An object being given by perception we develop our knowledge of it,
first by narrowing our focus of attention so as to perceive parts and
single attributes of the object; next by widening our attention so as
to include several objects in one view. The first process is Analysis
or Abstraction; it informs us what attributes co-inhere to constitute
the object. The second is Synthesis or Grouping, by which we learn
the relations of one thing to others. These operations comprise all we
know about a thing, for it can have no attributes which are not either
internal or external.
Practical analysis means cutting a thing to pieces or dissolving it,
and this has a certain value because it multiplies objects. But it
does not increase our knowledge of the first thing. On the contrary,
by destroying a thing we render a knowledge of it impossible. The
analysis which gives knowledge is Metaphysical Abstraction--an
attention concentrated on the parts of a thing without destroying
their connection with the other inherent parts. The metaphysical
elements may be quite different from the mechanically divisible parts.
They are generally a species of things which could not exist alone,
such as red, blue, straight, curved, square, round, acid, sweet,
insipid, fragrant, sharp, hot, heavy, dull, loud, bright, and a
multitude of properties of that abstract kind.
For many of these--at least for the description of them--a comparison
of two or more things is essential. A sound is heard to be loud by
comparison with another which is low or soft; a knife is known to
be blunt by experience of another more sharp, or the same knife in
a sharper condition. But comparison does not alter the essential
character of abstract attention--it serves merely as an incitement to
it. Difference between qualities otherwise alike whets our attention
to a finer discrimination.
The properties recognised by each sense are easily distinguished in
the bulk from those of another sense. Colour is distinct from Figure
in a more marked degree than red from blue or square from circular.
Fine degrees of Sound may be difficult to discriminate, but not the
difference between a sound and a smell or a taste.
Still broader contrasts give rise to an artificial but sometimes
useful kind of attribution--the negative. When we do not know much
concerning the positive characteristics of a thing, it is something
to know that it has _not_ this or that property. What Thought is,
positively, few people know, but they are able to say (with a little
prompting) that it is un-extended, im-material, im-ponderable, and so
forth. This comparison re-acts on the thing better known, and so we
call visual objects 'extended' from their dissimilarity to thoughts.
But for that there would have been no occasion to notice the abstract
extension of visual objects. The term 'visual object' would have
tacitly included extension. There must be great and general ignorance
of a thing to excuse the negative attribution: it is not allowable
to speak of plants as non-metals, or sheep as non-horses, but a large
class of animals is called in-vertebrate. In this case the negative
property serves to bar a possible inference that all animals are
vertebrate, since those we know best are so.
The judgment in this category is a consciousness of the attributes
making up a thing, or so much of it as interests us. 'Cleopatra's
Needle is an obelisk of granite, about sixty-eight feet high, and is
carved with hieroglyphics.' If we go on to say that it stands on the
Thames Embankment, we shift into the category of association. The
relation of an object to its place is different from that of one
inherent attribute of the object to another, or to the whole.
The properties of a general idea are defined in this category. The
synthesis is natural or noumenal, the artificiality of the idea
consisting merely in the omission of some of the concrete properties.
'Garden rhubarb [in general] has broadly cordate leaves, strongly
veined beneath; the footstalks are long, thick, and fleshy, with a
channel above; its growth is exceedingly rapid.' These are properties
inherent in a unity not of our making. The botanist changes into the
category of sequence when he says, 'the stalks are used for tarts and
made into jam.'
In a complicated object or general idea some of the judgments we treat
as inherent may be inferences in other categories used subordinately.
'The ancient Persians had remarkably thin and weak skulls. They were
good horsemen and archers, courageous and spirited in battle. They
wore a tunic and trousers of leather.... They were quick and
lively, keen-witted, capable of repartee, ingenious, and--for
Orientals--far-sighted. They had fancy and imagination, a relish for
poetry and art, and they were not without a certain power of political
combination.' Some of these properties might have been perceived
objectively, but not the possession of fancy and imagination, which
could only be known by inference in causation--here used to complete
a coherent unity. The historian employs causation as a principal
category when he tells us that 'their bards did not touch the chords
which rouse what is noblest and highest in our nature.' The thought
implied in touching chords--the notion of will directing action--is
a different judgment from the perception of an inherent permanent
attribute.
The argument in this category consists in ideally completing an
imperfect object by comparison with a similar object, or the idea of a
similar object. Suppose we have studied thoroughly one or more rhubarb
plants, and then see a plant with broadly cordate leaves, footstalks
long, thick, and fleshy, and having a channel above. In the time at
our disposal we cannot ascertain if its growth is exceedingly rapid,
but we are justified in inferring that it is, and that the plant
we are examining is in all other respects rhubarb. If the Egyptian
obelisks we have seen were sculptured with hieroglyphics throughout
their length, and we see an obelisk part of which is underground, it
is a rational inference that that part also is sculptured.
We have proved that certain samples of aluminium have a specific
gravity of 2·6, and then see a metal--of specific gravity
unknown--which has all the other properties of aluminium: we may
confidently infer that this metal also would, if tested, show a
specific gravity of 2·6.
For purposes of reason it may be necessary to compare things that
cannot be brought physically together. When this happens we generally
compare them in _idea_, or the idea of one with the other as object.
When great accuracy is required and the idea--which is always rather
vague--cannot be relied on, we have recourse to mediate comparison.
_Standards_ are employed. These are manageable or portable objects
with which principal things are separately compared by way of
effecting indirectly a comparison between them. Standards can only
mediate comparisons between _abstract_ properties, for if they
contained all the concrete properties of the compared objects they
would, by supposition, be as unmanageable as the latter. We have
standards for length in rules, scales, tapes, chains; the balance is
a standard for weight. There are also scales for pitch of sound,
varieties of colour, degree of light, heat, atmospheric pressure, and
probably some others for special purposes.
Indirect comparison is not in itself inference; or if inference it is
subordinate and preparatory to some more important conclusion. A coin
is weighed and concluded to be _light_, but this is only a datum in
determining the more important question whether it is a forged coin or
not.