by Aristotle
are desirable, and therefore it is we say that even God and the good
man possess them; for they are capable (we say) of doing evil. So then
'capacity' can never be the genus of anything blameworthy. Else, the
result will be that what is blameworthy is sometimes desirable: for
there will be a certain form of capacity that is blameworthy.
Also, see if he has put anything that is precious or desirable for
its own sake into the class 'capacity' or 'capable' or 'productive' of
anything. For capacity, and what is capable or productive of anything,
is always desirable for the sake of something else.
Or see if he has put anything that exists in two genera or more into
one of them only. For some things it is impossible to place in a
single genus, e.g. the 'cheat' and the 'slanderer': for neither he who
has the will without the capacity, nor he who has the capacity without
the will, is a slanderer or cheat, but he who has both of them.
Hence he must be put not into one genus, but into both the aforesaid
genera.
Moreover, people sometimes in converse order render genus as
differentia, and differentia as genus, defining (e.g.) astonishment as
'excess of wonderment' and conviction as 'vehemence of conception'.
For neither 'excess' nor 'vehemence' is the genus, but the
differentia: for astonishment is usually taken to be an 'excessive
wonderment', and conviction to be a 'vehement conception', so that
'wonderment' and 'conception' are the genus, while 'excess' and
'vehemence' are the differentia. Moreover, if any one renders 'excess'
and 'vehemence' as genera, then inanimate things will be convinced and
astonished. For 'vehemence' and 'excess' of a thing are found in a
thing which is thus vehement and in excess. If, therefore,
astonishment be excess of wonderment the astonishment will be found in
the wonderment, so that 'wonderment' will be astonished! Likewise,
also, conviction will be found in the conception, if it be
'vehemence of conception', so that the conception will be convinced.
Moreover, a man who renders an answer in this style will in
consequence find himself calling vehemence vehement and excess
excessive: for there is such a thing as a vehement conviction: if then
conviction be 'vehemence', there would be a 'vehement vehemence'.
Likewise, also, there is such a thing as excessive astonishment: if
then astonishment be an excess, there would be an 'excessive
excess'. Whereas neither of these things is generally believed, any
more than that knowledge is a knower or motion a moving thing.
Sometimes, too, people make the bad mistake of putting an
affection into that which is affected, as its genus, e.g. those who
say that immortality is everlasting life: for immortality seems to
be a certain affection or accidental feature of life. That this saying
is true would appear clear if any one were to admit that a man can
pass from being mortal and become immortal: for no one will assert
that he takes another life, but that a certain accidental feature or
affection enters into this one as it is. So then 'life' is not the
genus of immortality.
Again, see if to an affection he has ascribed as genus the object of
which it is an affection, by defining (e.g.) wind as 'air in
motion'. Rather, wind is 'a movement of air': for the same air
persists both when it is in motion and when it is still. Hence wind is
not 'air' at all: for then there would also have been wind when the
air was not in motion, seeing that the same air which formed the
wind persists. Likewise, also, in other cases of the kind. Even, then,
if we ought in this instance to admit the point that wind is 'air in
motion', yet we should accept a definition of the kind, not about
all those things of which the genus is not true, but only in cases
where the genus rendered is a true predicate. For in some cases,
e.g. 'mud' or 'snow', it is not generally held to be true. For
people tell you that snow is 'frozen water' and mud is earth mixed
with moisture', whereas snow is not water, nor mud earth, so that
neither of the terms rendered could be the genus: for the genus should
be true of all its species. Likewise neither is wine 'fermented
water', as Empedocles speaks of 'water fermented in wood';' for it
simply is not water at all.
6
Moreover, see whether the term rendered fail to be the genus of
anything at all; for then clearly it also fails to be the genus of the
species mentioned. Examine the point by seeing whether the objects
that partake of the genus fail to be specifically different from one
another, e.g. white objects: for these do not differ specifically from
one another, whereas of a genus the species are always different, so
that 'white' could not be the genus of anything.
Again, see whether he has named as genus or differentia some feature
that goes with everything: for the number of attributes that follow
everything is comparatively large: thus (e.g.) 'Being' and 'Unity' are
among the number of attributes that follow everything. If,
therefore, he has rendered 'Being' as a genus, clearly it would be the
genus of everything, seeing that it is predicated of everything; for
the genus is never predicated of anything except of its species. Hence
Unity, inter alia, will be a species of Being. The result,
therefore, is that of all things of which the genus is predicated, the
species is predicated as well, seeing that Being and Unity are
predicates of absolutely everything, whereas the predication of the
species ought to be of narrower range. If, on the other hand, he has
named as differentia some attribute that follows everything, clearly
the denotation of the differentia will be equal to, or wider than,
that of the genus. For if the genus, too, be some attribute that
follows everything, the denotation of the differentia will be equal to
its denotation, while if the genus do not follow everything, it will
be still wider.
Moreover, see if the description 'inherent in S' be used of the
genus rendered in relation to its species, as it is used of 'white' in
the case of snow, thus showing clearly that it could not be the genus:
for 'true of S' is the only description used of the genus in
relation to its species. Look and see also if the genus fails to be
synonymous with its species. For the genus is always predicated of its
species synonymously.
Moreover, beware, whenever both species and genus have a contrary,
and he places the better of the contraries inside the worse genus: for
the result will be that the remaining species will be found in the
remaining genus, seeing that contraries are found in contrary
genera, so that the better species will be found in the worse genus
and the worse in the better: whereas the usual view is that of the
better species the genus too is better. Also see if he has placed
the species inside the worse and not inside the better genus, when
it is at the same time related in like manner to both, as (e.g.) if he
has defined the 'soul'
as a 'form of motion' or 'a form of moving
thing'. For the same soul is usually thought to be a principle alike
of rest and of motion, so that, if rest is the better of the two, this
is the genus into which the soul should have been put.
Moreover, judge by means of greater and less degrees: if
overthrowing a view, see whether the genus admits of a greater degree,
whereas neither the species itself does so, nor any term that is
called after it: e.g. if virtue admits of a greater degree, so too
does justice and the just man: for one man is called 'more just than
another'. If, therefore, the genus rendered admits of a greater
degree, whereas neither the species does so itself nor yet any term
called after it, then what has been rendered could not be the genus.
Again, if what is more generally, or as generally, thought to be the
genus be not so, clearly neither is the genus rendered. The
commonplace rule in question is useful especially in cases where the
species appears to have several predicates in the category of essence,
and where no distinction has been drawn between them, and we cannot
say which of them is genus; e.g. both 'pain' and the 'conception of
a slight' are usually thought to be predicates of 'anger in the
category of essence: for the angry man is both in pain and also
conceives that he is slighted. The same mode of inquiry may be applied
also to the case of the species, by comparing it with some other
species: for if the one which is more generally, or as generally,
thought to be found in the genus rendered be not found therein, then
clearly neither could the species rendered be found therein.
In demolishing a view, therefore, you should follow the rule as
stated. In establishing one, on the other hand, the commonplace rule
that you should see if both the genus rendered and the species admit
of a greater degree will not serve: for even though both admit it,
it is still possible for one not to be the genus of the other. For
both 'beautiful' and 'white' admit of a greater degree, and neither is
the genus of the other. On the other hand, the comparison of the
genera and of the species one with another is of use: e.g. supposing A
and B to have a like claim to be genus, then if one be a genus, so
also is the other. Likewise, also, if what has less claim be a
genus, so also is what has more claim: e.g. if 'capacity' have more
claim than 'virtue' to be the genus of self-control, and virtue be the
genus, so also is capacity. The same observations will apply also in
the case of the species. For instance, supposing A and B to have a
like claim to be a species of the genus in question, then if the one
be a species, so also is the other: and if that which is less
generally thought to be so be a species, so also is that which is more
generally thought to be so.
Moreover, to establish a view, you should look and see if the
genus is predicated in the category of essence of those things of
which it has been rendered as the genus, supposing the species
rendered to be not one single species but several different ones:
for then clearly it will be the genus. If, on the other, the species
rendered be single, look and see whether the genus be predicated in
the category of essence of other species as well: for then, again, the
result will be that it is predicated of several different species.
Since some people think that the differentia, too, is a predicate of
the various species in the category of essence, you should distinguish
the genus from the differentia by employing the aforesaid elementary
principles-(a) that the genus has a wider denotation than the
differentia; (b) that in rendering the essence of a thing it is more
fitting to state the genus than the differentia: for any one who
says that 'man' is an 'animal' shows what man is better than he who
describes him as 'walking'; also (c) that the differentia always
signifies a quality of the genus, whereas the genus does not do this
of the differentia: for he who says 'walking' describes an animal of a
certain quality, whereas he who says 'animal' describes an animal of a
certain quality, whereas he who says 'animal' does not describe a
walking thing of a certain quality.
The differentia, then, should be distinguished from the genus in
this manner. Now seeing it is generally held that if what is
musical, in being musical, possesses knowledge in some respect, then
also 'music' is a particular kind of 'knowledge'; and also that if
what walks is moved in walking, then 'walking' is a particular kind of
'movement'; you should therefore examine in the aforesaid manner any
genus in which you want to establish the existence of something;
e.g. if you wish to prove that 'knowledge' is a form of
'conviction', see whether the knower in knowing is convinced: for then
clearly knowledge would be a particular kind of conviction. You should
proceed in the same way also in regard to the other cases of this
kind.
Moreover, seeing that it is difficult to distinguish whatever always
follows along with a thing, and is not convertible with it, from its
genus, if A follows B universally, whereas B does not follow A
universally-as e.g. 'rest' always follows a 'calm' and
'divisibility' follows 'number', but not conversely (for the divisible
is not always a number, nor rest a calm)-you may yourself assume in
your treatment of them that the one which always follows is the genus,
whenever the other is not convertible with it: if, on the other
hand, some one else puts forward the proposition, do not accept it
universally. An objection to it is that 'not-being' always follows
what is 'coming to be' (for what is coming to be is not) and is not
convertible with it (for what is not is not always coming to be),
and that still 'not-being' is not the genus of 'coming to be': for
'not-being' has not any species at all. Questions, then, in regard
to Genus should be investigated in the ways described.
Book V
1
THE question whether the attribute stated is or is not a property,
should be examined by the following methods:
Any 'property' rendered is always either essential and permanent
or relative and temporary: e.g. it is an 'essential property' of man
to be 'by nature a civilized animal': a 'relative property' is one
like that of the soul in relation to the body, viz. that the one is
fitted to command, and the other to obey: a 'permanent property' is
one like the property which belongs to God, of being an 'immortal
living being': a 'temporary property' is one like the property which
belongs to any particular man of walking in the gymnasium.
[The rendering of a property 'relatively' gives rise either to two
problems or to four. For if he at the same time render this property
of one thing and deny it of another, only two problems arise, as in
the case of a statement that it is a property of a man, in relation to
a horse, to be a biped. For one might try both to show that a man is
not a biped, and also that a hors
e is a biped: in both ways the
property would be upset. If on the other hand he render one apiece
of two attributes to each of two things, and deny it in each case of
the other, there will then be four problems; as in the case of a
statement that it is a property of a man in relation to a horse for
the former to be a biped and the latter a quadruped. For then it is
possible to try to show both that a man is not naturally a biped,
and that he is a quadruped, and also that the horse both is a biped,
and is not a quadruped. If you show any of these at all, the
intended attribute is demolished.]
An 'essential' property is one which is rendered of a thing in
comparison with everything else and distinguishes the said thing
from everything else, as does 'a mortal living being capable of
receiving knowledge' in the case of man. A 'relative' property is
one which separates its subject off not from everything else but
only from a particular definite thing, as does the property which
virtue possesses, in comparison with knowledge, viz. that the former
is naturally produced in more than one faculty, whereas the latter
is produced in that of reason alone, and in those who have a reasoning
faculty. A 'permanent' property is one which is true at every time,
and never fails, like being' compounded of soul and body', in the case
of a living creature. A 'temporary' property is one which is true at
some particular time, and does not of necessity always follow; as,
of some particular man, that he walks in the market-place.
To render a property 'relatively' to something else means to state
the difference between them as it is found either universally and
always, or generally and in most cases: thus a difference that is
found universally and always, is one such as man possesses in
comparison with a horse, viz. being a biped: for a man is always and
in every case a biped, whereas a horse is never a biped at any time.
On the other hand, a difference that is found generally and in most
cases, is one such as the faculty of reason possesses in comparison