Logic for the million; a familiar exposition of the art of reasoning

Preface

I have called this book, Logic foe the Million. By this title, I mean that here the Art of Seasoning is explained in such a way as to be readily understood even by those men and women who have not had the advantage of a literary education.

The imperfection of the existing works on Logic, as means of popular instruction, is thus stated by Mr. Blakey : —

" There seem to be two principal causes which render modern systems of logic both tiresome and comparatively useless; and these are, first, the employment of a vast number of the old scholastic terms and phrases, derived from logicians of former times, which throw over the art such an air of difficulty and perplexity, that the reader, before he has well entered upon the study of his subjeet, is worn out by the mere pressure of uncouth words, and is glad to make his retreat from such an irksome task with all possible expedition. The second cause, and one which is by far the most important, is, that our common books of logic may be said rather to treat of metaphysical systems than to unfold those rules, precepts, and suggestions, which are instrumental in directing the judgment to right conclusions on the various important subjects with which it is necessary that man should be well acquainted. The generality of the books here alluded to, have been founded a 2

VI PKEFACE.

upon the principle, that before we could exercise our reasoning powers with energy and effect, — before we could form right notions, and give method and consistency to our conceptions, — it was absolutely necessary that we should be expert metaphysicians, should be acquainted with all the mental speculations of the day, and intimately and familiarly conversant with the anatomy and physiology of our own minds. But this, I apprehend, is a radical error in our common treatises on logic."

The first cause refers to scholastic logic, the second to metaphysical logic.

The advocates of the scholastic system of logic still contend for the use of a technical language. It has been a great hindrance to popular education, that as soon as any branch of knowledge is exalted into a science, it is surrounded by a number of uncouth words, the understanding of which is more difficult than the understanding of the science. The practice of using hard words to denote common things was ridiculed in "Butler's Hudibras," with reference to the rhetoricians, and the ridicule will apply with equal justice to the scholastic logicians

" For rhetoric, he could not ope' His mouth but out there flew a trope ; And when he happen'd to break off F the middle of his speech, or cough, He 'd hard words ready to show why, And tell what rules he did it by ; Else, when with greatest art he spoke, You 'd think he talk'd like other folk ; For all the rhetorician's rules Teach nothing but to name his tools."

Metaphysical logic consists in the knowledge of the nature of those powers of the mind which are exercised in

PREFACE. Vli

the act of reasoning. This subject is not discussed in the following pages. It does not appear to me that this metaphysical knowledge is at all necessary to the art of reasoning. The analogy between the body and the mind seems to hold good in this case. Dancing is an act of the body. Reasoning is an act of the mind. As it is not necessary to understand the anatomy of the body in order to dance well, so it is not necessary to understand the anatomy of the mind in order to reason well. The study of metaphysical science seems rather to teach the art of doubting than the art of reasoning. By this kind of study Berkeley was led to doubt the existence of matter, and Hume that of mind. " No man," observes Mr. Blakey, " appears more unfit for argumentative discussion, on the common and every-day topics which engage the attention of men of the world, than the profound thinker or the man of mental abstraction. His power of mental analysis is too refined for objects of a formidable and gigantic nature ; and when he comes out into common life to measure his strength with the rustic minds around him, he too often finds, to his great mortification, that he is worsted and driven from the field by the athletic vigour of those who know nothing but what Nature has taught them about the abstract nature of mind or the recondite rules of mental philosophy."

It would be tedious to enumerate all the particulars in which the system of logic described in this work differs from the other systems now before the public. In one respect the difference will be obvious — that is, in the character and number of the illustrations. I have not copied from other logical works trivial and fictitious examples, capable of no practical application. My illustrations have been gathered from authors of established reputation, and are generally upon subjects of great public

VU1 PREFACE.

or private interest. I have taken most of my quotations from the Bible, from books, on political economy, and from newspapers-; others from books referring to the ordinary affairs of life — chiefly to health, education, and conduct. I have not stopped to examine whether I do or do not concur in all the sentiments, they express. I adduce them as illustrations of reasoning ; though I believe they will generally be found. also to be otherwise useful. Some have been selected because they are entertaining; others, because they teach lessons, of still higher importance than even the art of reasoning.

Few alterations have been made, in this edition except in regard to the illustrations. Some of these have been shortened, some transposed, some ■ omitted, and others introduced. Their bearing .as examples of reasoning has occasionally been more clearly exhibited by a change of type, the freer use of italics, and the excision of superfluous sentences, so that the student may not allow the information, the instruction, or the humour of the quotation to render him unmindful of its logical character. For the sake of those who might wish to study the science of logic as well as the art, I have placed in the notes a few references to the philosophical work recently published by Mr. Samuel Bailey on " The Theory of Seasoning." The object of these changes has been to render the work more efficient as a teacher of the Art of Beasoning in either the closet, the parlour, or the schoolroom, without making it less interesting to the railway traveller or the general reader.

Let no one commence the perusal of this book under the impression that he is about to engage in an exercise that is dry, toilsome, or difficult. He will not find it so. Here are no intricate theories in which the reader may become bewildered — no knotty questions by which he may be embarrassed — and no hard word) which he cannot

PREFACE. IX

understand. These belong to metaphysical and to scholastic logic. The system which this work professes to teach is the logic of common sense. That this system is adapted to the spirit of the age, and that the mode of illustration I have adopted is not unsuitable to the subject, seems abundantly shown by the rapid sale of the first edition, and the strong commendations of many of our organs of criticism. It is very gratifying to observe that the first attempt to place before the -million in a simple form the principles of an art hitherto confined to the educated classes should at once have received the approbation of the public, and of so large a number of literary men.

The Author.

London, Oct. 1, 1851.

The first and second editions of this work were published—" by a Fellow of the Royal Society." The Author has now prefixed his name.

J. W. G.

London, May 1," 1852.

This Edition differs from the last only in having an Appendix on the Philosophy of Language.

J. W. G.

London, Jan. 1, 1854.

No alteration has been made in this Edition, and it is not the Author's intention to make any in the future Editions.

J. W. G.

London, July 1, 1857.

PART I. The Introduction to Reasoning

;ect. page

I. — The name and nature of the Art of Eeasoning 2

II. — The subjects of the Art of Reasoning . 5

III — The utility of the Art of Reasoning .... 10

IV. — The dispositions necessary to the Art of Reasoning , . 17

V. — The knowledge necessary to the Art of Reasoning . . 24

PART II. The Principles of Reasoning

I. — The relation of a Subject and its Attributes . . II. — The relation of a Whole and its Parts ....

III. — The relation of Genus and Species

IY. — The relation of Cause and Effect — Physical Causes Y. — The relation of Cause and Effect— Moral Causes . VI. — The relation of Cause and Effect — Conditional Causes VII. — The relation of Cause and Effect— Final Causes . .

45 53

PART III. The Principles op Reasoning— (continued.)

I. — Reasoning from Examples 127

tl. — Reasoning from Analogy, Comparison, and Contrast . 143

Xll CONTENTS.

III. — Seasoning from Parables, Fables, and Proverbs . . . 166

IV. — Seasoning from Written Documents 184

V. — Errors in Seasoning 201

PAET IY.

The Forms of Seasoning.

I. — Descriptive Seasoning 224

II. — Interrogative Seasoning 237

III. — Conversational Seasoning . . . » 249

IV. — Seasoning by Single Syllogism 261

V. — Seasoning by Compound Syllogism 275

VI. — Series of Seasonings 288

PART V. The Applications op Seasoning

I. — The application of the Art of Seasoning to the ordinary

affairs of life 303

II. — The application of the Art of Seasoning to History . . 313

III. — The application of the Art of Seasoning to Political

Economy 325

IV. — The application of the Art of Seasoning to Statistics . 334 V. — The application of the Art of Seasoning to Moral

Philosophy 349

VI. — The application of the Art of Seasoning to the formation of habits of reasoning 357

Index 881

List op Works.

LOGIC FOB THE MILLION.

You are informed, gentle Reader, that this book is written upon the Art of Reasoning, and is divided into Five Parts. The First Part treats of the Introduction to Reasoning ; the Second and Third Parts treat of the Principles of Reasoning; the Fourth Part treats of the Forms of Reasoning ; and the Fifth Part treats of the Applications of Reasoning.

Part I. The Introduction To Reasoning

It seems proper that before we attempt to reason, we should understand something of the Name and Nature of the Art of Reasoning — of the Subjects on which we Reason — of the Utility of Reasoning — of the Disposition of Mind we should possess while engaged in Reasoning — and of the Information that we should previously acquire. These several topics will therefore form the subjects of the five following Sections, which, taken together, are called "An Introduction to the Art of Reasoning."

B

Section I. The Name And Nature Of The Art Of Reasoning

The art of reasoning is called Logic. But you know Shakspeare has said —

"What we call a Rose, By any other name would smell as sweet."

In the present case we have no occasion for any name. We might simply say the " Art of Reasoning." In the same way we say the art of nursing, the art of teaching, the art of dancing, or the art of fencing. Had either of these arts a Greek name, a writer would begin his treatise with stating the meaning of this name ; and probably learned men would differ as to the propriety and extent of its application.

There is, however, a convenience in giving distinct names to distinct branches of knowledge. But have a care of supposing that because an art or a science has got a hard name, there must be something very difficult in the art or science itself. Many of our arts and sciences were taught by the Greeks, and when our learned men first wrote upon them in English, they very naturally called them by their Greek names. Thus, the word logic is derived from a Greek word (logos) that signifies discourse. But these words have no natural connexion with the arts and sciences to which they are applied. You will have made no unimportant step in a knowledge of the art of reasoning, when you at all times recollect that the names of things are quite distinct from the things themselves. All the processes of reasoning can be as clearly described in " Household Words " as in those Greek words in which they are usually expounded. To reason clearly and forcibly, it is not necessary that you should understand any other language than your own.

" Argumentation or reasoning," says Dr. Watts, " is that operation of the mind, whereby we infer one thing, that is,

WHAT IS LOGIC 1 3

one proposition, from two or more propositions premised* Or it is the drawing a conclusion, which before was either unknown, or dark, or doubtful, from some propositions which are more known and evident. So when we have judged that matter cannot think, and that the mind of man doth think, we then infer and conclude, that therefore the mind of man is not matter.

" So we judge that a just governor will make a difference between the evil and the good ; we judge also that God is a just governor ; and from thence we conclude, that God will make a difference between the evil and the good.

" This argumentation may be carried on further, thus : God will one time or another make a difference between the good and the evil ; but there is little or no difference made in this world ; therefore there must be another world wherein this difference shall be made.

" These inferences or conclusions are the effects of reasoning, and the three propositions taken all together are called a syllogism or argument."

" Archbishop Whately," observes Mr. Mill, " has denned logic to be the science as well as the art of reasoning, meaning by the former term the analysis of the mental process which takes place whenever we reason ; and by the latter the rules grounded upon that analysis for conducting the process correctly.

" Logic then comprises the science of reasoning, as well as an art founded on that science. But the word reasoning, like most other scientific terms in popular use, abounds in ambiguities. In one of its acceptations it means syllogising; in another of its senses, to reason is simply to infer any assertion from assertions already admitted. The latter and more extensive signification is that in which I mean to use it.*

" Our object will be to attempt a correct analysis of the intellectual process called reasoning or inference, and of such other mental operations as are intended to facilitate this, as well as on the foundation of this analysis, and pari passu with it, to bring together or frame a set of

* " I am myself disposed to think that any fact which can he shown to he implied or contained in another fact may conveniently and properly he said to be inferred from it, and that the process may be with equal convenience and propriety termed reasoning." — Bailey's Theory of Reasoning, p. 41.

b2 rules or canons for testing the sufficiency of any giver* evidence to prove any given proposition."

The reader will perceive that Mr. Mill's book is written on the science of reasoning. Our book is written on the art of reasoning. We use the word reasoning in the wider sense used by Mr. Mill, and as including what is denoted by arguing, proving, inferring, confirming, refuting, and all similar words, in the sense in which they are popularly understood. A knowledge of the art of reasoning is essential to the study of the science ; but an acquaintance with the science is not necessary to the practice of the art. Indeed it is only by the use of the art that the science can be studied. We meddle not with the science. We profess not to analyse any of the powers of the mind, nor to lay down any new rules for conducting the process of reasoning. We shall attempt only to describe those rules that are already known, and to apply them correctly. And we shall consider their application chiefly with reference to those things with which people are most familiar.

If a man who understands grammar hear a person say. " I speaks," he will know, from general practice, that the language is improper ; but he will, moreover, quote the rule, that " a verb should agree with its nominative case in number and person." Now, a collection of such rules form grammar, or the art of speaking correctly. So, if a man hear a person say — " All men are liars, for a party has just told me a lie," he will know from his own common sense that this is not sound reasoning ; but if he has studied logic, he will also cite the rule, " Universals cannot be inferred from particulars." Now, a collection- of all these rules form logic, or the art of reasoning correctly ; and the man who has a knowledge of these rules, and is correct and ready in applying them in practice, is called a logician. A man may reason accurately without rules. But if he can give the rules, he will have more confidence in the truth of his reasonings. He will also be better able to perceive the incorrect reasonings of others, and to show the soundness or unsoundness of any opinions propounded for his consideration.

These practical rules of reasoning collected together form the art of reasoning, in the same way as a collection

SUBJECTS OF REASONING. 5

of rules for speaking and writing with propriety form the art of speaking and writing with propriety. The one art is called logic — the other art is called grammar. These two arts are useful to each other. Thoughts are expressed in words. If we think clearly we shall speak clearly, and when we are learning to arrange our words with accuracy and order, we are learning to think with accuracy and order.

A person who has acquired a knowledge of grammar will afterwards speak and write grammatically, without ever thinking of the rules of grammar. So a person who has acquired a knowledge of logic, will afterwards reason logically, without ever thinking of the rules of logic. The rules will have become so deeply fixed in his mind that he will habitually reason accurately ; and by practice he will come to reason promptly and forcibly. It is the chief business both of grammar and logic to teach us how to avoid errors. Grammar teaches us how to avoid the use of words and sentences that are contrary to its rules. But a beautiful or powerful style of writing must arise from the constitution of our own minds, or the peculiar direction of our studies, and is not to be acquired merely by an observance of grammatical construction. So logic teaches how to know and to discard bad arguments. To be able to reason promptly and forcibly, depends upon our attainments in knowledge — the constitution of our mental powers — the extent of our practice — and the degree with which we are familiar with the writings of those learned men who are celebrated as the masters of the art of reasoning. Dr. Campbell, in his Philosophy of Rhetoric, compares logic to the soul, and grammar to the body ; the union of both being essential to an excellent discourse.

Section II. The Subjects Op The Art Of Reasoning

The human mind can think, can reason, can remember. How it performs these operations we do not know. It does perform them, that 's certain. 'Tis equally certain that these operations are distinct from each other. The

LOGIC FOE THE MILLION.

mind may think of things without reasoning about them ; and it may remember things without reasoning about them. We shall in this section take a view of those truths with which we become acquainted by other means than reasoning. They may be classed into truths of the senses — truths of consciousness — truths of the intellect — and truths of testimony. On these topics we shall quote Dr. Watts.

1. Truths of the senses : —

" The evidence of sense is, when we frame a proposition according to the dictates of any of our senses ; so we judge that grass is green ; that a trumpet gives a pleasant sound ; that fire burns wood ; water is soft ; and iron is hard ; for we have seen, heard, or felt all these. It is upon this evidence of sense that we know and believe the daily occurrences in human life ; and almost all the histories of mankind, that are written by eye or ear-witnesses, are built upon this principle.

"Under the evidence of sense we do not only include that knowledge which is derived to us by our outward senses of hearing, seeing, feeling, tasting, and smelling ; but that also which is derived from the inward sensations and appetites of hunger, thirst, ease, pleasure, pain, -weariness, rest, &c.,and all those things which belong to the body ; as, ' hunger is a painful appetite ; light is pleasant ; rest is sweet to the weary limbs. 5 "

2. Truths of consciousness : —

" As we learn what belongs to the body by the evidence of sense, so we learn what belongs to the soul by an inward consciousness, which may be called a sort of internal feeling, or spiritual sensation of what passes in the mind; as, 'I think before I speak ; I desire large knowledge ; I suspect my own practice ; I studied hard to-day ; my conscience bears witness of my sincerity ; my soul hates vain thoughts ; fear is an uneasy passion ; long meditation on one thing is tiresome. 5

" Thus it appears that we obtain the knowledge of a multitude of propositions, as well as of single ideas, by those two principles which Mr. Locke calls sensation and reflection ; *one of them is a sort of consciousness of what affects the body, and the other is a consciousness of what passes in the mind."

3. Truths of the intellect : —

" Intellect relates chiefly to those abstracted propositions which carry their own evidence with them, and admit no doubt about them. Our perception of this self -evidence in any proposition is called intelligence. It is our knowledge of those first principles

SUBJECTS OF REASONING. 7

of truth which are, as it were, wrought into the very nature and make of our minds : they are so evident in themselves to every man who attends to them, that they need no proof. It is the prerogative and peculiar excellence of these propositions, that they can scarce ever be proved or denied : they cannot easily be proved, because there is nothing supposed to be more clear or certain, from which an argument may be drawn to prove them. They cannot well be denied, because their own evidence is so bright and convincing, that, as soon as the terms are understood, the mind necessarily assents ; such are these, — ' whatsoever acted hath a being ; nothing has no properties ; a part is less than the whole ; nothing can be the cause of itself. 5

" These propositions are called axioms or maxims, or first principles ; these are the very foundations of all improved knowledge and reasonings, and on that account these have been thought to be innate propositions, or truths born with us."

4. Truths of testimony : —

" When we derive the evidence of any proposition from the testimony of others, it is called the evidence of faith; and this is a large part of our knowledge. Ten thousand things there are which we believe merely upon the authority or credit of those who have spoken or written of them. It is by this evidence that we know there is such a country as China, and there was such a man as Cicero, who dwelt in Rome. It is by this that most of the transactions in human life are managed : we know our parents and our kindred by this means, we know the persons and laws of our present governors, as well as things that are at a vast distance from us in foreign nations, or in ancient ages.

'•According as the persons that inform ns of anything are many or few, or more or less wise, and faithful, and credible, so our faith is more or less firm or wavering, and the proposition believed is either certain or doubtful ; but in matters of faith, an exceeding great probability is called a moral certainty" *

The truths of reasoning are distinct from all these. They are derived from these truths, or such as these, by natural and just methods of argumentation.

As logic is the art of reasoning it has nothing to do with those truths that are self-evident, or which are known to be true without reasoning. The positive testimony of the

* Mr. Bailey observes (p. 29), " In philosophical strictness, we can he said to know only those things which we perceive, or have perceived, through our organs of sense, and those states of mind or mental events of which we are or have been conscious. Other things we believe on evidence more or less cogent ; that is to say, they are matters of inference." If so, the " truths of testimony" -will have to be classed under "truths of inference." But the word know is often used in a more extended sense.

senses supersedes the necessity for reasoning. If you have the tooth-ache or the gout, you want no logic to prove to you that you suffer pain. And as we know what passes without us, by the organs of hearing and seeing — and what passes in our bodies, by means of our sensations — so we know what passes in our minds, by means of consciousness. We know that we think — that we judge — that we remember. We know that we hope and we fear — we love and we hate. All these, and a variety of other operations and feelings, pass within our minds ; and we want no logic to convince us of their existence. There are also many other truths that are self-evident. We know that two and two make four — that a part of anything is less than the whole — that a cause must precede the effect — and that a proposition cannot be both true and not true at the same time, and in the same respect. These are called first truths, or truths of intuition. They are wrought into our very nature, and we cannot disbelieve them, if we would. If we meet a man who denies them, we do not reason with him. We conclude either that he does not understand the meaning of the words, or that he has lost his reasoning faculties. — Here logic has nothing to do.

As logic is merely the art of reasoning, it follows that logic has nothing to do with those mental operations in which we do not reason. The mere giving or receiving of information is not reasoning. If you say to a friend, " It is a cold day," there is no logic in that. But if you say, " I think we shall have rain in the course of the day," that is a logical conclusion ; and if asked to do so, you should be prepared to give reasons for your opinion. So the acquisition of knowledge by reading or hearing is not reasoning. You may possibly read history or biography, learn several languages, and become acquainted with botany, natural history, and several sciences, without reasoning. All this requires nothing more than a good memory. And hence it is possible to become a very learned man and yet not be a logician. But if you begin to reason about anything you learn, you immediately become a logician. Take, for illustration, a case in history. You have read the life of Napoleon Bonaparte, and you remember all the events recorded, and also the opinions of the historian. You are no logician

SUBJECTS OF REASONING. 9

here'. But if you stop to ask if any particular event be true — if you inquire whether in certain actions he evinced sagacity or courage — and consider what were the effects of his course on the state of Europe — as soon as you commence to discuss these or any similar questions, you become a logician.

As logic has nothing to do with receiving or retaining information, so also it has nothing to do with imparting information, or with the giving of advice or commands. There is no logical process in the following words — " Be not wise in your own conceit — Recompense to no man evil for evil — Provide things honest in the sight of all men — ■ If it be possible, as much as in you lieth, live peaceably with all men — Be not overcome of evil, but overcome evil with good." — But sometimes the terms, though simply the language of advice or command, will imply a logical process: thus — "Go to the ant, thou sluggard; consider her ways and be wise," w T hich implies that there is some connexion between going to the ant and becoming wise ; and thus it denotes a logical process in the mind of the speaker. So also, if a motive is added, this brings the command or advice within the province of logic : thus — " Honour thy father and thy mother, that thy days may be long in the land " — " Honour the Lord with thy substance, and with the first-fruits of all thine increase ; so shall thy barns be filled with plenty, and thy presses shall burst out with new wine."