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plant, because the classes are often defined by the form of minute parts of the seed, the arrangement of the seedvessel, and other parts which it is usually difficult or sometimes impossible to examine. Accordingly botanists usually arrange their genera and species in the order of the natural system, but contrive a sort of key or artificial arrangement, in which the most simple and apparent characters, often called characteristics, are employed for the discrimination of the plants. The best arrangement of this kind as regards British plants is to be found in Bentham's British Flora. In reality the celebrated Linnæan arrangement of plants was intended by its author to serve in this way. Linnæus was too profound a philosopher to suppose that the numbers of stamens and pistils usually expressed the real relationships of plants. Many of his classes were really natural classes, but the stamens and pistils were selected as the general guide to the classes and orders, as being very plain and evident marks.
Closely connected with the process of classification is that of abstraction. To abstract is to separate the qualities common to all individuals of a group from the peculiarities of each individual. The notion “ triangle ” is the result of abstraction in so far as we can reason concerning triangles, without any regard to the particular size or shape of any one triangle. Al classification implies abstraction, for in framing and defining the class I must separate the common qualities from the peculiarities. When I abstract, too, I form a general conception, or one which, generally speaking, embraces many objects. If, indeed, the quality abstracted is a peculiar property of the class, or one which belongs to the whole and not to any other objects, I may not increase the extent of the notion, so that Mr Herbert Spencer is, perhaps, right in holding that we can abstract without generalizing. We
often use this word generalization, and the process may be defined as inferring of a whole class what we know only of a part. Whenever we regard the qualities of a thing as not confined to that thing only but as extended to other objects; when, in fact, we consider a thing only as a member of a class, we are said to generalize. If, after studying the properties of the circle, we proceed to those of the ellipse, parabola and hyperbola, it is soon found that the circle is only one case of a whole class of curves called the conic sections, corresponding to equations of the second degree; and I generalize when I regard certain of the properties of the circle as shared by many other curves.
Dr Whewell added to the superabundance of terms to express the same processes when he introduced the expression Colligation of facts. Whenever two things are found to have similar properties so as to be placed in the same class they may be said to be connected together. We connect together the places of a planet as it moves round the sun, when we conceive them as points upon a common ellipse. Whenever we thus join together previously disconnected facts, by a suitable general notion or hypothesis, we are said to colligate them. Dr Whewell adds that the general conceptions employed must be (1) clear, and (2) appropriate ; but it may well be questioned whether there is anything really different in these processes from the general process of natural classification which we have considered.
REQUISITES OF A PHILOSOPHICAL
AMONG the subsidiary processes requisite to the successful prosecution of inductive reasoning must be placed the construction of a suitable language. It is in fact impossible to over-estimate the importance of an accurate and copious language in any science; and the study of things would be almost useless without names to denote those things and record our observations concerning them.
It is easily apparent, indeed, that language serves three distinct and almost independent purposes :
1. As a means of communication.
3. As an instrument of record and reference. In its first origin language was used chiefly if not exclusively for the first purpose. Savage tribes exist in great numbers at the present day who seem to accumulate no knowledge. We may even say that the lower animals often possess some means of communication by sounds or natural signs which constitute language in the first sense, though they are incapable of reasoning by general notions.
Some philosophers have held that it is impossible to carry on reasoning without the use of language. The true nominalist went so far as to say that there are no such things as general notions, and that general names therefore constitute all that is general in science and
reasoning. Though this is no doubt false (see p. 13), it must nevertheless be allowed that unless general ideas were fixed and represented by words, we could never attain to sustained thought such as we at present enjoy. The use of language in the second purpose is doubtless indispensable in a practical point of view, and reasoning may almost be considered identical with the correct use of words. When language is used solely to assist reasoning there is no need that the meaning of each word should be fixed; we might use names, as the letters x, y, 2, a, b, c, &c., are used in algebra to denote any quantity that happens to occur in a problem. All that is requisite is never to confuse the meaning attributed to a word in one argument with the different meaning attributed in another argument. Algebra may, in fact, be said to consist of a language of a very perfect kind adapted to the second purpose only, and capable of leading a person to the solution of a problem in a symbolical or mechanical
Language, as it is furnished to us ready made by the habitual growth of centuries, is capable of fulfilling all three purposes, though by no means in a perfect manner. As words possess a more or less fixed customary meaning we can not only reason by their aid, but communicate our thoughts or record them ; and it is in this last respect we have now to treat the subject.
The multitude of facts required for the establishment of a science could not be retained in the memory with sufficient accuracy. Hence an indispensable subsidiary of induction is the means of describing and recording our observations. Thus only can knowledge he accumulated, so that each observer shall start with the advantage of knowing what has been previously recorded and proved. It will be necessary then to consider the mode in which language serves for the registration of facts, and to investi
gate the requisite qualities of a philosophical language suitable to the needs of science.
As an instrument of record language must evidently possess two principal requisites :
1. Precision or definiteness of meaning,
2. Completeness. A name is worse than useless unless, when used to record a fact, it enables us to ascertain what was the nature of the fact recorded. Accuracy and precision is then a more important quality of language than abundance. The want of an appropriate word will seldom give rise to actual error and fallacy; it will merely oblige us to employ a circumlocutory phrase or else leave the fact unrecorded. But it is a self-evident convenience that whenever a thing, notion, or quality has often to be referred to there should be a name appropriated to the purpose, and there ought only to be one name. consider in succession what nrust be the character of a precise and complete language.
It may not previously have struck the reader, but it is certainly true, that description is impossible without the assertion of resemblance between the fact described and some other fact. We can only describe a thing by giving it a name; but how can we learn the meaning of that name? If we describe the name by other names we only have more names of which the meanings are required. We must ultimately learn the meanings, not from names but from things which bear those names. were ignorant of the meaning of blue he could not be informed but by reference to something that excited in him the sensation of blueness, and had he been blind from birth he could not acquire any notion of what blueness
There are indeed a number of words so familiar to us from childhood that we cannot tell when or how we learnt their meanings, though it must have been by refer