MASTER N EG AT I VE NO. 92-80715 MICROFILMED 1992 OLUMBIA UNIVERSITY LIBRARIES/NEW YORK as part of the "Foundations of Western Civilization Preservation Project" NATIONAL ENDOWMENT FOR THE HUMANITIES J „ ^o,, nnt h<» made without permission from Reproductions may not "^ ™^"^.;,fV"5" ,i^ Columbia University Libraiy COPYRIGHT STATEML The copyright law of the United btates - i itie i / , uniiea States Code - concerns the making of photocopies or other reproductions of copyrighted material... Columbia University Library reserves the right to refuse to accent a copy order if, in its judgement, fulfillmeni oi the order would involve violation of the copyright law. AUTHOR: CLARKE, RICHARD FREDERICK TITLE: LOGIC PLACE: NEW YORK DATE: 1889 COLUMBIA UNIVERSITY LIBRARIES PRESERVATION DEPARTMENT RTnT.TOCRAPHIC MICROFORM TARGET Master Negative # Original Material as Filmed - Existing Bibliographic Record ■■■■nMwa mm Restrictions on Use: 160 C55 Clarke, Richard Frederick. ###f#-^^:^>^ ... . Logic, by Richard F. Clarke, S. J. No w iin |»F-etTtyie*i. London, New York, [etc.], Longmans, Green, and Co.. ig^-lBSdm xix, 497 p. diagrs. igi**". (,-/f/ I has been hitherto no text-book which could be put into their hands for the purposes of private study. The Latin treatises which form the basis of the lectures attended by the young ecclesiastic are quite unsuited for them, apart from the mere difficulties of the language. Their strange phrase- ology, the technicalities of their style, the cut and dried method they pursue in their advance from principles to conclusions, their complete severance from modern habits of thought and speech, render them unintelligible to ordinary students without an elaborate explanation on the part of the teacher. He has to cover the dry bones with flesh, to enlarge, illustrate, translate, and simplify, and often entirely reconstruct, before he can reach the average intelligence or rouse any interest in his pupils. The English text-books hitherto issued have been little more than a literal translation from the Latin, and though they have done a good work in furnishing students unversed in Latin with text- books in their own language, yet they have not attempted the further task of translating scholastic into nineteenth-century phraseology. It is hoped that the present Manual may put before our Catholic youth this most important branch of study in a more simple and attractive form. The scholastic terms have not been discarded, but they have been carefully explained and rendered into words which will convey to the man of average edu- cation their real meaning. While the scholastic system has been closely adhered to throughout, the dress in which it is clothed is modern, and no previous knowledge is necessary for the young Catholic in whose hands it is placed. There is another class to whom it is hoped that the present text-book may prove useful. Many a Protestant student, perplexed and bewildered by the rival claims of half a dozen different systems, each at variance with the rest, and often also at variance with itself as well, is inclined to give up the search for truth in despair and to fall back on the Hamiltonian doctrine of the Relativity of Knowledge, or in other words, on the non-existence of truth at all. Such a one often craves in his heart after some leader on whom he can rely, some one who represents, not the newly-fangled inven- tions of the individual, but the traditional authority of centuries. He would fain know whether amid Catholic philosophers there is the same discord and the same contradiction as among Protestants, and would eagerly drink in the teaching of one who speaks, not in his own name or that of some modern theorizer, but in the name of the men of XIV PREFACE. PREFACE. XV genius, who gave themselves to the study of Logic from the days of Aristotle till the unhappy period when the old learning was discarded with con- tempt by the ignorance of the Reformers. To any such inquirer this text-book offers the ordinary Catholic teaching grounded on Aristotle and set forth by St. Thomas of Aquin, which flourishes as vigorously as ever in every centre of higher Catholic education. If there is any departure from the doctrines of St. Thomas in these pages, it is there without the knowledge of their writer, whose object it has been to follow throughout in the footsteps of the Angelic Doctor. There is another class to whom such a text-book as this will be a real boon, to whose existence the writer can testify from personal experience. Con- verts to the Catholic Church, trained in the English Colleges and Universities, have unconsciously drunk in a number of principles, some true, some false, from their earliest years, and are often not a little puzzled to discern the true from the false. Perhaps in their early days Hamilton and Jevons, Mansel or Veitch, had represented to them the orthodox school, and Mill and Spencer and Hegel a more consistent and at the same time more sceptical system. On submission to the Church, they would fain know how far these rival claimants possess any fragments, large or small, of solid truth, and where they each and all wander away into error. In the following pages this need has been kept in view, and the Author has sought to write what would have been useful to himself twenty years ago, when he made unsuccessful endeavours to master by private study the principles of Catholic philosophy from inscrutable Latin text-books. Last of all we must remember that in these days the old ideas respecting the limits of feminine education have been not a little modified. This is not the place to discuss the advantages and disadvantages of a more enlarged intellectual train- ing for women. It is enough to say that the change which is being introduced is in many respects only a re-assertion of what was common enough in Catholic times. It is an undoubted gain to the cause of Truth that women of cultivated tastes should be trained to think correctly, and should have such a knowledge of the principles of Logic as may help them thereto. In Convent schools and other Catholic institutions the higher education is steadily making way, especially in the United States, and the study of Logic is an im- portant element in it. The present volume is one which, even if it is not put into the hands of the younger students, is well suited for the I, ^1 dfr ^ -.Tlii^ -^ujuj XVI PREFACE. Teacher's use in the instruction of her Catholic pupils, as well as for those whose general training may give them an interest in the subject and a desire to investigate it for themselves. One word to those who may desire to know the best order in which to study the various parts of CathoHc Philosophy. Ahhough this Text-book of Logic has not been the first to appear in order of time, it is the one which naturally comes first in order of thought, and the Student is recommended to pass from it to the Text-book of First Principles, and so on to Ethics, Natural Theology, Psychology, and the difficult though important subject of General Metaphysics. CONTENTS. INTRODUCTION. Chapter I.— The Province of Logic II. The Definition of Logic III. — The Foundations of Logic . I. The Principle of Contradiction II. The Principle of Identity IV.— The Foundations of Logic (continued) v.— The Foundations of Logic {continued) III. The Principle of Causation . IV. The Principle of Excluded Middle . VI.— The Three Operations of Thought PAGE I 15 29 33 42 50 71 72 79 92 PART I.-OF SIMPLE APPREHENSION OR CONCEPTION. Simple Apprehension . VII. Simple Apprehension {continued). Errors respecting it VIII.— The Doctrine of Universals IX.— The Heads of Predicables . X.— Definition XI. — Division . • • • Modern 97 121 140 163 193 225 CONTENTS. PART II.— OF JUDGMENT OR ASSENT. PAGE Chapter I. — ^Judgment. ..... 245 Divisions of Judgment . . . .250 II —Propositions, their Nature and Divisions 261 Divisions of Propositions . . . 266 •I in. — Import of Propositions. Various kinds of Propositions ..... 280 »i IV. — The Opposition and Conversion of Pro- positions . . . . .293 PART III.— OF REASONING OR ARGUMENT. Chapter I. II. -Reasoning -The Syllogism and its Laws Canons of the Syllogism . Dictum de omni et nullo General Rules of the Syllogism . III—The Figures of the Syllogism Rules of the First Figure Rules of the Second Figure Rules of the Third Figure Rules of the Fourth Figure Reduction IV.— Various kinds of Syllogisms Other Variations of the Syllogism v.— Formal Induction VI.— Material Induction . , Method of Agreement . , Method of Difference Method of Concomitant Variations Method of Residues Reduction 305 313 315 316 316 324 332 333 334 335 339 348 356 364 376 389 390 393 395 i VyV/l' •» x-x^ A w. page Chaptei ^ VII.— Example and Analogy . 402 Example . . • • • Analogy . . . . ■ . 402 . 407 II VIII The Matter of the Syllogism . . 412 I. Demonstrative Syllogisms II. Probable Syllogisms . . 419 . 424 II IX. — Fallacies . 432 I. Fallacies of Language II. Fallacies outside Language . . 434 . 445 II X.— Method and its Laws APPENDIX. . 461 The Scholastic Method 475 LOGIC. Part I. CHAPTER I. THE PROVINCE OF LOGIC. Importance of Logic— Aim of Logic— Meaning of the word— Logic and Grammar— Logic in its relation to Thought— Different meanings of Thought— Logic and Psychology— Logic and Meta- physics—Formal and Material Logic, and their respective provinces— Formal Logic necessary to Material— Meaning of Formal Logic— The Laws of Thought— Logic in its relation to the Laws of Thought. The importance of the study of Logic is derived from its undeniable claim to an universal dominion over the minds of men. No one can ever think correctly unless he thinks logically. No one can judge aright unless his judgment is one which Logic can approve. No one can arrive at well-grounded conclusions unless he argues in conformity with the laws of Logic. He who professes a system of Philosophy, or Theology, or Science which is in any respect opposed to logical principles, thereby declares his system to be false and irrational, and himself an intellectual impostor. Logic must of necessity control with its unerring laws every pro- cess of thought, every act of judgment, every chain B H THE PROVINCE OF LOGIC. MEANING OF THE WORD. of argument ; else the process of thought is faulty, the act of judgment unwarrantable, the chain of argument incorrect. The ultimate end aimed at in the study of Logic is to train the human mind to exactness of thought. It is not to make a man ready in argument, nor to add to the stock of human knowledge, but to teach us to think correctly. As in a liberal education the end aimed at is not to impart to the student a vast number of accumulated facts, but to stimulate the desire for acquiring information for himself, to furnish him with the means of doing so, and to enable him to make a good use of the information when acquired, so the ultimate object of the study of Logic is not so much to supply us with a detailed analysis of our processes of thought, as to ensure their correct performance. This is the end it has in view in laying down the Laws of Thought which are its foundation, and in analyzing the various operations which fall within its province. This it aims at still more directly in pointing out the mani- fold dangers to which thinking is exposed, and the fallacies by which the thinker is most liable to be deceived. It seeks to arm the logical student cap-a-pie, so that he may be able to detect at a glance the incorrect judgment or unwarranted assumption. It gives him the clue to the carefully concealed fallacy, and enables him to expose its weakness, to show where the inference is faulty, or where the terms are used in an ambiguous sense, or where statements are put forward as identical when they are really different from each other. But what is Logic ? Before we consider this question, we will look at the origin of the word, as an useful guide to its true meaning. Logic is derived from the Greek Logos, which has the double meaning of word and thought. It is used in classic authors indiscriminately for the internal word present in the mind, and the external word uttered by the lips. It has, therefore, no exact equivalent in English, although in theological lan- guage word is sometimes used for that which is hidden in the intellect without finding externa.1 •expression. I But such usage is exceptional, and in ordinary English word implies some form of spoken language. The double use of the Greek word Logos corre- sponds to the double nature of the subject-matter of Logic. As Logos is primarily the internal thought, and secondarily the external expression of the thought, so Logic is primarily concerned with thought, secondarily with language, as expressing thought. The connection between correct thought and correct language is so intimate, that any branch of knowledge which treats of the one must to some extent include the other. Logic, therefore, as being concerned wdth thought, is necessarily concerned also with language. Here we see its relation to Grammar. Both Logic and Grammar have to do ^ Thus The Word is used to express the Second Person of the Blessed Trinity, the Eternal Wisdom of God, hidden in the Intellect of the Eternal Father before all ages ("The Word was made Flesh "), and also the interior voice speaking with Divine authority to the mind of the prophets ("The word of the Lord came to Jonas," &c.). THE PROVINCE OF LOGIC. with thought and language, but Logic has to do with thought primarily and essentially, and with language secondarily, and only so far as it affects thought, whereas Grammar, on the other hand, treats of language primarily and essentially, and of thought only secondarily, and so far as is necessary for the due treatment of language. Logic then is a branch of knowledge concerned with Thought. But this is not sufficient for our Definition. What do we mean by Thought ? Has Logic to do with all our thoughts ? Does it include an investigation into the origin of Thought, the subject-matter of Thought, the various mental pro- cesses which are connected with Thought ? Does it treat of Thought in general, or is it limited to some special province or department of Thought ? In order to have an accurate knowledge of the province of Logic, we must first of all have an accurate knowledge of Thought. Thought is used in two different senses. I. It is sometimes used to include every mental process, every activity of those faculties which belong to the sphere of intelligent (as distinguished from intellectual) life. Thus I say that my friend in Australia is in my thoughts, and by this I mean that he is present in my memory, and his image dwells in my imaginative faculty. A child is said to be thinking of its dinner, when we see it restless and fidgetty in the school-room as the time of its mid- day meal approaches, and we mean thereby that a vague, half-conscious recollection of the expected food, and a desire to partake of it, is present to its LOGIC IN ITS RELATION TO THOUGHT. mind. In this sense animals may be said to think. The dog thinks of the rat when his master makes a scratching noise in the corner of the room ; he thinks of the pain of some recent castigation when he sees the whip. Thinking, in this meaning of the word, belongs to the material faculties of memory and imagination, as well as to the immaterial faculty of intellect.' 2. Thought is also used in the narrower and stricter sense of the exercise of our intellectual faculties properly so called, of that immaterial faculty which brings within the range of our know- ledge things above and beyond sense, which recog- nizes in things sensible that which is suprasensible, and contemplates under the external appearance the underlying nature. It is the recognition m things around of that which makes them to be what they are, of the inner reality hidden under the shell of the external and material object of sense, of that which in scholastic language is termed the essence, or quiddity, because it answers the question,^ What is this ? Quid est hoc ? Thought is the grasping of that common nature which is the foundation of all classification, and binds together existing things I When thought is used in this sense, it is true that in the case of rational beings there is a real intellectual apprehension, since this necessarily accompanies every act of their imagination. But it is the sensitive act of which we are speaking when we use in reference to such acts the word think, since we employ it in the same sense of the acts of men and of the lower animals. ^ Quidditas is the somewhat barbarous, but very expressive equivalent of the Aristotelian phrase. t6 rl fiv fivai. The essence or quiddity of a thing consists in its corresponding to the pattern THE PROVINCE OF LOGIC. into what we call classes, or kinds, or species. It is the apprehension of things immaterial and spiritual, and of things material only after its own immaterial fashion. But it is more than this. It also includes those processes by which the intellect compares together the ideas which it has framed for itself from objects about and around us, pronounces on their agreement or disagreement, declares them to be compatible or incompatible, identical or different from each other. The decisions thus arrived at it places side by side, and from them passes to further propositions deducible from them, comparing these together in their turn, and thus constructing arguments and chains of argument with an activity of which the only limit is the finite character of Thought. In other words. Thought apprehends, judges, reasons, not about individual objects, apprehended directly and immediately as individuals, not about sensible things in their capacity of objects of sense, but about the inner nature which underlies all things, whether sensible or suprasensible, material or spiritual, and which intellect alone can grasp and make its own. Animals therefore are incapable of Thought in this higher sense. Their knowledge is limited to things sensible and material, and that which is essentially dependent on sense and matter. They have no capacity for apprehending the inner nature after which it was fashioned. Hence ri ^»'=what is its nature? what was it intended to be by its Creator ? And therefore rh ri ^v thai = the being what it was intended to be by its Creator. DIFFERENT MEANINGS OF THOUGHT. of things. Animals can form a sort of judgment, it is true, about things of sense, and act in consequence of sensible impressions, as if they drew a conclusion from such judgments, in a way that often strangely counterfeits intellectual activity, but they never get beyond the region of sense, and exercise their facul- ties on objects which admit of being painted on the Imagination, not on those which belong to the special province of Intellect. But is Logic concerned with all that concerns Thought ? with the processes, for instance, by which materials are supplied to the intellect for it to think about ? or with the various phenomena of Thought that observation and experience reveal to us ? Is it concerned with the reliance to be placed on our thoughts, and their correspondence with the things about which we think ? Does an investigation into the various faculties of the mind that think, and of their mutual relation to each other, lie within the scope of Logic? While we contend for all reasonable liberty in defining the domain of Logic, we must be careful not to encroach on kindred sciences. Logic is not concerned with an analysis of our thinking faculties. This belongs to Psychology, or the science of life, of intellectual life, as well as of its lower manifestations. To Psychology, moreover, belongs the study of the various phenomena of thought, of the facts of intellect that we gain by observation. To Psychology belongs the analysis of the processes previous to Thought, by which materials are furnished to the Intellect. To Psy- 8 THE PROVINCE OF LOGIC. chology belongs the determination of the exact distinction between the sensitive and the non-sensi- tive faculties of the mind, and of their mutual dependence on each other, and though the two sciences have a certain amount of common ground, yet we may say in general that Psychology is con- cerned with all the operations of mind in its widest sense, while Logic is concerned only with those which contribute to correct thinking. Nor is Logic concerned with the objects about which we think, except in so far as they are repre- sented in the thinking mind. Regarded in them- selves they fall under the domain of Metaphysics, which investigates the inner nature of things, and regards them as in themselves they are. The science of Metaphysics determines the nature of various forms of beings of essence and substance, of cause and effect, of goodness, unity, and truth. It treats of that which lies outside the mind, and contemplates it in its objective reality. Logic, on the other hand, treats of that which is within the mind only, and contemplates it in so far as it is a part of the intellectual furniture. But is it within the province of Logic to decide on the reliance to be placed on our thoughts, or their trustworthiness as representations of the internal objects about which we think ? Here we come on an important distinction between the two parts of Logic. I. Formal Logic has a limited, though a most important province. Its jurisdiction- is confined to those thoughts which already exist within the mind FORMAL AND MATERIAL LOGIC. and have passed the barrier between intellect and sense. It has to take for granted that the processes by which they have been received were correctly performed. It accepts such thoughts as the materials it has to employ, it pronounces on their character as thus received, on their various rela- tions to each other, whether of inclusion or exclu- sion, compatibility or incompatibility, and from the decisions passed it passes on to other decisions, compares one with another and pronounces some fresh decision as the result of the comparison. It discusses the ideas which are the objects of thought, and the judgments which express their mutual relation, and the arguments which result from com- bined judgments. Furthermore, as ideas ^ judgments, arguments, must all be expressed in words, it treats of terms as expressing ideas, propositions as expres- sing jW^wj^w^s, syllogisms as expressing arguments, 2. Material or Applied Logic includes a much wider province. It is not satisfied with taking its materials for granted, but examines into the processes by which those materials are brought into the mind, so far as is necessary to their being correctly performed. It includes the consideration of the correspondence of the object of thought as it exists in itself and as it exists in the thinking mind. It pronounces on the nature of evidence, on the various degrees of certitude from absolute ignorance to the highest possible assurance of truth : on the various grounds of certitude : on the distinctions of doubt, opinion, knowledge, faith, on the necessity of some kind of certitude if we are to think at all, and 10 THE PROVINCE OF LOGIC. of the consequent folly of universal scepticism. It acts the part of critic and investigator of truth, and its investigations carry it outside the limits of the thinking process properly so called, in order that it may defend this process against the dangers to which it is exposed from without. In the present volume we shall confine ourselves, though not with the rigour of too close an exactitude, to Formal Logic. Material Logic is rather a part of Fundamental Philosophy, and would lead us too far afield. Yet we shall find it necessary to speak of certain processes which strictly speaking lie outside Formal Logic on account of the confusion that has been introduced by the speculations of various modern authors, who make it necessary for us from time to time to make excursions outside our own proper province in order to keep its limits intact, and beat our opponents back when they seek to bring confusion into the realm of Logic Pure. Formal Logic is moreover the ally and the most useful ally of Material Logic. Although it takes its materials for granted, yet indirectly it detects error admitted from without. For as we derive our thoughts and our judgments from countless different sources, any error existing in the mind is sure to find itself sooner or later at variance with some truth which is already settled there. Formal Logic detects the inconsistency and declares that the intruder must be driven forth. There cannot be harmony in the soul as long as error remains there ; and Formal Logic detects the jarring note. It leaves indeed to Applied Logic the task of watching MEANING OF FORMAL LOGIC. II at the gate and demanding the passport of propo- sitions which demand admission into the mind, but it exercises a vigilant surveillance over those already within. Besides this, it has at its service a body of efficient auxiliaries in the shape of necessary truths which do not come from without at all (except so far as external things are the occasion of their birth), but are the citizens who are born within the thinking mind. They are the ready instruments of Formal Logic, and as they can never be driven out unless absolute anarchy prevails, they are most useful in ' thrusting forth the stranger who is not furnished with a passport, however plausible and fairspoken he may be. There are, in truth, very few errors (and those are errors of fact and not of principle) which Formal Logic does not supply the means of detec- ting and expelling from the mind. But what is the meaning of Formal Logic " It is that part of Logic which deals with the forms according to which all correct thought proceeds with the laws which regulate thought, the universal and irrefragable rules which must govern every act of thinking, if it is to be correct. Formal Logic supposes its materials already received and trans- formed into the intellectual pabulum suitable for its own use. In using these materials the intellect, from the necessity of its rational nature, has certain fixed and unchangeable conditions under which it thinks. It is from an analysis of these conditions, from an investigation of its normal method of procedure that the laws which govern the intellect are ascertained, and it is the business of 12 THE PROVINCE OF LOGIC. Formal Logic to enunciate these laws, to enforce their observance on every thinker and to allow no sort of deviaticn, even by a single hair's-breadth from their enactments. It has to proclaim these laws eternal and immutable as God Himself, and to pronounce its anathema on all who declare that they admit of any exception under any circumstances whatever. From the beginning to the end of time, nay before Time was and after Time shall be no more, in any conceivable world which God has created or could create, these laws are unchangeable and inviolable, and God Himself cannot interfere with them in their very smallest detail. For they are the foundation of all Truth and are themselves founded upon the nature of the God of Truth. God could not violate them without ceasing to be God, and man cannot violate them without violating that rational nature which he possesses in virtue of his creation in the Hkeness of God. Logic, therefore, in the sense in which we are using it, is concerned with the Laws of Thought. But not with all the laws which may be termed laws of thought. For the expression admits of two different meanings. A Law of Thought may be a law which regulates the relation of thought to the out- side world, and ensures the correspondence of the thought to the objects thought of. Such a law would be a material Law of Thought. For instance, after a certain amount of careful observation and research, I feel myself justified in laying down the proposition ; A II tortoises are slow in their movements, and I apply to the logician to know whether I am THE LAWS OF THOUGHT. 13 conforming to the laws of correct thinking in the process which has led me to this conclusion. The law about which I ask is a law which has to decide the amount and the nature of the internal investiga- tion which justifies me in uniting together in one judgment the idea of tortoise and the idea of slow- ness of movement. It is a law regulating the accep- tance of the materials of thought. It involves external research, and cannot be arrived at by a mere comparison of the two ideas. It is therefore a material law, and Formal Logic cannot pronounce upon it. It is not a law of Thought itself as Thought. It is not a law which may be known independently of any reference to things outside. It belongs to Material Logic to pronounce whether I have fulfilled the conditions requisite to ensure certitude in the assertion of the proposition in question. But if I submit to the logician the proposi- tion, ^// spirits are immaterial beings, and ask him whether I am safe in asserting it, he as a formal logician can answer me at once. The process by which that proposition is arrived at needs no outside investigation. It involves nothing more than a comparison of the thought or idea of spirit and the thought or idea of immaterial being. Spirit implies immaterial, and the process of com- parison which leads me to combine the two in my judgment is a process of Formal Logic strictly so called. The law which regulates the process is a formal, not a material law, a law which is entirely independent of external observation and research, a law which follows from the nature of Thought as Thought. THE PROVINCE OF LOGIC. Hence Logic is concerned with the Formal Laws of Thought, with the Laws of Thought as Thought, with the laws which concern Thought alone, in and by itself. Even when thus restricted the field of Logic is sufficiently wide. Its sway extends over all our thoughts. It has a word to say to us whenever we think. It sits on its tribunal on every occasion on which our intellect performs any intellectual operation whatever. Even though Formal Logic disclaim any interference with the introduction of materials from outside into the thinking mind, or with the faculties which supply those materials, or with the nature of the mind itself which thinks, still it is true to say that we cannot think a thought without Logic having a control over it. This is why we begin the study of Philosophy with Formal Logic, for unless it stamp its approval on our mind's work, that work all counts for nothing. If Logic can show a flaw in our thinking process, if it can point out a single idea inconsistent with itself, or a judgment in which subject and predicate are incompatible, or a conclusion at variance with the premisses or which does not follow from them, the whole argument has tn be put aside as valueless, until it has conformed to the ruthless and inflexible laws of Formal Logic. CHAPTER 11. THE DEFINITION OF LOGIC. Summary of preceding Chapter— Is Logic an Art or Science? —Distinction of Art and Science— Science learned by Study, Art by practice— The Laws of Science immutable— Art mutable— Science concerned with what already exists, Art with production— Application of this to Logic— Logic primarily a Science, secondarily an Art— Is the Science of Logic specula- tive or practical ? — Distinctions between them — Logic both speculative and practical — Various Definitions of Logic, (i) Archbishop Whately, (2) Arnauld, (3) Port Royal, (4) J. S. Mill, (5) Arabian Logicians— History of the Name of Logic. Before we proceed with our Definition of Logic, we must sum up the work done hitherto. The all- important end at which Logic aims is exactness of Thought. Logic is concerned with Thought, by which we mean not every mental process, but the operations of intellect and none other. These operations fall under three heads, the consideration of which furnishes the three divisions of a text- book on Logic. Logic, however, is not concerned with an analysis of our thinking faculties, or with the mental processes which necessarily accompany Thought, nor with the external objects about which we think, but only with that which is immediately x6 THE DEFINITION OF LOGIC. IS LOGIC AN ART OR SCIENCE? X7 necessary to correct thinking. It therefore has to deal, (i) with those operations of the Human Intel- lect which take for granted the correctness of the materials supplied from without, and regulate the disposal and development of those materials {Formal Logic) ; (2) with those operations by which is en- sured the correctness of the materials supplied, and their correspondence with the external realities which they represent (Material Logic). We are going to occupy ourselves with Formal Logic, which is so called because it defines the necessary /orms or laws to which all correct Thought as such con- forms itself, not with the laws regulating Thought in its relation to things outside, but with those only which regulate its internal operations in them- selves. The scope of Logic, even under these restric- tions, extends over the w^hole province of Human Thought. We have now arrived at the Definition of Logic so far as this, that it is a branch of knowledge which deals with the Formal Laws of Thought. We have seen, moreover, that it has a practical end at which it aims, that is, has fixed and immutable laws to which all thinking must conform, that it is learned by a careful study of our processes of thought. We are now in a position to discuss the much disputed question whether Logic is an Art or a Science^ or both an Art and a Science ? In order to answer this question satisfac- torily, we must consider a few of the distinctions generally regarded as separating the arts from the sciences. 1. An art is learned chiefly by practice,^ a science by study. Thus painting is an art, embroidery is an art, rhetoric is an art. Each of these indeed, like every art, has a scientific element in it, but its artistic side is in the foreground, and the scientific element is out of sight. None of these arts could be acquired by years of patient study. It is by the labour of continual practice that skill is attained in them, and innate abihty rendered perfect. On the other hand, geometry is a science, political economy is a science, harmony is a science. Even where a certain amount of experience is required, as in medicine , to complete the results of the study and apply its principles, yet this is quite a subordinate element. A man may sit in his study with his books all his life long and be learned in geometry, political economy, and in harmony, and even in medicine, without any practice whatever. 2. A science, again, is based on fixed and im- mutable laws on which it depends for its very existence, whereas an art is always ready to change its method of procedure and to forsake the old paths. Every true art must indeed have an intel- lectual basis, and therefore certain underlying principles that govern it, but in all matters which are not of its essence as an art, it can adopt new methods and new laws, often the very opposite of those to which it has clung hitherto. It is far more pliable than science, and varies almost indefinitely with varying time and place. The laws of rhetoric » Cf. Arist. Metaph. p. 981. (Berol. Ed.) al iroWal ^fiirdpiai iroLOvffi T^v rex^V^' C ^V*V.~™.- ■- 'V* '-"^*4if^* 18 THE DEFINITION OF LOGIC. DISTINCTION OF ART AND SCIENCE. 19 \m vary with the character of a nation. The eloquence which held a Roman audience spell-bound would have little effect now in moving the minds of men, and would be pronounced artificial and tedious, in spite of the beauty of language and brilliancy of expression. To the practical Spartan the florid eloquence of other tribes of Greece was wearisome in the extreme : the rule of Spartan rhetoric was : Brevity above all things. The art of dyeing cloth or of annealing iron, is always ready to adapt itself indefinitely to new discoveries. The style of paint- ing never remains the same for long. But a science admits of no such variations. The fundamental laws of political economy are the same now as in the days of King Solomon, however great the change that has been introduced into its practical working by the changed conditions of society. Geometry is not only the same in every age and every country, but is unchangeable wherever space and quantity are found. 3. Hence a science proceeds downwards from first principles to the special and individual appli- cations of them. It takes its laws ready made. Even the inductive sciences use experiment and observation as a means of discovering existing laws, not of manufacturing them for themselves. But an art has in general unbounded liberty to make its own laws, so long as it violates no existing law of nature. The art of painting, although it must conform to a certain extent to the laws of perspec- tive and colour, has the greatest possible freedom in all other respects and can encroach even on these. Anything is lawful which will produce a really pleasing picture, even though it may violate some conventional propriety and rules hitherto held sacred. Poetry is equally free, and the purely mechanical arts have more freedom still. 4. But we have not yet reached the central distinction between Art and Science. Aristotle more than once compares them with each other, and gives us the key to their various points of difference. Science, he tells us, is concerned with that which exists already. Art with the production of that which does not as yet exist. ' The end of Science may be practical, but it is never productive, or rather, as soon as it aims at production, it passes into an art. For instance, the Science of Medicine is essentially practical : it teaches the student what are the conditions of perfect health, what means are most serviceable to preserve it, what are the effects upon the human body of this or that acid or alkali, what is the nature and what are the causes of this or that disease. But it is not an art until the practical science is put into practice, with the view of producing certain definite results hitherto non- existent, of producing strength where before there was weakness, health where before there was disease. It then passes out of the character of the Science of Medicine and becomes the Art of Healing. It acquires new characteristics to quahfy it for its new role as an Art. The scientific element is well-nigh forgotten, experience becomes more important, and * 'Eiri