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LOGIC.

CHAPTER I.

INTRODUCTION.

The business of Logic is to help us to think clearly and objectively, express ourselves plainly and accurately, reason correctly, and estimate aright the statements and arguments of others.

We cannot fully understand what is meant by the statement that logic helps us to think clearly unless we distinguish carefully between two kinds of thinking. The first kind makes some statement or asks Two kinds of

thinking some question; the second consists in a mere play of mental images, such as takes place when we follow quite passively the successive notes of a piece of music, hearing each as it passes but doing nothing more, or when the music runs through our head afterwards in the same way, or when half-dozing we watch the pictures that float before us, or when in the same passive way we feel yet do not note the sensations that come from our limbs as we walk or row or take some other such mechanical exercise. But just as soon as we recognize that the music is or is not beautiful, that one note is following another, that some one is playing, or that we are hearing, feeling, or imagining something, then we get back for the moment at least to the first kind of thinking; for to the mere passive images

and propo

we have added something else and there is now an active affirmation or denial.

The second kind of thinking—that which consists in the mere play of sensations or images---serves no purpose beyond the pleasure or recreation of the thinker; and logic has nothing to do with it. Consequently, when we speak of clear thinking we do not refer to the vividness or continuity of such passive images, but rather to the definiteness and consistency of active affirmations, denials, or questions.

When we affirm or deny anything we are said to form a belief, to come to a conclusion, or to pass a judgment; and

the sentence in which the judgment is expressed Judgments

is called a proposition. Propositions can thus sitions.

be defined as sentences expressing judgments. According to this definition interrogative sentences are not propositions, for a question implies the absence of a judgment. On the other hand negative sentences are propositions; for it is quite as much an act of judging to deny that something is the case, e.g., to say or think · The day is not hot', as to affirm it-to say or think. The day is hot ’. There is thus a vast difference between saying that a thing is not so and not saying that it is so, in spite of the fact that we often say “I do not think so 'when we mean “I think not'.

Judgments always have reference to something other than themselves. Like the eye which always looks outward and never sees itself, they are always concerned with some object or other which lies beyond them, and never with themselves. This is most important. Perhaps it can be made clear by an illustration from grammar.

When I

say

“The word 'good' is an adjective”, I am speaking of that word as it occurred somewhere else; for as I use it here it is a noun. Words never refer to themselves, but to something else which they name or' mean’. The same is true of judgments. When I say The house is on fire ”, I do not mean to state anything about myself or about my judgment with

or

reference to the house. I do not even mean to say that I judge that the house is on fire. I do judge it; and the statement expresses my judgment. But to express a judgment is to tell something about the object thought about or judged of—in this case the house—not about the thought or judgment itself, or the person who passes it, or the words in which it is expressed. When we wish to see our own eyes we do not look at them directly, but at their image in a mirror. So when we wish to know our own thought we must get a new thought with the thought in question as its object, e.g., 'I thought that the house was on fire', 'I recognized that the house was on fire '. In these propositions I am talking about my own thought or judgment; in the former I was not. But even here the thought of which I am speaking is not the thought that I am expressing, for I am speaking of the past thought and expressing the present thought about it.

That about which a judgment is passed, i.e., that about which something is asserted (affirmed or denied), is called the Subject or Object of our thought. If it is a real thing or person, it is also called the subject of the relations that are affirmed of it, and the word used to point it out is usually the subject of the sentence or proposition in which the judgment is expressed. Thus, in the example just given, the real house is the subject of the state we call being on fire, for it is the house—not something else—that is blazing; the real house is the subject of the judgment, for it is the real house that I am thinking and speaking about; but it is the word ‘house' that is the subject of the sentence. It is not the word · house’ that is on fire or of which I am thinking or speaking, and it is not the real house that is part of a sentence. Thus the subject of a sentence is not that about which something is stated in the sentence, but it is the name of that about which something is stated.

We should never confuse these three different meanings of the word Subject—what we are thinking about, or the

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