241

PREPARATORY LOGIC.

The intention of the following pages is, to furnish the young student with an explanation of the nature of Logic, and of its principal Terms and Rules, by which he may be prepared, at a subsequent period, to enter with advantage upon the regular study of this branch of Education.

Preparatory Logic.

1. " Logic," says Dr. Whately, "in the most extensive sense which the name can, with propriety, be made to bear, may be considered as the Science, and also as the Art, of Reasoning. It investigates the Principles on which argumentation is conducted, and furnishes Rules to secure the mind from error in its deductions. Its most appropriate office, however, is that of instituting an analysis of the process of the mind in Reasoning; and, in this point of view, it is, as has been stated, strictly a Science; while, considered in reference to the practical Rules above mentioned, it may be called the Art of Reasoning."

"On the Utility of Logic," continues the Doctor, "many writers have said much with which I cannot coincide, and which has tended to bring the study into unmerited disrepute. By representing Logic as furnishing the sole instrument for the discovery of truth on all subjects, and as teaching the use of the intellectual faculties in general, they raised expectations which could not be realized, and which naturally led to a re-action. The whole system, whose unfounded pretensions had been thus blazoned forth, has come to be commonly regarded as utterly futile and empty; like several of our most valuable medicines, which, when first introduced, were proclaimed, each as a panacea, infallible in the most opposite disorders; and which, consequently, in many instances, fell, for a time, into total disuse; though, after a long interval, they were established in their just estimation, and employed conformably to their real properties.

"To explain fully the utility of Logic, is what can be done only in the course of an explanation of the system itself. One preliminary observation only it may be worth while to offer in this place. If it were inquired, what is regarded as the most appropriate intellectual occupation of MAN as man, what would be the answer? The Statesman is engaged with political affairs; the Soldier with military; the Mathematician with the properties of numbers and magnitudes; the Merchant with commercial concerns, &c., but in what are all and each of these employed?-employed, I mean, as men; for there are many modes of exercise of the faculties, mental as well as bodily, which are, in a great measure, common to us with the lower animals. Evidently in Reasoning. They are all occupied in deducing, well or ill, Conclusions from Premises; each concerning the Subject of his own particular business. If, therefore, it be found that the process going on daily, in each of so many different minds, is, in any respect, the same, and if the Principles on which it is conducted can be reduced to a regular system, and if Rules can be deduced from that System for the better conducting of the process, then, it can hardly be denied that such a System and such Rules must be especially worthy the attention, not of the members of this or that profession merely, but of every one who is desirous of possessing a cultivated mind. To understand the theory of that which is the appropriate intellectual occupa

Y

tion of Man in general, and to learn to do that well, which every one will and must do, whether well or ill, may surely be considered as an essential part of a liberal education."

2. The Rules of Logic have nothing to do with the truth or falsity of the premises, except, of course, when they are the conclusions of former arguments; but merely teach us to decide, not whether the Premises are fairly laid down, but whether the Conclusion follows fairly from the Premises or not. Whether the Premises may fairly be assumed or not, is a point which cannot be decided without a competent knowledge of the nature of the subject itself.

For example, in Natural Philosophy, in which the circumstances that, in any case, affect the result, can be clearly ascertained, a single instance is often accounted a sufficient Induction; thus, having once ascertained that an individual magnet will attract Iron, we are authorized to conclude that this property is universal. But, in the affairs of human life, on the other hand, a much fuller induction is required, than in the former example. In short, the degree of evidence for any proposition which we originally assume as a premiss, whether it is the expressed or suppressed one, is not to be learned from Logic, nor, indeed, from any one distinct Science; but is the province of whatever Science furnishes the matter of your argument. None but a Politician can judge rightly of the degree of evidence of a proposition in Politics; a Naturalist, in Natural History, &c.

3. There are four operations of the mind immediately concerned in argument, and in communicating the result to others; 1st, Apprehension; 2nd, Judgment; 3rd, Reasoning; 4th, Method.

1. Apprehension.

1. Apprehension is the notion or conception of any object in the mind, and is analogous to the perception of the senses. It is either Incomplex or Complex. Incomplex Apprehension is of one object, or of several without any relation being perceived between them, as, of " a man, "a horse," "cards." Complex Apprehension is of several with such a relation, as, of "a man on horseback," 66 a pack of cards."

"

2. Perception is that act by which we become conscious of any thing.

As, when we feel hunger, thirst, or cold; when we see a horse, a tree, or a man; when we hear a human voice, or music, we are conscious of these things; this is called Perception. If we study, meditate, wish, or fear, we are conscious of these inward acts also, and our minds perceive their own thoughts, wishes, fears, &c.

3. An Idea is the picture, notion, or conception, of some external objects, formed in the mind through the medium of the five senses, sight, hearing, taste, touch, smell; or, it is the notion or conception which the mind gains when it attends to its own internal operations. The object of which

the idea is the representation, is called the Archetype of the idea. The sources of knowledge by which the mind is supplied with all its materials for thinking, are two; Sensation and Reflection.

4. Sensation is the source of such original ideas as are conveyed into the mind by impulses made upon the organs of sense; such are the ideas of white, black, yellow, cold, soft, bitter, and all those which are called sensible qualities. We derive all such ideas from external objects.

5. Reflection is the source of those ideas which arise from the attention of the mind to its own internal operations ; such as thinking, doubting, hoping, fearing, &c. These ideas we receive into our understandings as distinctly as we receive ideas from bodies which affect the senses.

6. The ideas with which the mind is thus furnished, are divided into Simple, Complex, and Abstract.

7. A Simple Idea is one uniform idea, which cannot be divided or distinguished by the mind into two or more ideas.

Of this kind are most of our ideas of the qualities of bodies; as, hard, round, smooth, white, cold: all ideas, perhaps, of taste, smell, sound; as, bitter, sweet, loud of the feelings and operations of the mind; as, of desire, willing, judging, thinking, pain, hunger.

8. A Complex Idea contains two or more simple ideas, into which it may be divided; each of which simple ideas may be the subject of consideration.

All our ideas of subtances are complex; as, of animals, vegetables, and the inanimate parts of nature. The idea of a tree, for instance, includes a great variety of subordinate ideas; as, those of wood, stock, roots, branches, vegetable life, shape, leaves, &c.; several of which may be divided into other ideas. All ideas of figures are complex; as, of squares, triangles, cubes: most of the ideas of virtues and vices; as, of justice, fortitude, ingratitude, falsehood.

9. A simple idea cannot be described. In explaining, therefore, a simple idea, we may employ some other word, nearly of the same meaning.

When no synonymous word can be found to express a simple idea, we may mention some object to which it belongs, or some cause which produces it; thus, we may say, redness belongs to a rose; hunger is the pain felt from want of food. But this does not describe hunger; it only makes known what particular pain is meant.

10. A complex idea can be described, because it consists of several simple ideas joined together.

By describing a complex idea is meant, that we can mention the several simple ideas which are included in it, and explain the manner in which they are connected together. Thus, Virtue is the agreement of feelings and actions with the will of God. Design is the relation of the parts of a complex body to the last effect which they are conjoined to produce.

11. Abstract Ideas are those ideas formed by the mind in thinking of some one quality or circumstance belonging to several different things, while it pays no regard to the things themselves, or their other qualities; thus, length, breadth, whiteness, beauty, virtue.

"If several marbles are before us, we merely observe their perfect resemblance to one another. But, if we see together, a marble, a bullet, a ball, a glass bubble, and an orange, we are led to take notice of their similarity in one respect, namely,shape; and, at the same time, to observe their unlikeness in all other respects. We think of them as different things alike in shape. The mind forms a distinct and separate notion of this likeness in shape, and then seeks for a word to represent the notion. The word roundness is used. This is not the name of any one sort of thing, like the word marble; but it is the name of a notion that has been formed after we have taken notice of some one respect in which different objects are alike. Such a notion or idea is called an Abstract Idea; and the name of it is called an Abstract Term. With the help of the name which we have given to this separate notion, we can conveniently think and speak of a particular shape, while we entirely forget the other qualities or appearances of the various objects to which it may belong. This act of the mind, when it thinks of some one quality or circumstance apart from all the other qualities or appearances of the things in which that quality is found, is called Abstraction."

12. The word which we use when we think of a quality, together with the particular thing to which it belongs, is called a Concrete Term; virtuous, good, round, swift, are concrete terms, because they require to be joined to the name of something; as, a virtuous woman, a good man, a round table, a swift horse. But, when the qualities are considered apart from their substances, the terms are called abstract terms; as, virtue, goodness, roundness, swiftness.

2. Judgment.

1. Judgment is comparing together, in the mind, two of the notions or ideas which are the objects of Apprehension, whether complex or incomplex, and pronouncing that they agree or disagree with each other; or, that one of them belongs or does not belong to the other. Judgment, therefore, is either affirmative or negative.

2. Any judgment of the mind concerning two or more things, expressed in words, and declaring that they agree or disagree, is called a proposition. The thing which is spoken of, is called the subject; what we affirm or deny respecting it, is called the predicate; and the word which connects the two ideas, is called the copula.

1. Thus, in the proposition, "Logic is useful;" Logic is the subject, useful, the predicate, and is, the copula. The copula must be either is or is not, or some other tense of the verb to be, either with or without a negative; thus, "The earth is a spheroid;" here, is is the copula. "The earth is not a plane;" here, is not is the copula. All other verbs are resolvable into the verb to be, and a participle or adjective; thus,

"The Romans conquered the Greeks;" here, the word conquered is both copula and presubject copula predicate

dicate; the whole sentence being equivalent to "The Romans were victorious over, predicate

or, the conquerors of, the Greeks."

2. When a negative is connected with the subject, it is generally considered as part of the subject; when connected with the predicate, as part of the predicate; as, "No man is without sin;" here, no man must be considered as the subject. It is not necessary that there should be three separate words to form a proposition. The asserting word or verb may sometimes include the predicate; thus, "Carthage was," means, Carthage was once existing.

3. Propositions are affirmative or negative, universal or particular, absolute or conditional, simple or compound.

4. When the predicate is affirmed of the subject, the proposition is affirmative; when it is denied of the subject, the proposition is negative. "A stone is heavy," is an affirmative; "God is not the author of evil," is a negative proposition. Those propositions, also, in which the negative term properly belongs to the subject, are regarded by logicians as negative propositions. Thus, "No good man is dishonest," is considered as a negative proposition.

5. When the subject of a proposition is a general term, taken in its whole extent, that is, includes every individual comprehended under that name, the proposition is called universal. When the subject is limited to some one or more of the species or individuals included in it, it is called a particular proposition. "No man is perfect," "Every man is mortal," are examples of universal propositions. "Few men are truly good," "Some stones are heavier than iron;" are particular propositions.

6. Propositions are likewise said to be either absolute or conditional. An absolute proposition is one in which we affirm some property to be inseparable from the subject, and, consequently, belonging to it in every case; as, "God is infinitely good;" "Virtue tends to the ultimate happiness of man." But when the predicate can be affirmed of the subject, only upon some consideration distinct from the subject, the proposition is then called conditional; thus, "If a stone be exposed to the rays of the sun, it will contract some degree of heat.'

7. If the proposition has only one subject and one predicate, it is termed a simple proposition; as, "The Lord is omnipotent." If it has two or more subjects or predicates, or both, it is a compound proposition; as, "Learning and virtue are better than riches and power." Here, there are