NOMENCLATURE, DEFINITION, PREDICABLES
Sec. 1. Precision of thought needs precision of language for the recording
of such thought and for communicating it to others. We can often
remember with great vividness persons, things, landscapes, changes and
actions of persons or things, without the aid of language (though words
are often mixed with such trains of imagery), and by this means may form
judgments and inferences in particular cases; but for general notions,
judgments and inferences, not merely about this or that man, or thing,
but about all men or all kinds of things, we need something besides the
few images we can form of them from observation. Even if we possess
generic images, say, of 'horse' or 'cat' (that is, images formed, like
composite photographs, by a coalescence of the images of all the horses
or cats we have seen, so that their common properties stand out and
their differences frustrate and cancel one another), these are useless
for precise thought; for the generic image will not correspond with the
general appearance of horse or cat, unless we have had proportional
experience of all varieties and have been impartially interested in all;
and, besides, what we want for general thought is not a generic image of
the appearance of things, though it were much more definite and fairly
representative than such images ever are, but a general representation
of their important characters; which may be connected with internal
organs, such as none but an anatomist ever sees. We require a symbol
connected with the general character of a thing, or quality, or process,
as scientifically determined, whose representative truth may be trusted
in ordinary cases, or may be verified whenever doubt arises. Such
symbols are for most purposes provided by language; Mathematics and
Chemistry have their own symbols.
Sec. 2. First there should be "a name for every important meaning": (a) A
Nomenclature, or system of the names of all classes of objects, adapted
to the use of each science. Thus, in Geology there are names for classes
of rocks and strata, in Chemistry for the elements and their compounds,
in Zoology and Botany for the varieties and species of animals and
plants, their genera, families and orders.
To have such names, however, is not the whole aim in forming a
scientific language; it is desirable that they should be systematically
significant, and even elegant. Names, like other instruments, ought to
be efficient, and the efficiency of names consists in conveying the most
meaning with the least effort. In Botany and Zoology this result is
obtained by giving to each species a composite name which includes that
of the genus to which it belongs. The species of Felidae given in chap.
xvii. Sec. 7, are called _Felis leo_ (lion), _Felis tigris_ (tiger), _Felis
leopardus_ (leopard), _Felis concolor_ (puma), _Felis lyncus_ (European
lynx), _Felis catus_ (wild cat). In Chemistry, the nomenclature is
extremely efficient. Names of the simpler compounds are formed by
combining the names of the elements that enter into them; as Hydrogen
Chloride, Hydrogen Sulphide, Carbon Dioxide; and these can be given
still more briefly and efficiently in symbols, as HCl, H_{2}S, CO_{2}.
The symbolic letters are usually initials of the names of the elements:
as C = Carbon, S = Sulphur; sometimes of the Latin name, when the common
name is English, as Fe = Iron. Each letter represents a fixed quantity
of the element for which it stands, viz., the atomic weight. The
number written below a symbol on the right-hand side shows how many
atoms of the element denoted enter into a molecule of the compound.
(b) A Terminology is next required, in order to describe and define the
things that constitute the classes designated by the nomenclature, and
to describe and explain their actions.
(i) A name for every integral part of an object, as head, limb,
vertebra, heart, nerve, tendon; stalk, leaf, corolla, stamen, pistil;
plinth, frieze, etc. (ii) A name for every metaphysical part or
abstract quality of an object, and for its degrees and modes; as
extension, figure, solidity, weight; rough, smooth, elastic, friable;
the various colours, red, blue, yellow, in all their shades and
combinations and so with sounds, smells, tastes, temperatures. The terms
of Geometry are employed to describe the modes of figure, as angular,
curved, square, elliptical; and the terms of Arithmetic to express the
degrees of weight, elasticity, temperature, pitch of sound. When other
means fail, qualities are suggested by the names of things which exhibit
them in a salient way; figures by such terms as amphitheatre, bowl-like,
pear-shaped, egg-shaped; colours by lias-blue, sky-blue, gentian-blue,
peacock-blue; and similarly with sounds, smells and tastes. It is also
important to express by short terms complex qualities, as harmony,
fragrance, organisation, sex, symmetry, stratification.
(iii) In the explanation of Nature we further require suitable names for
processes and activities: as deduction, conversion, verification,
addition, integration, causation, tendency, momentum, gravitation,
aberration, refraction, conduction, affinity, combination, germination,
respiration, attention, association, development.
There may sometimes be a difficulty in distinguishing the terms which
stand for qualities from those that express activities, since all
qualities imply activities: weight, for example, implies gravitation;
and the quality heat is also a kind of motion. The distinction aimed at
lies between a quality as perceived by means of an effect upon our
senses (as weight is resistance to our effort in lifting; heat, a
sensation when we approach fire), and that property of a body which is
conceived to account for its energy (as gravitation that brings a body
to the ground, or physical heat that expands an iron bar or works an
engine). The former class of words, expressing qualities, are chiefly
used in description: the latter class, expressing activities, are
chiefly needed in explanation. They correspond respectively, like
classification and explanation, with the static and dynamic aspects of
Nature.
The terms of ordinary language fall into the same classes as those of
science: they stand for things, classes of things, parts, or qualities,
or activities of things; but they are far less precise in their
signification. As long as popular thought is vague its language must be
vague; nor is it desirable too strictly to correct the language whilst
the thought is incorrigible. Much of the effect of poetry and eloquence
depends upon the elasticity and indirect suggestiveness of common terms.
Even in reasoning upon some subjects, it is a mistake to aim at an
unattainable precision. It is better to be vaguely right than exactly
wrong. In the criticism of manners, of fine art, or of literature, in
politics, religion and moral philosophy, what we are anxious to say is
often far from clear to ourselves; and it is better to indicate our
meaning approximately, or as we feel about it, than to convey a false
meaning, or to lose the warmth and colour that are the life of such
reflections. It is hard to decide whether more harm has been done by
sophists who take a base advantage of the vagueness of common terms, or
by honest paralogists (if I may use the word) who begin by deceiving
themselves with a plausible definiteness of expression, and go on to
propagate their delusions amongst followers eager for systematic insight
but ignorant of the limits of its possibility.
Sec. 3. A Definition is necessary (if possible) for every scientific name.
To define a name is to give a precise statement of its meaning or
connotation. The name to be defined is the subject of a proposition,
whose predicate is a list of the fundamental qualities common to the
things or processes which the subject denotes, and on account of
possessing which qualities this name is given to them.
Thus, a curve is a line of which no part is straight. The momentum of a
moving body is the product of its mass and its velocity (these being
expressed in numbers of certain units). Nitrogen is a transparent
colourless gas, atomic weight 14, specific gravity .9713, not readily
combining, etc. A lion is a monodelphian mammal, predatory, walking on
its toes, of nocturnal habits, with a short rounded head and muzzle;
dental formula: Incisors (3-3)/(3-3), canines (1-1)/(1/1), praemolars
(3-3)/(2-2), molars (1-1)/(1-1) = 30; four toes on the hind and five on
the fore foot, retractile claws, prickly tongue, light and muscular in
build, about 9-1/2 feet from muzzle to tip of tail, tawny in colour, the
males maned, with a tufted tail. If anything answers to this
description, it is called a lion; if not, not: for this is the meaning
of the name.
For ordinary purposes, it may suffice to give an Incomplete Definition;
that is, a list of qualities not exhaustive, but containing enough to
identify the things denoted by the given name; as if we say that a lion
is 'a large tawny beast of prey with a tufted tail.' Such purposes may
also be served by a Description; which is technically, a proposition
mentioning properties sufficient to distinguish the things denoted, but
not the properties that enter into the definition; as if nitrogen be
indicated as the gas that constitutes 4/5 of the atmosphere.
Sec. 4. The rules for testing a Definition are: I.--As to its Contents--
(1) It must state the whole connotation of the name to be defined.
(2) It must not include any quality derivative from the connotation.
Such a quality is called a Proprium. A breach of this rule can do no
positive harm, but it is a departure from scientific economy. There is
no need to state in the definition what can be derived from it; and
whatever can be derived by causation, or by mathematical demonstration,
should be exhibited in that manner.
(3) It must not mention any circumstance that is not a part of the
connotation, even though it be universally found in the things denoted.
Such a circumstance, if not derivable from the connotation, is called an
Accident. That, for example, the lion at present only inhabits the Old
World, is an accident: if a species otherwise like a lion were found in
Brazil, it would not be refused the name of lion on the score of
locality. Whilst, however, the rules of Logic have forbidden the
inclusion of proprium or accident in a definition, in fact the
definitions of Natural History often mention such attributes when
characteristic. Indeed, definitions of superordinate classes--Families
and Orders--not infrequently give qualities as generally found in the
subordinate classes, and at the same time mention exceptional cases in
which they do not occur.
II.--As to its Expression--
(4) A Definition must not include the very term to be defined, nor any
cognate. In defining 'lion' we must not repeat 'lion,' nor use
'leonine'; it would elucidate nothing.
(5) It must not be put in vague language.
(6) It must not be in a negative form, if a positive form be obtainable.
We must not be content to say that a lion is 'no vegetarian,' or 'no
lover of daylight.' To define a curve as a line 'always changing its
direction' may be better than as 'in no part straight.'
Sec. 5. The process of determining a Definition is inseparable from
classification. We saw that classification consists in distributing
things into groups according to their likenesses and differences,
regarding as a class those individuals which have most qualities in
common. In doing so we must, of course, recognise the common qualities
or points of likeness; and to enumerate these is to define the name of
the class. If we discover the qualities upon which a class is based by
direct observation and induction, by the same method we discover the
definition of its name.
We saw also that classification is not merely the determination of
isolated groups of things, but a systematic arrangement of such groups
in relation to one another. Hence, again, Definitions are not
independent, but relative to one another; and, of course, in the same
way as classes are relative. That is to say, as a class is placed in
subordination to higher or more comprehensive groups, so the definition
of its name is subordinate to that of their names; and as a class stands
in contrast with co-ordinate classes (those that are in the same degree
of subordination to the same higher groups), so the definition of its
name is in contrast or co-ordination with the definitions of their
names. Lion is subordinate to _Felis_, to Digitigrade, to Carnivore and
so on up to Animal; and, beyond the Animal Kingdom, to Phenomenon; it is
co-ordinate with tiger, puma, etc.; and more remotely it is
co-ordinate with dog, jackal, wolf, which come under _Canis_--a genus
co-ordinate with _Felis_. The definition of lion, therefore, is
subordinate to that of _Felis_, and to all above it up to Phenomenon;
and is co-ordinate with that of tiger, and with all species in the same
grade. This is the ground of the old method of definition _per genus et
differentiam_.
The genus being the next class above any species, the _differentia_ or
Difference consists of the qualities which mark that species in addition
to those that mark the genus, and which therefore distinguish it from
all other species of the same genus. In the above definition of lion,
for example, all the properties down to "light and muscular in build"
are generic, that is, are possessed by the whole genus, _Felis_; and the
remaining four (size, colour, tufted tail, and mane in the male) are the
Difference or specific properties, because in those points the lion
contrasts with the other species of that genus. Differences may be
exhibited thus:
_Lion._ _Tiger._
SIZE: about 9-1/2 feet from nose | About 10 feet.
to tip of tail. |
COLOUR: tawny. | Warm tawny, striped with black.
TAIL: tufted. | Tapering.
MANE: present in the male. | Both sexes maneless.
There are other differences in the shape of the skull. In defining lion,
then, it would have been enough to mention the genus and the properties
making up the Difference; because the properties of the genus may be
found by turning to the definition of the genus; and, on the principle
of economy, whatever it is enough to do it is right to do. To define 'by
genus and difference' is a point of elegance, when the genus is known;
but the only way of knowing it is to compare the individuals comprised
in it and in co-ordinate genera, according to the methods of scientific
classification. It may be added that, as the genus represents ancestral
derivation, the predication of genus in a definition indicates the
remote causes of the phenomena denoted by the name defined. And this way
of defining corresponds with the method of double naming by genus and
species: _Felis leo_, _Felis tigris_, etc.; _Vanessa Atalanta_,
_Vanessa Io_, etc.
The so-called Genetic Definition, chiefly used in Mathematics, is a rule
for constructing that which a name denotes, in such a way as to ensure
its possessing the tributes connoted by the name. Thus, for a circle:
Take any point and, at any constant distance from it, trace a line
returning into itself. In Chemistry a genetic definition of any compound
might be given in the form of directions for the requisite synthesis of
elements.
Sec. 6. The chief difficulty in the definition of scientific names consists
in determining exactly the nature of the things denoted by them, as in
classifying plants and animals. If organic species are free growths,
continually changing, however gradually, according as circumstances give
some advantage to one form over others, we may expect to find such
species branching into varieties, which differ considerably from one
another in some respects, though not enough to constitute distinct
species. This is the case; and, consequently, there arises some
uncertainty in collecting from all the varieties those attributes which
are common to the species as a whole; and, therefore, of course,
uncertainty in defining the species. The same difficulty may occur in
defining a genus, on account of the extent to which some of its species
differ from others, whilst having enough of the common character to
deter the classifier from forming a distinct genus on their account. On
the other hand the occurrence of numerous intermediate varieties may
make it difficult to distinguish genera or species at all. Even the
Kingdoms of plants and animals are hard to discriminate at the lowest
levels of organisation. Now, where there is a difficulty of
classification there must be a corresponding difficulty of definition.
It has been proposed in such cases to substitute a Type for a
Definition; to select some variety of a species, or species of a genus,
as exhibiting its character in an eminent degree, and to regard other
groups as belonging to the same species or genus, according as they
agree more with this type than with other types representing other
species or genera. But the selection of one group as typical implies a
recognition of its attributes as prevailing generally (though not
universally) throughout the species or genus; and to recognise these
attributes and yet refuse to enumerate them in a definition, seems to be
no great gain. To enumerate the attributes of the type as an Approximate
Definition of the species or genus, true of _most_ of the groups
constituting the species or genus, answers the same purpose, is more
explicit, and can mislead no one who really attends to the exposition.
An approximate definition is, indeed, less misleading than the
indication of a type; for the latter method seems to imply that the
group which is now typical has a greater permanence or reality than its
co-ordinate groups; whereas, for aught we know, one of the outside
varieties or species may even now be superseding and extinguishing it.
But the statement of a definition as approximate, is an honest
confession that both the definition and the classification are (like a
provisional hypothesis) merely the best account we can give of the
matter according to our present knowledge.
Sec. 7. The limits of Definition are twofold: (a) A name whose meaning
cannot be analysed cannot be defined. This limitation meets us only in
dealing with the names of the metaphysical parts or simple qualities of
objects under the second requisite of a Terminology. Resistance and
weight, colour and its modes, many names of sounds, tastes, smells, heat
and cold--in fact, whatever stands for an unanalysable perception,
cannot be made intelligible to any one who has not had experience of the
facts denoted; they cannot be defined, but only exemplified. A sort of
genetic definition may perhaps be attempted, as if we say that colour is
the special sensation of the cones of the retina, or that blue is the
sensation produced by a ray of light vibrating about 650,000,000,000,000
times a second; but such expressions can give no notion of our meaning
to a blind man, or to any one who has never seen a blue object. Nor can
we explain what heat is like, or the smell of tobacco, to those who have
never experienced them; nor the sound of C 128 to one who knows nothing
of the musical scale.
If we distinguish the property of an object from the sensation it
excites in us, we may define any simple property as 'the power of
producing the sensation'; the colour of a flower as the power of
exciting the sensation of colour in us. Still, this gives no information
to the blind nor to the colour-blind. Abstract names may be defined by
defining the corresponding concrete: the definition of 'human nature' is
the same as of 'man.' But if the corresponding concrete be a simple
sensation (as blue), this being indefinable, the abstract (blueness) is
also indefinable.
(b) The second limit of Definition is the impossibility of exhausting
infinity, which would be necessary in order to convey the meaning of the
name of any individual thing or person. For, as we saw in chap. iv., if
in attempting to define a proper name we stop short of infinity, our
list of qualities or properties may possibly be found in two
individuals, and then it becomes the definition of a class-name or
general name, however small the actual class. Hence we can only give a
Description of that which a proper name denotes, enumerating enough of
its properties to distinguish it from everything else as far as our
knowledge goes.
Sec. 8. The five Predicables (Species, Genus, Difference, Proprium,
Accident) may best be discussed in connection with Classification and
Definition; and in giving an account of Classification, most of what has
to be said about them has been anticipated. Their name, indeed, connects
them with the doctrine of Propositions; for Predicables are terms that
may be predicated, classified according to their connotative relation to
the subject of a proposition (that is, according to the relation in
which their connotation stands to the connotation of the subject):
nevertheless, the significance of the relations of such predicates to a
subject is derivative from the general doctrine of classification.
For example, in the proposition 'X is Y,' Y must be one of the five
sorts of predicables in relation to X; but of what sort, depends upon
what X (the subject) is, or means. The subject of the proposition must
be either a definition, or a general connotative name, or a singular
name.
If X be a definition, Y must be a species; for nothing but a general
name can be predicated of a definition: and, strictly speaking, it is
only in relation to a definition (as subject) that species can be a
predicable; when it is called _Species predicabilis_ (1).
If X be a connotative name, it is itself a species (_Species
subjicibilis_); and the place of the subject of a proposition is the
usual one for species. The predicate, Y, may then be related to the
species in three different ways. First, it may be a definition, exactly
equivalent to the species;--in fact, nothing else than the species in an
explicit form, the analysis of its connotation. Secondly, the predicate
may be, or connote, some _part only_ of the definition or connotation of
the species; and then it is either genus (2), or difference (3).
Thirdly, the predicate may connote _no part_ of the definition, and then
it is either derivable from it, being a proprium (4), or not derivable
from it, being an accident (5). These points of doctrine will be
expanded and illustrated in subsequent pages.
If X be a singular name, deriving connotation from its constituent terms
(chap. iv. Sec. 2), as 'The present Emperor of China,' it may be treated as
a _Species subjicibilis_. Then that he is 'an absolute monarch,'
predicates a genus; because that is a genus of 'Emperor,' a part of the
singular name that gives it connotation. That he wears a yellow robe is
a proprium, derivable from the ceremonial of his court. That he is
thirty years of age is an accident.
But if X be a proper name, having no connotation, Y must always be an
accident; since there can then be no definition of X, and therefore
neither species, genus, difference, nor proprium. Hence, that 'John Doe
is a man' is an accidental proposition: 'man' is not here a _Species
predicabilis_; for the name might have been given to a dog or a
mountain. That is what enables the proposition to convey information: it
would be useless if the proper name implied 'humanity.'
'Species' is most frequently used (as in Zoology) for the _class
denoted_ by a general name; but in Logic it is better to treat it as a
general name used connotatively for the attributes possessed in common
by the things denoted, and on account of which they are regarded as a
class: it is sometimes called the Essence (Sec. 9). In this connotative
sense, a species is implicitly what the definition is explicitly; and
therefore the two are always simply convertible. Thus, 'A plane
triangle' (species) is 'a figure enclosed by three straight lines'
(definition): clearly we may equally say, 'A figure enclosed by three
straight lines is a plane triangle.' It is a simple identity.
A genus is also commonly viewed denotatively, as a class containing
smaller classes, its species; but in Logic it is, again, better to treat
it connotatively, as a name whose definition is part of the definition
of a given species.
A difference is the remainder of the definition of any species after
subtracting a given genus. Hence, the genus and difference together make
up the species; whence the method of definition _per genus et
differentiam_ (_ante_, Sec. 5).
Whilst in Botany and Zoology the species is fixed at the lowest step of
the classification (varieties not being reckoned as classes), and the
genus is also fixed on the step next above it, in Logic these
predicables are treated as movable up and down the ladder: any lower
class being species in relation to any higher; which higher class,
wherever taken, thus becomes a genus. Lion may logically be regarded as
a species of digitigrade, or mammal, or animal; and then each of these
is a genus as to lion: or, again, digitigrade may be regarded as a
species of mammal, or mammal as a species of animal. The highest class,
however, is never a species; wherefore it is called a _Summum Genus_:
and the lowest class is never a genus; wherefore it is called an _Infima
Species_. Between these two any step may be either species or genus,
according to the relation in which it is viewed to other classes, and is
then called Subaltern. The _summum genus_, again, may be viewed in
relation to a _given_ universe or _suppositio_ (that is, any limited
area of existence now the object of attention), or to the _whole_
universe. If we take the animal kingdom as our _suppositio_, Animal is
the _summum genus_; but if we take the whole universe, 'All things' is
the _summum genus_.
"Porphyry's tree" is used to illustrate this doctrine. It begins with a
_summum genus_, 'Substance,' and descends by adding differences, step by
step, to the _infima species_, 'Man.' It also illustrates Division by
Dichotomy.
SUBSTANCE
/ \
CORPOREAL || INCORPOREAL
||
BODY
/ \
ANIMATE || INANIMATE
||
LIVING BODY
/ \
SENSIBLE || INSENSIBLE
||
ANIMAL
/ \
RATIONAL || IRRATIONAL
||
MAN
//||\\
// || \\
// || \\
// || \\
// || \\
// || \\
// || \\
_Socrates_ _Plato_ _Aristotle_
Beginning with 'Substance,' as _summum genus_, and adding the
difference 'Corporeal,' we frame the species 'Body.' Taking 'Body' as
the genus and adding the difference 'Animate,' we frame the species
'Living Body;' and so on till 'Man' is reached; which, being _infima
species_, is only subdivisible into individuals. But the division of Man
into individuals involves a change of principle; it is a division of the
denotation, not an increase of the connotation as in the earlier steps.
Only one side of each dichotomy is followed out in the 'tree': if the
other side had been taken, Incorporeal Substance would be 'Spirit';
which might be similarly subdivided.
Genus and species, then, have a double relation. In denotation the genus
includes the species; in connotation the species includes the genus.
Hence the doctrine that by increasing the connotation of a name we
decrease its denotation: if, for example, to the definition of 'lion' we
add 'inhabiting Africa,' Asiatic lions are no longer denoted by it. On
the other hand, if we use a name to denote objects that it did not
formerly apply to, some of the connotation must be dropped: if, for
example, the name 'lion' be used to include 'pumas,' the tufted tail and
mane can no longer be part of the meaning of the word; since pumas have
not these properties.
This doctrine is logically or formally true, but it may not always be
true in fact. It is logically true; because wherever we add to the
connotation of a name, it is possible that some things to which it
formerly applied are now excluded from its denotation, though we may not
know of any such things. Still, as a matter of fact, an object may be
discovered to have a property previously unknown, and this property may
be fundamental and co-extensive with the denotation of its name, or even
more widely prevalent. The discovery that the whale is a mammal did not
limit the class 'whale'; nor did the discovery that lions, dogs, wolves,
etc., walk upon their toes, affect the application of any of these
names.
Similarly, the extension of a name to things not previously denoted by
it, may not in fact alter its definition; for the extension may be made
on the very ground that the things now first denoted by it have been
found to have the properties enumerated in its definition, as when the
name 'mammal' was applied to whales, dolphins, etc. If, however,
'mammal' had formerly been understood to apply only to land animals, so
that its definition included (at least, popularly) the quality of
'living on the land,' this part of the connotation was of course lost
when the denotation came to include certain aquatic animals.
A proprium is an attribute derived from the definition: being either (a)
implied in it, or deducible from it, as 'having its three angles equal
to two right angles' may be proved from the definition of a triangle; or
(b) causally dependent on it, as being 'dangerous to flocks' results
from the nature of a wolf, and as 'moving in an ellipse' results from
the nature of a planet in its relation to the sun.
An accident is a property accompanying the defining attributes without
being deducible from them. The word suggests that such a property is
merely 'accidental,' or there 'by chance'; but it only means that we do
not understand the connection.
Proprium and Accident bear the same relation to one another as
Derivative and Empirical Laws: the predication of a proprium is a
derivative law, and the predication of an accident is an empirical law.
Both accidents and empirical laws present problems, the solution of
which consists in reducing them, respectively, to propria and derivative
laws. Thus the colour of animals was once regarded as an accident for
which no reason could be given; but now the colour of animals is
regarded as an effect of their nature and habits, the chief determinants
of it being the advantage of concealment; whilst in other cases, as
among brightly coloured insects and snakes, the determinant may be the
advantage of advertising their own noxiousness. If such reasoning is
sound, colour is a proprium (and if so, it cannot _logically_ be
included in a definition; but it is better to be judicious than formal).
If the colour of animals is a proprium, we must recognise a distinction
between Inseparable and Separable Propria, according as they do, or do
not, always accompany the essence: for mankind is regarded as one
species; but each colour, white, black or yellow, is separable from it
under different climatic conditions; whilst tigers are everywhere
coloured and striped in much the same way; so that we may consider their
colouring as inseparable, in spite of exceptional specimens black or
white or clouded.
The same distinction may be drawn between accidents. 'Inhabiting Asia'
is an Inseparable Accident of tiger, but a Separable Accident of lion.
Even the occasional characteristics and occupations of individuals are
sometimes called separable accidents of the species; as, of man, being
colour-blind, carpentering, or running.
A proprium in the original signification of the term [Greek: hidion] was
peculiar to a species, never found with any other, and was therefore
convertible with the subject; but this restriction is no longer insisted on.
Sec. 9. Any predication of a genus, difference or definition, is a verbal,
analytic, or essential proposition: and any predication of a proprium or
accident, is a real, synthetic, or accidental proposition (chap. v. Sec.
6). A proposition is called verbal or analytic when the predicate is a
part, or the whole, of the meaning of the subject; and the subject being
species, a genus or difference is part, and a definition is the whole,
of its meaning or connotation. Hence such a proposition has also been
called explicative. Again, a proposition is called real or synthetic
when the predicate is no part of the meaning of the subject; and, the
subject being species, a proprium or accident is no part of its meaning
or connotation. Hence such a proposition has been called ampliative.
As to Essential and Accidental, these terms are derived from the
doctrine of Realism. Realists maintain that the essence of a thing, or
that which makes a thing to be what (or of what kind) it is, also makes
everything else of the same kind to be what it is. The essence, they
say, is not proper to each thing or separately inherent in it, but is an
'Universal' common to all things of that kind. Some hold that the
universal nature of things of any kind is an Idea existing (apart from
the things) in the intelligible world, invisible to mortal eye and only
accessible to thought; whence the Idea is called a noumenon: that only
the Idea is truly real, and that the things (say, trees, bedsteads and
cities) which appear to us in sense-perception, and which therefore are
called phenomena, only exist by participating in, or imitating, the Idea
of each kind of them. The standard of this school bears the legend
_Universalia ante rem_.
But others think that the Universal does not exist apart from particular
things, but is their present essence; gives them actuality as individual
substances; "informs" them, or is their formal cause, and thus makes
them to be what they are of their kind according to the definition: the
universal lion is in all lions, and is not merely similar, but identical
in all; for thus the Universal Reason thinks and energises in Nature.
This school inscribes upon its banners, _Universalia in re_.
To define anything, then, is to discover its essence, whether
transcendent or immanent; and to predicate the definition, or any part
of it (genus or difference), is to enounce an essential proposition. But
a proprium, being no part of a definition, though it always goes along
with it, does not show what a thing is; nor of course does an accident;
so that to predicate either of these is to enounce an accidental
proposition.
Another school of Metaphysicians denies the existence of Universal Ideas
or Forms; the real things, according to them, are individuals; which,
so far as any of them resemble one another, are regarded as forming
classes; and the only Universal is the class-name, which is applied
universally in the same sense. Hence, they are called Nominalists. The
sense in which any name is applied, they say, is derived from a
comparison of the individuals, and by abstraction of the properties they
have in common; and thus the definition is formed. _Universalia post
rem_ is their motto. Some Nominalists, however, hold that, though
Universals do not exist in nature, they do in our minds, as Abstract
Ideas or Concepts; and that to define a term is to analyse the concept
it stands for; whence, these philosophers are called Conceptualists.
Such questions belong to Metaphysics rather than to Logic; and the
foregoing is a commonplace account of a subject upon every point of
which there is much difference of opinion.
Sec. 10. The doctrine of the Predicaments, or Categories, is so interwoven
with the history of speculation and especially of Logic that, though its
vitality is exhausted, it can hardly be passed over unmentioned. The
predicaments of Aristotle are the heads of a classification of terms as
possible predicates of a particular thing or individual. Hamilton
(_Logic_: Lect. xi.) has given a classification of them; which, if it
cannot be found in Aristotle, is an aid to the memory, and may be thrown
into a table thus:
Substance [Greek: ousia] (1)
{Quantity [Greek: poson] (2)
Attribute {Quality [Greek: poion] (3)
{Relation [Greek: pros ti] (4)
{ Where [Greek: pou] (5)
{ When [Greek: pote] (6)
{ Action [Greek: poiein] (7)
Modes of Relation { Passion [Greek: paschein] (8)
{ Posture [Greek: keisthai] (9)
{ Habit [Greek: echein] (10)
Taking a particular thing or individual, as 'Socrates,' this is
Substance in the proper sense of the word, and can never be a predicate,
but is the subject of all predicates. We may assert of him (1) Substance
in the secondary sense (species or genus) that he is a man or an animal;
(2) Quantity, of such a height or weight; (3) Quality, fair or dark; (4)
Relation, shorter or taller than Xanthippe; (5) Where, at Athens; (6)
When, two thousand and odd years ago; (7) Action, that he questions or
pleads; (8) Passion, that he is answered or condemned; (9) Posture, that
he sits or stands; (10) Habit, that he is clothed or armed.
Thus illustrated (_Categoriae_: c. 4), the predicaments seem to be a list
of topics, generally useful for the analysis and description of an
individual, but wanting in the scientific qualities of rational
arrangement, derivation and limitation. Why are there just these heads,
and just so many? It has been suggested that they were determined by
grammatical forms: for Substance is expressed by a substantive;
Quantity, Quality and Relation are adjectival; Where and When,
adverbial; and the remaining four are verbal. It is true that the parts
of speech were not systematically discriminated until some years after
Aristotle's time; but, as they existed, they may have unconsciously
influenced his selection and arrangement of the predicaments. Where a
principle is so obscure one feels glad of any clue to it (_cf._ Grote's
_Aristotle_, c. 3, and Zeller's _Aristotle_, c. 6). But whatever the
origin and original meaning of the predicaments, they were for a long
time regarded as a classification of things; and it is in this sense
that Mill criticises them (_Logic_: Bk. I. c. 3).
If, however, the predicaments are heads of a classification of terms
predicable, we may expect to find some connection with the predicables;
and, in fact, secondary Substances are species and genus; whilst the
remaining nine forms are generally accidents. But, again, we may expect
some agreement between them and the fundamental forms of predication
(_ante_, chap. i. Sec. 5, and chap. ii Sec. 4): Substance, whether as the
foundation of attributes, or as genus and species, implies the
predication of co-inherence, which is one mode of _Co-existence_.
Quantity is predicated as equality (or inequality) a mode of _Likeness_;
and the other mode of _Likeness_ is involved in the predication of
Quality. Relation, indeed, is the abstract of all predication, and ought
not to appear in a list along with special forms of itself. 'Where' is
position, or _Co-existence_ in space; and 'When' is position in time, or
_Succession_. Action and Passion are the most interesting aspect of
_Causation_. Posture and Habit are complex modes of _Co-existence_, but
too specialised to have any philosophic value. Now, I do not pretend
that this is what Aristotle meant and was trying to say: but if
Likeness, Co-existence, Succession and Causation are fundamental forms
of predication, a good mind analysing the fact of predication is likely
to happen upon them in one set of words or another.
By Kant the word 'Category' has been appropriated to the highest forms
of judgment, such as Unity, Reality, Substance, and Cause, under which
the understanding reduces phenomena to order and thereby constitutes
Nature. This change of meaning has not been made without a certain
continuity of thought; for forms of judgment are modes of predication.
But besides altering the lists of categories and greatly improving it,
Kant has brought forward under an old title a doctrine so original and
suggestive that it has extensively influenced the subsequent history of
Philosophy. At the same time, and probably as a result of the vogue of
the Kantian philosophy, the word 'category' has been vulgarised as a
synonym for 'class,' just as 'predicament' long ago passed from
Scholastic Logic into common use as a synonym for 'plight.' A minister
is said to be 'in a predicament,' or to fall under the 'category of
impostors.'