Page images

mind think of a strong and very useful metal, but does not tell us anything about it, or compare it with any thing else. The words sun, Jupiter, Sirius, St Paul's Cathedral, are also terms which call up into the mind certain well-known objects, which dwell in our recollection even when they are not present to our senses. In fact, the use of a term, such as those given as examples, is merely as a substitute for the exhibition of the actual things named.

Judgment is a different action of mind, and consists in comparing together two notions or ideas of objects derived from simple apprehension, so as to ascertain whether they agree or differ. It is evident, therefore, that we cannot judge or compare unless we are conscious of two things or have the notions of two things in the mind at the same time. Thus if I compare Jupiter and Sirius I first simply apprehend each of them ;. but bringing them into comparison I observe that they agree in being small, bright, shining bodies, which rise and set and move round the heavens with apparently equal speed. By minute examination, however, I notice that Sirius gives a twinkling or intermittent light, whereas Jupiter shines steadily. More prolonged observation shews that Jupiter and Sirius do not really move with equal and regular speed, but that the former changes its position upon the heavens from night to night in no very simple

If the comparison be extended to others of the heavenly bodies which are apprehended or seen at the same time, I shall find that there are a multitude of stars which agree with Sirius in giving a twinkling light and in remaining perfectly fixed in relative position to each other, whereas two or three other bodies may be seen which resemble Jupiter in giving a steady light, and also in changing their place from night to night among the fixed stars. I have now by the action of judgment formed in my mind the general notion of fixed stars, by


bringing together mentally a number of objects which agree ; while from several other objects I have formed the general notion of planets. Comparing the two general notions together, I find that they do not possess the same qualities or appearances, which I state in the proposition, “ Planets are not fixed stårs."

I have introduced the expression "General Notion” as if the reader were fully acquainted with it. But though philosophers have for more than two thousand years constantly used the expressions, general notion, idea, conception, concept, &c., they have never succeeded in agreeing exactly as to the meaning of the terms. One class of philosophers called Nominalists say that it is all a matter of names, and that when we join together Jupiter, Mars, Saturn, Venus, &c., and call them planets, the common name is the bond between them in our minds. Others, called Realists, have asserted that besides these particular planets there really is something which combines the properties common to them all without any of the differences of size, colour, or motion which distinguish them. Every one allows in the present day however that nothing can physically exist corresponding to a general notion, because it must exist here or there, of this size or of that size, and therefore it would be one particular planet, and not any planet whatever. The Nominalists, too, seem equally wrong, because language, to be of any use, must denote something, and must correspond, as we have seen, to acts of mind. If then proper names raise up in our minds the images of particular things, like the sun, Jupiter, &c., general names should raise up general notions.

The true opinion seems to be that of the philosophers called Conceptualists, who say that the general notion is the knowledge in the mind of the common properties or resemblances of the things embraced under

the notion. Thus the notion planet really means the consciousness in anybody's mind that there are certain heavenly bodies which agree in giving a steady light and in moving about the heavens differently from the fixed stars. It should be added, however, that there are many, including Sir W. Hamilton, who would be counted as Nominalists and who yet hold that with the general name is associated a consciousness of the resemblance existing between the things denoted by it. Between this form of the doctrine and conceptualism it is not easy to draw a precise distinction, and the subject is of too debatable a character to be pursued in this work.

It will appear in the course of these lessons that the whole of logic and the whole of any science consists in so arranging the individual things we meet in general notions or classes, and in giving them appropriate general namés or terms, that our knowledge of them may be made as simple and general as possible. Every general notion that is properly formed admits of the statement of general laws or truths; thus of the planets we may affirm that they move in elliptic orbits round the sun from west to east; that they shine with the reflected light of the sun; and so on. Of the fixed stars we may affirm that they shine with their own proper light; that they are incomparably more distant than the planets; and so on. The whole of reasoning will be found to arise from this faculty of judgment, which enables us to discover and affirm that a large number of objects have similar properties, so that whatever is known of some may be inferred and asserted of others.

It is in the application of such knowledge that we employ the third act of mind called discourse or reasoning, by which from certain judgments we are enabled, without any new reference to the real objects, to form a new judgment. If we know that iron comes under the

general notion of metal, and that this notion comes under the still wider notion of element, then without further examination of iron we know that it is a simple unde, composable substance called by chemists an element. Or if from one source of information we learn that Neptune is a planet, and from another that planets move in elliptic orbits, we can join these two portions of knowledge together in the mind, so as to elicit the truth that Neptune moves in an elliptic orbit.

Reasoning or Discourse, then, may be defined as the progress of the mind from one or more given propositions to a proposition different from those given. Those propositions from which we argue are called Premises, and that which is drawn from them is called the Conclusion. The latter is said to follow, to be concluded, inferred or collected from them; and the premises are so called because they are put forward or at the beginning (Latin præ, before, and mitto, I send or put). The essence of the process consists in gathering the truth that is contained in the premises when joined together, and carrying it with us into the conclusion, where it is embodied in a new proposition or assertion. We extract out of the premises all the information which is useful for the purpose in view—and this is the whole which reasoning accomplishes.

I have now pointed out the three parts of logical doctrine, Terms, Propositions, and Reasoning or Syllogism, into which the subject is conveniently divided. To the consideration of these parts we shall proceed. But it may be mentioned that a fourth part has often been added called Method, which is concerned with the ar. rangement of the parts of any composition.

It is sometimes said that what proposition is to term, and what syllogism is to proposition, such is method to syllogism, and that a fourth division is necessary to com

plete the doctrine of Logic. It is at any rate certain however that this fourth part is much inferior in importance and distinctness to the preceding three; and all that will be said of it is to be found in Lesson XXIV.



It has been explained in the preceding lesson that every assertion or statement expresses the agreement or difference of two things, or of two general notions. In putting the assertion or statement into words, we must accordingly have words suitable for drawing the attention of the mind to the things which are compared, as well as words indicating the result of the comparison, that is to say, the fact whether they agree or differ. The words by which we point out the things or classes of things in question are called Terms, and the words denoting the comparison are said to form the Copula. Hence a complete assertion or statement consists of two terms and a copula, and when thus expressed it forms a Propositior. Thus in the proposition “Dictionaries are useful books,” the two terms are dictionaries and useful books; the copula is the verb are, and expresses a certain agreement of the class dictionaries with the class of useful books consisting in the fact that the class of dictionaries forms part of the class of useful books. In this case each term consists of only one or two words, but any number of words may be required to describe the notions or classes com

« PreviousContinue »