80

GENERAL VIEW, AND BASIS OF SCIENTIFIC RESEARCH.

• Ab

to which they are related by the idea of difference. solute' terms cannot be properly used in cases of degree. A relative' term represents an idea which cannot be thought of alone, but only in relation to some other idea; thus the term 'heavy' can only be thought of in relation to ‘less heavy' or 'light;' that which is 'bright' can only be thought of in connection with that which is less bright' or 'dull.' Relative terms are incommensurable, and have often no real counterpart in nature. Correlative terms are those belonging to the respective relative

ones.

The chief division of terms for scientific purposes is into general and singular. A 'general' term is one which may be used to denote any one of an indefinite number of similar ideas or things; as the term 'gas' may be applied either to hydrogen, nitrogen, oxygen, chlorine, &c., or to any other substance possessing the general properties of a gas. A singular' or 'individual' term is one which, so long as it is employed only in exactly the same meaning, can only represent a single idea or thing; and, unlike a general term, it has a different meaning in every different case; and again, if it is divided, the parts cannot be properly called by the same name as the whole. General ideas and terms represent qualities and properties, which have no existence independent of the class of objects in which they are found; but singular ideas and terms represent individual and separately existing objects. A general term must not be confounded with a collective one. Whilst a general term is the name of a number of objects, but of each of them separately, a 'collective' term is that of a collection of objects combined together in one whole. When we generalise, we form a collective term. Some terms are both general and collective.

A general term is, in logical phraseology, said to

MEANINGS OF GENERAL TERMS.

6

81

possess a greater extension' of meaning than a singular or individual one, because it includes a greater number of objects; and a singular term is said to have a greater intension' of meaning, because it includes a larger number of marks. For instance, the term 'element' has a fuller extension of meaning than the term 'metal,' because it includes not only the whole of the metals, but also other elements; but it has less intension of meaning, because a metal has all the properties of an element, besides some others which show it to be a metal. In a series of terms, arranged in order from the most singular to the most general, usually the two kinds of meaning vary inversely, i.e. the meaning in intension decreases as that in extension increases. Usually the greater the number of qualities, the less the number of individuals; therefore, the one being given, the other can be inferred.

General terms and ideas are obscure, and difficult to conceive, because the existences they represent are of an abstruse character, and can only excite a conscious degree of mental action by means of the intellect; singular ones are more easy to apprehend, because the objects they indicate act more directly and strongly upon our senses and mental powers. General terms and ideas may also be said to have greater profundity of meaning, whilst individual ones are more full of superficial and easily perceived detail.

General terms and ideas embrace a greater amount of knowledge than individual and singular ones; and when they are formed into propositions, a larger amount of knowledge can be extracted from them by means of analysis and inference. They also require more study in order to enable us to understand them. To apprehend the meaning of the word metal,' we must, to some extent, know the essential and abstruse qualities of metallic substances;

G

?

?

but to define that of the word 'copper,' we require only to know the characteristic marks of that body.

An abstract' term is usually considered to be the name of a property, quality, or attribute, considered apart, or abstracted in thought from the object to which it applies, or in which it resides, and from which it cannot usually be separated. Thus weight, magnetism, ductility, brittleness are abstract. When we define, we form an abstract term. By a 'concrete' term is meant the name of a thing in which the abstract quality exists; such, for instance, as the terms platinum, iron, copper, glass, &c., in which the properties of weight, magnetism, ductility, and brittleness respectively reside. Many concrete terms have corresponding abstract ones, but some have not; and the two kinds are often confounded.1 All kinds of substances are capable of separate existence, but their attributes, qualities, properties, and forces are incapable of separate existence, and can only be separated in thought by means of analysis and abstraction.

CHAPTER VII.

ON FACTS AND PROPOSITIONS IN SCIENCE.

A FACT is a truth; the simplest ideas are not truths; for instance, that of iron or of magnetism is not a truth. A fact or truth requires a judgment or proposition by which to express it, such as copper is red,' iron is magnetic,' &c. Contact with nature, through the medium of

1

6

1 A very valuable chapter on 'Scientific Terms and the Language of Science' may be found in Whewell's Philosophy of the Inductive Sciences, vol. i. p. 48, also book viii. p. 449.

SCIENTIFIC FACTS AND PROPOSITIONS.

83

our senses and perceptive powers, furnishes us with a knowledge of existences and facts. The comparison of those facts, and reasoning upon them, supply us with general truths; and a similar treatment of those truths, combined in various ways, yields us knowledge of the still greater principles of science. Study of facts and general truths, and reasoning upon them, also supply us with new hypotheses. All great discoveries depend upon the combination of exact facts with clear ideas.'1

6

Facts are the foundation of all our scientific knowledge, and of all the practical applications of it, and consequently of all the civilisation and human progress resulting from it. Facts are indestructible, and truly said to be stubborn things.' A single fact may overturn the boldest theory. We are utterly unable to alter the truths of science; the facts and laws of nature are the same for all men.

6

Every fact in science includes very much more latent meaning than appears on a superficial examination of it, and frequently involves the operation of many laws. The statement That is an animal' implicitly includes the ideas of all the physical, chemical, and vital powers, and all the laws of their action in animal life. The facts of nature are often very different from our ideas of them, because we perceive their superficial features only, those which strike our senses; and these constitute only a minute proportion of the entire truth the facts implicitly contain. In ancient times a rusting piece of iron was a rusting piece of iron and nothing more; but to the modern chemist it is a case of combustion, electrical action, and many other changes.

Facts are crude knowledge, and constitute the raw

1 Whewell, History of the Inductive Sciences, 3rd edit. vol. iii. p. 147.

A

material of science. They may be divided into generalised and empirical. Generalised facts are those which have been partly digested, and been reduced to class and order, and are frequently capable of being explained by some known law or principle. Empirical facts are those which are undigested, and which we cannot as yet explain or refer to any known cause. An immense number of facts remain in an empirical state ready for the discovery of laws to explain them; for instance, why is copper ductile, lead soft, steel elastic, glass brittle and transparent? &c. The great bulk of the facts relating to those properties of bodies which depend upon molecular structure, are still largely empirical for want of knowledge of the principles of that structure by which to explain them. Empirical facts (and sometimes even generalised ones) are often comparatively useless for the purposes of science until we can draw general inferences from them. They are, however, often of the very greatest practical use in daily life, arts, manufactures, making experiments, &c.

As facts are the original source of all kinds of scientific knowledge, they are as varied as that knowledge, and may therefore be classed under a great variety of headings, such as qualitative and quantitative, the names of various. sciences, the different forces of nature, the numerous elementary and compound substances, &c., as may be seen. in the various text-books of science.

Different empirical facts possess widely different degrees of intrinsic importance, because they contain a greater or less amount of potential truth. General statements are the concentrated essence of knowledge. Different facts also possess different degrees of intrinsic value. For instance, an anomalous fact may be an instance of an unknown and great general law, and thus prove extremely valuable by leading to the discovery of a whole