sufficiently high-sounding. This ability to interpret what one reads or hears and discriminate between sense and nonsense is one of the most essential aims of all education, and a person who has not taken the trouble to acquire it ought not to call himself educated.

How to

We must not define a net

When we have found the meaning of a word and come to state it two things are essential: to be precise and to be simple. To be precise is to tell exactly what the word means -—no more and no less; to state the characteristics frame definitions. of an object, in virtue of which the name is applicable, with perfect definiteness. as something made out of string with holes in it, or as something to catch fish w. For a net is not necessarily made out of string or used to catch fish, and things might be made of string and have holes in them, or be used to catch fish, without being nets. In the same way we should not define man as the animal that laughs, for though man may be the only animal that laughs, it is not laughter that makes him man and entitles him to the name. He would remain man if he never laughed again. So, we should not define virtue as the only thing which makes one truly and permanently happy, or acid as that which turns blue litmus paper red; for virtue might still be virtue if it ceased to make us happy, and the word acid would be quite as applicable to various substances if litmus paper had never existed.

To be simple in a definition is to frame it in such a way that it will immediately mean something to the people for whom it is intended. Dr. Johnson defines a net as something reticulated and decussated, with interstices between the intersections; and Herbert Spencer defines evolution as "an integration of matter and concomitant dissipation of motion, during which the matter passes from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, and during which the retained motion undergoes a parallel transformation. These definitions are precise and to the expert they may be simple, but to ordinary people they are not.

Simplicity and precision are difficult to unite, but with patience the union can nearly always be made.

There is an old rule that definitions should be by genus and differentiæ. This means that it is not necessary or desirable to enumerate every single attribute of the things denoted by the name defined. It is sufficient to tell what class they belong to and how they differ from other members of that class. If we are defining the word 'bloodhound' we should say that bloodhounds are a certain specified kind of dog. It is not necessary to say that they are living things, belonging to the animal kingdom, and possessed of a backbone, mouth, eyes, ears, teeth, and paws. These attributes and a hundred others are all implied by the generic term 'dog'.

To define a term by itself or by some other equally obscure word from the same root, e.g., a preacher is one who preaches', is practically the same as not to define it at all. It adds neither precision nor simplicity. But if two words from the same root do not indicate precisely the same relations it may be proper to define one by means of the other and some modifying phrase, e.g., 'a preacher is one who preaches by profession', 'a liar is one who tells lies habitually'. Again, we are likely to lose rather than gain in both. precision and simplicity when we define in metaphorical language, as when we say that words are barbed arrows, the soul is life's star, truth is the food of the soul, or the camel is the ship of the desert. The metaphors may be useful, but not as definitions.

Illustrations.

Definitions are usually supplemented by examples, diagrams, or other illustrations. These do not make the definition any more accurate, for they give only one case out of many that fall within it, and unless some explanation is added, they do not show exactly where the dividing/ line is. But they do make the definition easier to understand, because they turn one's attention in the right direction. When we know some of the things which a boundary is intended to include we are better prepared to learn precisely

where that boundary is.

Because examples give this kind of preparation it is often wise to put some of them before the

formal definition.

The illustration chosen should be typical. If we try to prepare for the definition of virtue by an example, we should choose some act or character that is recognized as virtuous by everybody; something well within the class, and, if possible, something of which virtue is the most striking feature. To prepare for the definition of a fish we should not draw an eel. It looks too much like a snake. After the definition is given, however, and its general purport is understood it is often wise to give an example of something that falls within it and of something else quite like it that falls without, and then explain why it is that the one is included and the other not. one is making a contrast of this sort one might well use an eel to illustrate the difference between a fish and a snake, or a whale to illustrate the difference between a fish and a mammal. The nearer we get to the boundary on any side the easier it is to understand a description of that particular part of it.

When

When an example is not so striking as to be unmistakable we should take pains to make clear in precisely what respect it illustrates. It will not do to say, "The subject of a sentence is the name of the thing spoken about, e.g., John struck James'. We should underline the word 'John', put it in quotation-marks, or indicate in some other way that it is that word that is the subject, and not the real John or the word 'James'. Similarly we cannot explain what a house is by merely handing some one a picture and leaving him to wonder whether the house is the thing in the background 'with windows or the thing in the foreground with ears.

The reason why the common uneducated person does not recognize the importance of understanding the meaning of words precisely is that it is really not very important for his purposes. To play out of doors, to find one's way along the street and notice what people are doing there, to buy clothes

Where

needed most.

or groceries: all these are very concrete performances, and any one can carry them on or tell about them precision is afterwards fairly well without a painstaking choice of words. With the work of school and the first year or two of college the need for a careful examination and selection of words becomes more apparent; and yet only a fair amount of care and skill in the use of words is required to tell about the concrete facts of history and geography, describe the processes involved in a chemical experiment, and even translate concrete statements from a foreign language, without confusion. But when we comé to the abstract sciences, and have to deal, not with the surface of things, but with their deeper relations, the case is very different. The political economist must make sharp distinctions between wealth, capital, and money; the psychologist, between sensation and perception, conception and imagination, illusion, delusion, and hallucination; the student of ethics, between intention and motive, pleasure and satisfaction; the theologian, between wrong and sin, providence and predestination, substance and personality; the lawyer, between torts and crimes, corporations and partnerships, and so on. Here the things under discussion are not visible and tangible, and we cannot explain what we are talking about by merely pointing the finger. It takes much skill to talk or think about them without confusion, and the only way to be sure of doing so is to make absolutely clearcut, precise, and rigid definitions, and keep them in mind throughout the whole discussion. Such definitions are not conventional ornaments at the head of a page, they are necessities.

Although the meaning of every word, and therefore all definition, has reference to things, we do not define things. Names are defined when we tell what they mean; classes may be said to be 'defined' when we point out their boundaries; things may be described in sentences but never defined, for no words can make them any more definite

Caution.

than they are. The question sometimes raised whether we define names or things depends, as Mill has shown, upon the fact that some definitions carry with them the assumption of the thing's existence in the real word (e.g., any definition of cow or horse), while others do not (e.g., a definition of a dragon or of a perfect man). But in each case it is the meaning of the word, not the thing, with which the definition is primarily concerned. To be sure in the former case we

can prove a definition to be wrong by showing that it does not agree with the thing; but that is because the name stands for the thing, and if the definition does not agree with the thing it cannot correctly explain the name.

In the following chapters it will be necessary to define a considerable number of logical terms. The definitions given were made with care, but doubtless some of them are incorrect. Every reader is urged to make out as well as he can from the explanations, the illustrations, and the definitions themselves exactly what each one of them was intended to express, and then go back and see whether it really did express it or not, and if not why not. This will help him to understand the book and-what is far more important-it will give him good general practice in the accurate interpretation and use of words. To increase the opportunities for this practice there are among the exercises at the back of the book a large number of definitions of these same logical terms which are incorrect, and the reader is advised to go over as many of them as possible and state clearly and exactly what is wrong with each. This he will find much harder than to merely score them out and put correct ones in their places; but the practice is correspondingly better.