Classes of Concepts.
In the preceding chapter we have seen the process of conception--of the
forming of concepts. _The idea of a general class of things or qualities
is a concept._ Each concept contains the qualities which are _common to
all_ the individuals composing the class, but not those qualities which
pertain only to the minor classes or the individuals. For instance, the
concept of "bird" will necessarily include the common qualities of
warm-bloodedness, featheredness, wingedness, oviparousness, and
vertebratedness. But it will _not_ include color, special shape, size,
or special features or characteristics of the subfamilies or individuals
composing the great class. The class comprises the individuals and
subclasses composing it; the concept includes the general and common
qualities which _all_ in the class possess. A _percept_ is the mental
image of a particular thing; a _concept_ is the mental idea of the
general qualities of a class of things. A percept arises from the
perception of a sensation; a concept is a purely mental, abstract
creation, whose only existence is in the world of ideas and which has
no corresponding individual object in the world of sense.
There are two general classes of concepts, namely: (1) concrete
concepts, in which the common qualities of a class of things are
combined into one conceptual idea, such as "bird," of which we have
spoken; (2) abstract concepts, in which is combined the idea of some
_quality_ common to a number of things, such as "sweetness" or
"redness." Jevons's well-known rule for terms is an aid in remembering
this classification: "_A concrete term is the name of a thing; an
abstract term is the name of a quality of a thing._"
It is a peculiar fact and rule of concrete concepts that (1) the larger
the class of things embraced in a concept, the smaller are its general
qualities; and (2) the larger the number of general qualities included
in a concept, the smaller the number of individuals embraced by it. For
instance, the term "bird" embraces a great number of individuals--all
the birds that are in existence, in fact, but it has but few general
qualities, as we have seen. On the contrary, the concept "stork" has a
much larger number of general qualities, but embraces far fewer
individuals. Finally, the individual is reached, and we find that it has
more qualities than any class can have; but it is composed of the
smallest possible number of individuals, one. The secret is this: No
two individuals can have as many qualities _in common_ as each has
individually, unless they are precisely alike, which is impossible in
nature.
IMPERFECT CONCEPTS.
It is said that outside of strictly scientific definitions very few
persons agree in their concepts of the same thing. Each has his or her
own concept of the particular thing which he or she expresses by the
same term. A number of persons asked to define a common term like
"love," "religion," "faith," "belief," etc., will give such a variety of
answers as to cause wonderment. As Green says: "My idea or image is mine
alone--the reward of careless observation if imperfect; of attentive,
careful, and varied observation if correct. Between mine and yours a
great gulf is fixed. No man can pass from mine to yours, or from yours
to mine. Neither in any proper sense of the term can mine be conveyed to
you. Words do not convey thoughts; they are not vehicles of thoughts in
any true sense of that term. A word is simply a common symbol which each
associates with his own idea or image."
The reason of the difference in the concepts of several persons is that
very few of our concepts are nearly perfect; the majority of them are
quite imperfect and incomplete. Jevons gives us an idea of this in his
remarks on classification: "Things may seem to be very much like each
other which are not so. Whales, porpoises, seals, and several other
animals live in the sea exactly like a fish; they have a similar shape
and are usually classed among fish. People are said to go whale fishing.
Yet these animals are not really fish at all, but are much more like
dogs and horses and other quadrupeds than they are like fish. They
cannot live entirely under water and breathe the air contained in the
water like fish, but they have to come to the surface at intervals to
take breath. Similarly, we must not class bats with birds because they
fly about, although they have what would be called wings; these wings
are not like those of birds, and, in truth, bats are much more like rats
and mice than they are like birds. Botanists used at one time to
classify plants according to their size, as trees, shrubs, or herbs, but
we now know that a great tree is often more similar in character to a
tiny herb than it is to other great trees. A daisy has little
resemblance to a great Scotch thistle; yet the botanist regards them as
very similar. The lofty growing bamboo is a kind of grass, and the sugar
cane also belongs to the same class with wheat and oats."
It is a matter of importance that clear concepts should be formed
regarding at least the familiar things of life. The list of clear
concepts should be added to from time to time by study, investigation,
and examination. The dictionary should be consulted frequently, and a
term studied until one has a clear meaning of the concept the term seeks
to express. A good encyclopedia (not necessarily an expensive one, in
these days of cheap editions) will also prove very useful in this
respect. As Halleck says: "It must be borne in mind that most of our
concepts are subject to change during our entire life; that at first
they are made only in a tentative way; that experience may show us, at
any time, that they have been erroneously formed, that we have
abstracted too little or too much, made the class too wide or too
narrow, or that here a quality must be added or there one taken away."
It is a good practice to make a memorandum of anything of which you may
hear, but of which you know nothing, and then later to make a brief but
thorough investigation of that thing, by means of the dictionary and
encyclopedia, and of whatever good works may be obtained on the subject,
not leaving it until you feel that you have obtained at least a _clear
idea_ of what the thing really _means_. A half hour each evening devoted
to exercise of this kind will result in a wonderful increase of general
information. We have heard of a man who made a practice of reading a
short article in the encyclopedia every evening, giving preference to
subjects generally classed as familiar. In a year he made a noticeable
advance in general knowledge as well as habits of thought. In five years
he was looked upon by his associates as a man of a remarkably large
field of general information and of more than ordinary intelligence,
which verdict was a just one. As a rule we waste far more time on
worthless fiction than we are willing to devote to a little
self-improvement of this kind. We shrink at the idea of a general course
of instructive reading, little realizing that we can take our study in
small installments and at a very little cost in time or labor.
Our concepts form the material which our intellect uses in its reasoning
processes. No matter how good a reasoner one may be, unless he has a
good supply of general information about the things of which he is
reasoning, he will not make much real headway. We must begin at the
bottom and build a firm foundation upon which the intellectual structure
may be erected. This foundation is composed of _facts_. These facts are
represented by our clear and correct concepts.