in more than one
meaning; e.g. 'to fail to see' a phrase
with more than one meaning, viz. (1) to fail to
possess the power of sight, (2) to fail to put that power to
active use. But if this has more than one
meaning, it follows necessarily that 'to
see' also has more than one meaning: for there will be an
opposite to each sense of 'to fail to see';
e.g. the opposite of 'not to possess the
power of sight' is to possess it, while of 'not to put the
power of sight to active use', the opposite
is to put it to active use.
Moreover, examine the case of terms that denote the privation
or presence of a certain state: for if the
one term bears more than one meaning, then
so will the remaining term: e.g. if 'to have sense' be used
with more than one meaning, as applied to
the soul and to the body, then 'to be wanting in
sense' too will be used with more than one meaning, as
applied to the soul and to the body. That
the opposition between the terms now in question depends upon the privation or presence of a
certain state is clear, since animals
naturally possess each kind of 'sense', both as applied to
the soul and as applied to the body.
Moreover, examine the inflected forms. For if 'justly' has
more than one meaning, then 'just', also,
will be used with more than one meaning; for
there will be a meaning of 'just' to each of the meanings of
'justly'; e.g. if the word 'justly' be used
of judging according to one's own opinion, and
also of judging as one ought, then 'just' also will be used
in like manner. In the same way also, if
'healthy' has more than one meaning, then 'healthily'
also will be used with more than one meaning: e.g. if
'healthy' describes both what produces
health and what preserves health and what betokens
health, then 'healthily' also will be used to mean 'in such a
way as to produce' or 'preserve' or
'betoken' health. Likewise also in other
cases, whenever the original term bears more than one
meaning, the inflexion also that is formed
from it will be used with more than one meaning, and vice versa.
Look also at the classes of the predicates signified by the
term, and see if they are the same in all
cases. For if they are not the same, then
clearly the term is ambiguous: e.g. 'good' in the case of
food means 'productive of pleasure', and in
the case of medicine 'productive of health', whereas
as applied to the soul it means to be of a certain quality,
e.g. temperate or courageous or just: and
likewise also, as applied to 'man'. Sometimes
it signifies what happens at a certain time, as (e.g.) the
good that happens at the right time: for
what happens at the right time is called good.
Often it signifies what is of certain quantity, e.g. as
applied to the proper amount: for the
proper amount too is called good. So then the term
'good' is ambiguous. In the same way also 'clear', as applied
to a body, signifies a colour, but in
regard to a note it denotes what is 'easy to
hear'. 'Sharp', too, is in a closely similar case: for the
same term does not bear the same meaning in
all its applications: for a sharp note is a
swift note, as the mathematical theorists of harmony tell us,
whereas a sharp (acute) angle is one that
is less than a right angle, while a sharp dagger
is one containing a sharp angle (point).
Look also at the genera of the
objects denoted by the same term, and see
if they are different without being subaltern, as (e.g.)
'donkey', which denotes both the animal and
the engine. For the definition of them that
corresponds to the name is different: for the one will be
declared to be an animal of a certain kind,
and the other to be an engine of a certain kind.
If, however, the genera be subaltern,
there is no necessity for the definitions
to be different. Thus (e.g.) 'animal' is the genus of 'raven', and
so is 'bird'. Whenever therefore we say that the raven is a
bird, we also say that it is a certain kind
of animal, so that both the genera are
predicated of it. Likewise also whenever we
call the raven a 'flying biped animal', we
declare it to be a bird: in this way, then, as well, both the
genera are predicated of raven, and
also their definition. But in the case of genera that are not subaltern this does
not happen, for whenever we call a thing an
'engine', we do not call it an animal, nor vice versa.
Look also and see not only if the genera of
the term before you are different without
being subaltern, but also in the case of its contrary: for if its contrary bears several senses,
clearly the term before you does so as
well.
It is useful also to look at the definition that arises from
the use of the term in combination, e.g. of
a 'clear (lit. white) body' of a 'clear
note'. For then if what is peculiar in each case be
abstracted, the same expression ought to
remain over. This does not happen in the case of
ambiguous terms, e.g. in the cases just mentioned. For the
former will be body possessing such and
such a colour', while the latter will be 'a note
easy to hear'. Abstract, then, 'a body 'and' a note', and the
remainder in each case is not the same. It
should, however, have been had the meaning of
'clear' in each case been synonymous.
Often in the actual definitions as well ambiguity creeps in
unawares, and for this reason the
definitions also should be examined. If (e.g.) any
one describes what betokens and what produces health as
'related commensurably to health', we must
not desist but go on to examine in what sense he has used the term 'commensurably' in each case,
e.g. if in the latter case it means that
'it is of the right amount to produce health', whereas in the for it means that 'it is such as to
betoken what kind of state prevails'.
Moreover, see if the terms cannot be compared as 'more or
less' or as 'in like manner', as is the
case (e.g.) with a 'clear' (lit. white) sound
and a 'clear' garment, and a 'sharp' flavour and a 'sharp'
note. For neither are these things said to
be clear or sharp 'in a like degree', nor
yet is the one said to be clearer or sharper than the other.
'Clear', then, and 'sharp' are ambiguous.
For synonyms are always comparable; for they
will always be used either in like manner, or else in a
greater degree in one case.
Now since of genera that are
different without being subaltern the
differentiae also are different in kind, e.g. those of
'animal' and 'knowledge' (for the
differentiae of these are different), look and see if the meanings comprised under the same term
are differentiae of genera that are different without being subaltern, as
e.g. 'sharp' is of a 'note' and a 'solid'.
For being 'sharp' differentiates note from note, and likewise
also one solid from another. 'Sharp', then,
is an ambiguous term: for it forms
differentiae of genera that are
different without being subaltern.
Again, see if the actual meanings included under the same
term themselves have different
differentiae, e.g. 'colour' in bodies and 'colour' in tunes: for the differentiae of 'colour' in
bodies are 'sight-piercing' and 'sight
compressing', whereas 'colour' in melodies has not the same differentiae. Colour, then, is an ambiguous
term; for things that are the same have the
same differentiae.
Moreover, since the species is never the differentia of
anything, look and see if one of the
meanings included under the same term be a species and another a differentia, as (e.g.) clear'
(lit. white) as applied to a body is a
species of colour, whereas in the case of a note it is a
differentia; for one note is differentiated
from another by being 'clear'.
Part 16
The presence, then, of a number of meanings in a term may be
investigated by these and like means. The
differences which things present to each other should
be examined within the same genera, e.g. 'Wherein does
justice differ from courage, and wisdom
from temperance?'-for all these belong to the same
genus; and also from one genus to another, provided they be not
very much too far apart, e.g. 'Wherein does
sensation differ from knowledge?: for in
the case of genera that are very far
apart, the differences are entirely
obvious.
Part 17
Likeness should be studied, first, in the case of things
belonging to different genera, the formulae
being 'A:B = C:D' (e.g. as knowledge stands
to the object of knowledge, so is sensation related to the
object of sensation), and 'As A is in B, so
is C in D' (e.g. as sight is in the eye, so
is reason in the soul, and as is a calm in the sea, so is
windlessness in the air). Practice is more
especially needed in regard to terms that are
far apart; for in the case of the rest, we shall be more
easily able to see in one glance the points
of likeness. We should also look at things which
belong to the same genus, to see if
any identical attribute belongs to them
all, e.g. to a man and a horse and a dog; for in so far as
they have any identical attribute, in so
far they are alike.
Part 18
It is useful to have examined the number of meanings of a
term both for clearness' sake (for a man is
more likely to know what it is he asserts,
if it bas been made clear to him how many meanings it may
have), and also with a view to ensuring
that our reasonings shall be in accordance with
the actual facts and not addressed merely to the term used.
For as long as it is not clear in how many
senses a term is used, it is possible that
the answerer and the questioner are not directing their minds
upon the same thing: whereas when once it
has been made clear how many meanings there
are, and also upon which of them the former directs his mind
when he makes his assertion, the questioner
would then look ridiculous if he failed to
address his argument to this. It helps us also both to avoid being misled and to mislead by false
reasoning: for if we know the number of
meanings of a term, we shall certainly never be misled by
false reasoning, but shall know if the
questioner fails to address his argument to the same point; and when we ourselves put the questions
we shall be able to mislead him, if our
answerer happens not to know the number of meanings of our terms. This, however, is not possible in all
cases, but only when of the many senses
some are true and others are false. This manner of argument, however, does not belong properly to
dialectic; dialecticians should therefore by
all means beware of this kind of verbal discussion, unless
any one is absolutely unable to discuss the
subject before him in any other way.
The discovery of the differences of things helps us both in
reasonings about sameness and difference,
and also in recognizing what any particular thing
is. That it helps us in reasoning about sameness and
difference is clear: for when we have
discovered a difference of any kind whatever between the objects before us, we shall already have
shown that they are not the same: while it
helps us in recognizing what a thing is, because we usually distinguish the expression that is proper to
the essence of each particular thing by
means of the differentiae that are proper to it.
The examination of likeness is useful with a view both to
inductive arguments and to hypothetical
reasonings, and also with a view to the rendering of definitions. It is useful for inductive
arguments, because it is by means of an
induction of individuals in cases that are alike that we
claim to bring the universal in evidence:
for it is not easy to do this if we do not
know the points of likeness. It is useful for hypothetical
reasonings because it is a general opinion
that among similars what is true of one is
true also of the rest. If, then, with regard to any of them
we are well supplied with matter for a
discussion, we shall secure a preliminary admission that however it is in these cases, so it is
also in the case before us: then when we
have shown the former we shall have shown, on the strength of the hypothesis, the matter before us as
well: for we have first made the hypothesis
that however it is in these cases, so it is also in the case before us, and have then proved the point
as regards these cases. It is useful for
the rendering of definitions because, if we are able to see in one glance what is the same in each
individual case of it, we shall be at no
loss into what genus we ought to put
the object before us when we define it: for
of the common predicates that which is most definitely in the category of essence is likely to be the
genus. Likewise, also, in the case of objects widely divergent, the
examination of likeness is useful for
purposes of definition, e.g. the sameness of a calm at sea,
and windlessness in the air (each being a
form of rest), and of a point on a line and the unit
in number-each being a starting point. If, then, we render as
the genus what is
common to all the cases, we shall get the credit of defining not inappropriately. Definition-mongers too
nearly always render them in this way: they
declare the unit to be the startingpoint of number, and the point the startingpoint of a line. It is
clear, then, that they place them in that
which is common to both as their genus.
The means, then, whereby reasonings are effected, are these:
the commonplace rules, for the observance
of which the aforesaid means are useful,
are as follows.