Historical sketch of logic, from the earliest times to the present day

Preface

The following historical sketch of logical science has been written under a conviction, that some such work was needed, both by the general philosophical reader and the student of logic. The theories of reasoning are so numerous, and so diversified in their principles and practical aim, that some general outline of their external history seems, from the antiquity, and acknowledged importance of logical speculations, both called for, and desirable in itself. There is not, so far as I know, any work of this kind in the English language; and the two or three treatises I have met with of a foreign origin, possessing a historical character, have been so brief and limited in their range, that I have not been able to derive much assistance or benefit from them.

Vlll PREFACE.

It has been my constant aim to keep the general principles of the different logical systems I have noticed distinctly before the reader's attention, and to make the historical outline as fruitful as possible of solid and useful information ; valuable especially to those who may be undergoing a course of logical tuition. How far I have succeeded in effecting this object, it does not rest with me to determine.

It has often, in the preparation of this work, been a source of regret, that the limited space I have had allotted to me, prevented me from giving such an extended notice of particular and interesting logical questions as I thought desirable; but brevity was unavoidable where the number of systems and authors so far outstripped the time and means at my disposal. Indeed, five or six such volumes as the present would have been scarcely adequate to do any thing like ample justice to a subject of such great magnitude and diversity of materials. My shortcomings, both in this and in other respects, I am conscious, are numerous and weighty; but if I have, in the humblest degree, succeeded in

PKEFACE. IX barely planting, here and there, a few useful finger-posts to such logical historians as may afterwards follow the same route, I shall feel proud of the achievement, and fully satisfied with the reward it will carry with it.

It was my original intention to enter more fully than I have done into the history of what is called formal logic ; but I soon found that this would extend the work much beyond what was convenient ; and not only so, but that I would infallibly be led into a complete labyrinth of matters of detail, which are comparatively very uninteresting in themselves, whilst the fundamental questions relative to the nature and offices of logic itself are as yet undetermined, and held in abeyance. It is, therefore, chiefly to the philosophical aspect of the science that the contents of this volume refer. I hope, however, to be able, in a short time, to give some account of this technical and formal division of logic, so far as it is connected with the general science of reasoning itself.

Belfast, January 1, 1851.

THE LOGICAL LITERATURE OF GREAT BRITAIN AND THE UNITED STATES OF AMERICA, OF A PHILOSOPHIC AND SYSTEMATIC CAST, FROM THE YEAR 1800 TILL THE PRESENT DAY, . . . . .448

Introduction

It may confidently be asserted, that there is no department of human speculation and inquiry in which so many contradictory opinions are entertained as in the science or art of logic. For the last five-andtwenty centuries, system has followed system in rapid succession ; and one generation of logicians after another have been chiefly occupied in refuting or modifying the principles, and correcting the mistatements of their predecessors. No sooner has a particular logical system obtained a footing in some locality in the republic of letters, and become incorporated with the general routine of philosophical education, than some aspiring and ambitious speculator has called in question its fundamental principles, or subjected its practical rules to supervision and amendment. From Zeno to modern times, every theoretical logician has flattered himself in his day that he had placed logic on a firm basis — not to be disturbed as long as the world lasted. He has flattered himself with the idea, that it was his fortunate lot to chase from the science every vestige of doubt, to reconcile every real and apparent contradiction, and to make, to all future generations,

XY1 INTRODUCTION.

the path of knowledge and science indisputably plain, and of ready and agreeable access.

And the same spirit animates the philosophical logician of the present hour in every direction where his science is known and cultivated. Every speculator has a system of his own with which strangers do not intermeddle. He is the sole champion of his own theory, and the herald of his own fame. He, too, labours under the cheering anticipation that he is putting the finishing stroke to the science, and silencing for ever, throughout the philosophic world, the voice of doubt and contention. Though he may have all the learning of the East, and all the talent of Christendom centred in his own person, yet he knows full well that, apart from his own professorial chair or private study, he will not find a single cultivator of the same science entirely agreeing with him, either on the fundamental principles of logical philosophy, or on the best modes of applying them. But this does not discourage him, nor ruffle the equable current of his self-complacency. He has the advantage over those who have gone before him, hoping unto death the same thing as himself; inasmuch as he reasons that, if there ever is to be a time when the principles of his science are to be known and unalterably fixed, he may be the fortunate instrument in this grand and noble achievement. While there is life there is hope ; and this consideration is sufficient to sustain him in his labours, amidst the mass of disappointment that lies behind him.

The speculative aspects under which logic has appeared in different ages and countries, have not been more checkered and varied than its external fortunes.

INTRODUCTION. XV11

It has at one time revelled in unbounded authority and power, and yet at another been doomed to the bitter humiliation of abject servitude and dependence. It has been the petted child of courts and monarchs, and yet been reviled by the beggar in the street. It was once the art of arts, the science of sciences, and the proudest emblem in the escutcheon of the philosopher. The warrior ventured not to battle without it, nor could the lawyer on the bench, or the theologian in the pulpit, acquit himself with grace unless versed in its canons and rules. Notwithstanding, however, all this power and grandeur, we have witnessed the science scouted from many influential universities ; and, where admitted, it was only on the condition of becoming a humble menial and a willing slave.

In spite, however, of all such reverses, fluctuations, and uncertainties, logic has within it a vigorous principle of vitality. Like the phoenix, it is continually rising from its own ashes. It never allows mankind to wander far nor long, without pressing its claims and obtruding its counsels and admonitions upon them. It must, therefore, have a permanent hold of our sympathies, some fixed root in our nature, or it would have been obliterated long ago from the book of knowledge. Astrology and Alchymy never tantalized human reason so severely. For what can present a greater anomaly to the understanding, than that logic-^calling itself a science ; having chairs in universities set apart for its especial cultivation ; witnessing its professors taking the first rank among the acute and profound of our race ; and pointing, with exulting pride, to more than a thousand distinct treatises on the subject which have

b

XV111 INTRODUCTION.

emanated from tlieir pens within the last three hundred years ; that logic, we say, should, under these circumstances, not be able to furnish two logicians of any country, who can agree in any one common principle of this science, nor be able to state to what particular or general uses it can be applied; must present to the candid mind one of the most striking phenomena in the entire range of human thought. Can any subject, in the whole circle of the sciences, present such a lack of unanimity, or a more cheerless and desponding aspect ? The use of the word logic is almost the only thing which disputants have in common : if we venture a step beyond this, and ask for a definition of what is implied in it, we are instantly stunned with a thousand discordant voices from all parts of the world.

Reverting again to the acknowledged vitality of logical speculations, there must be some adequate and powerful cause for it in the nature and constitution of things. There must be something to which such speculations invariably point, not always possessed, but which has something obvious about it, though difficult to lay hold of and secure. The opposing or antagonistic forces which obstruct our readily seizing the leading truths of logical science, and making them obvious to the understanding of others, must be the result of some settled law of nature, or some extensive range of human feelings and sympathies, which the principles and forms of civil society foster and sustain. Let us then examine, in a sober and serious frame of mind, into the number and nature of these opposing forces, with a view of throwing, if we can, some little light on the great question. Why is it that logic presents such an assem-

INTRODUCTION. XIX

blage of discordant and contradictory opinions and principles ?

In the first place, then, logic, whether of a philosophical or formal caste, is involved in the common difficulties of all questions connected with, or springing out of, mental philosophy. Logic, or the science or art of reasoning, is expressive of, and embodies, a purely intellectual act. This is one of the sources of the haziness which encircles its operations and causes. Every logician must be, to some extent, a metaphysician also ; he deals with mental causes and effects. He must learn the difficult art of looking into his own mind, and scanning, with more or less comprehension and precision, its varied powers and faculties. This is a matter of paramount perplexity to many men ; and to men, too, of even average learning and ability. Here is an obstacle at the first step. The truth soon flashes across the mind of every inquirer, that the noblest part of his being — his intellectual frame — must ever remain partially and imperfectly known. This conviction shakes the confidence of his own judgment, and imparts a doubting spirit to every thing connected with the reflection on his own mind. His examinations and inquiries are personal, and cannot be visibly portrayed or communicated to others. The mode of investigating the world within, is not the same as that which we use for investigating the world without ; and, if we attempt to employ the one mode instead of the other, we shall miserably fail in our object. The tablet of the mind is not like a chessboard, where the unfinished game may be taken up at the point where the last player left it ; for the movements of thought are complicated and subtile, and our

XX INTRODUCTION.

trains of ideas seldom remain fixed or visible to consciousness for any length of time. The lamp of our internal knowledge is for ever passing onwards, and we can only now and then arrest its course, and benefit a little from its light. Every man has to commence a new plan of instruction for himself, and is compelled to leave it in turn, as a broken thread, to whoever comes after him.

Logic being, then, expressive of an intellectual act or operation, it is involved in all that doubt and misconception which appertain to descriptions of mental phenomena generally ; but the science of reasoning, viewed in another light, and in connexion with mind, naturally gives rise to the chief portion of that difference of opinion and judgment so visibly impressed on its past history and present condition. Logic is a science or art hewn or cut out of the mind ; out, as it were, of its very centre, or out of the vital part of its organization. This is a prolific source of disputes, and of divers opposite systems. The question is, how much mentality shall we portion out to the reason, or how little? Some thinkers consider reason, or reasoning, as the entire mental individual — an embodiment of the whole intellectual apparatus ; others, again, limit it to a small fraction of the mind. The question becomes an open and undecided one. The logician and metaphysician are brought into collision. They differ about the boundaries of their respective sciences. The one lays claim to the whole of the domain; while the other is incapable of fixing on the precise portion of it which he wants for his own special purposes. The formal logicians, for example, say, We only want three items ; a

INTRODUCTION. XXI

subject, a copula, and a predicate, and with these we can frame a proposition, and present it under various points of view; with these, in fact, we can display an act of reasoning in all its logical purity and comprehension. This is the only solid and philosophical foundation of logical science. Their opponents, however, remind them that there are more mental phenomena involved in the subject, the copula, and the predicate, and in their formal arrangement into distinct propositions, than what are commonly thought of. If, say the opponents of the strictly formal school, you profess to give an accurate analysis of an act of reasoning, it should be a full and complete analysis ; and if this be given, the result will be, that the regular syllogism will be shewn to embody the distinct co-operation and exercise of a much greater number of mental powers than the formal theory embraces. In the development of every syllogistic process, we recognise the operation of the powers of perception, memory, attention, abstraction, comparison, judgment, and even others ; and in every analysis of such a process of reasoning, it is incumbent we should not only take into consideration all these separate and independent faculties, but also portion out to each its individual share in the general result. Until this is done, there is no full or true analysis of the reasoning faculty. A partial or one-sided analysis is of no use. If logic be solely confined to the development of the laws of thought, considered as thought, it is indispensably requisite that all those laws should be brought out to open day, and admitted as necessary and recognised phenomena in the syllogistic process. Besides, say the anti-formalists, we would like to see a logician's

XX11 INTRODUCTION.

warrant for confining the province of logic within the strict boundary of merely considering the laws of thought as thought? Where is his authority for so doing ? Can he back it by historical evidence, ancient and modern ? Nay, we go beyond even this in our demands ; we require, in conjunction with the authority of historical logic, the philosophical reasons — the regular and formal canons of science — why such and such a thing should be considered as logic rather than any thing else. Let these reasonable conditions be complied with, and then the great question at issue will be in a fair way for a satisfactory solution. For any logician to say that this, and nothing else but this, is pure logic, amounts to nothing. We must have the scientific proofs for the validity of the statement, or it must be comparatively valueless.

On the other hand, again, it is argued, that there must be a line drawn between logic and metaphysics, to preserve the independence of each. When we once admit the consideration of psychological phenomena, and the laws and mutual dependence of the separate powers of the mind, to constitute a determined portion of logic, we, in fact, at once open the door to a vast mass of knowledge, which can be of no use whatever as an element in logical tuition ; but, on the contrary, must tend to obstruct every rational and salutary application of its rules to the understandings of men. We are not to consider here what is theoretically sound, but what is practically possible. Besides, by limiting the definition and offices of logical science to the perception of truth, arising from the consideration of the laws of thought, as thought, we really and virtually do all that is pos-

INTRODUCTION. XX111

sible, from the necessities of the case. To go beyond this, we must either take all objects of human inquiry, and decide on their truth or falsehood, or only some of them. To adopt the first plan is obviously impossible, and to adopt the latter is to make a selection upon no settled or rational principle. The only alternative which is left is, to confine logic strictly to thought, as an act of thinking, and to pass by the particular objects about which the mind thinks.

This is substantially the true position in which the question as to the real objects of logic has been left by the two great rival parties who have taken a distinguished interest in logical discussions from the earliest times to the present hour. The question always arises, How much of the mind shall be appropriated to logic ? The entire history of the science of reasoning, when viewed from a purely intellectual position, is nothing but a practical and running commentary on this question. This has been made the chief point of dispute among all the leading philosophical logicians of every age and country; and the numerous and diversified solutions given of it are conspicuously portrayed in the historical annals of the science.

This, then, is one of the great obstacles in the way of mankind arriving at any thing like a general conclusion as to the limits of logical science. There seems to be no avoiding the difficulty, unless by making the matter in dispute an object of compromise and arrangement. There has been hitherto, and there must always be, mutual concessions among all logicians, from the sheer necessities of their position relative to the subject-matter with which they have to deal.

XXIV INTRODUCTION.

There are, however, other impediments in the way of unanimity as to the principles and modes of teaching logic, arising from causes of a different and more external character than those to which we have just briefly alluded. These obstructions have their principal seat in the influence, direct and indirect, which other departments of human knowledge exercise over logical speculations and systems. Logic has never been studied and taught as an independent science. It has no absolute domain of its own over which to range. In all ages it has professed to deal with truth, whether properly or not we need not stop at the present moment to inquire. Suffice it to say for our present purpose, that its abstract as well as practical aim has been to deal with, touch upon, regulate, and establish the canons of truth in some general or modified shape or fashion. Now, what is truth? A word confessedly of vast import, — embracing, in fact, all that is intellectual, and all that is materially interesting to man — all that is abstract, and all that is practical. It has the heart as well as the head for its basis or foundation. It embodies, in reality, the entire mass of human knowledge, human happiness, and human prospects.

Truth, then, though it has to do with every thing, has not to do with every thing in the same mode and fashion. Truth implies existence, but to mankind it implies much more. It is true that there are trees and houses around me where I now write ; but this truth has no hold of my personality — it is a matter of no concern to me — it conveys neither anxiety, pain, nor pleasure. The truths, for example, of astronomy are highly sublime and interesting, because they can

INTRODUCTION. XXV

be applied to practical purposes in guiding the mariner's frail bark in the trackless ocean, and as being in themselves powerful incentives for elevating the mind to Him by whom the entire universe is maintained ; but take away these immediate and personal effects from astronomical truths, and the whole science would, in fact, be no science at all. And the same thing may be affirmed of every other branch of knowledge. Science of every kind has our internal nature for its basis. Even the abstract truths of mathematics can only be viewed as things having a bare intellectual existence, and can be designated and considered as truths only by virtue of the reflex influence of other principles of a mental and spiritual cast. There is absolutely neither wisdom nor folly where the voice of humanity is not heard.

Such, then, being the nature of truth, with the mysteries of an eternity in the background, we have to inquire how logic, which pretends to have something to do with it, comes to be invested with a peculiar interest, and to be moulded in its character and application by the prevailing influence of other branches of knowledge ? Here a vast field of inquiry presents itself, which it is impossible for us at present to travel over ; but we shall glance at two or three of the most prominent objects in the mental landscape, which may possibly throw some light on the question we have ventured to discuss.

We have a very striking illustration in the writings of the scholastic logicians, and, indeed, from almost every class of writers on mental subjects up to a very recent period of history, of this peculiar mode of appre-

XXVI INTRODUCTION.

hending the nature and offices of all philosophic truth. This is exemplified in the discussions on the nature of being. Every one who has looked into the books of logic and metaphysics of the middle ages, must have recognised the importance attached to this abstract notion of existence. The grand end, however, which it is made to serve as a philosophical instrument of reasoning, is to impart to the mind a right conception of the design of all human knowledge. This being is made to consist of two elements ; namely, goodness and truth. These are its inherent attributes, and they are made the medium of connecting all human investigations with the vital interests of mankind, — that which is good, and that which is true. The entire scope of the discussions springing out of the consideration of this general idea of being, and which have a direct bearing on all science whatever, is, to enforce the conviction on the mind, that all true knowledge must have for its ultimate object the permanent happiness and improvement of mankind; but that these cannot be attained by limiting our views to merely temporal or material expedients.

In the first place, logical systems have uniformly been discussed through the medium of metaphysical theories. Whatever opinions a logician might have on the abstract nature of mind, or on the number and specific character of its separate powers or faculties, these opinions were sure to influence him in his investigations into the reasoning process. There must be a harmony maintained in his general creed at any price. This is strikingly exemplified in the entire history of logical philosophy, from its first dawn in Greece to the

INTRODUCTION. XXY11

present hour. In every age, the mental theories being given, we can determine with scrupulous precision the general phases of logical speculations. And so pointedly is this the case, that all the general terms of classification commonly used to designate theories of the mind, may be applied with the same force and exactness to systems of logic. We have the material, the rationalistic, the eclectic, the transcendental, the theological, the mystical, the sensational, and the common sense theories of logical truth or science, in the same way as we have corresponding theories of mental philosophy and speculation comprehended under these several terms.

And not only is this the case, that logic is greatly and directly influenced by the current doctrines of mental science, but it is also greatly modified and checkered, in its outward arrangements and rules, by the prevailing sentiments and opinions of philosophers on particular questions of metaphysical knowledge. Witness, for example, the unsatisfactory state in which theories of mathematical evidence, of induction, of ^Nominalism and Realism, are at the present moment placed. Nothing can be more opposite and conflicting than the judgments of the philosophers of Europe, at the present moment, on these perplexing, though highly interesting points. Yet all these distinct questions are so closely blended with systems of logic — theoretical, practical, and formal — that no ground can be occupied by any speculator promulgating doctrines on the nature of general reasoning, free from their actual intrusion and influence. These questions lie at the very threshold of logical investigations, and must be disposed of in some

XXVI 11 INTRODUCTION.

fashion or other before the logician is allowed to take a single step in his inquiries.

Independently of this obstacle from mental philosophy itself, we have still other more direct and powerful influences to contend against, in reference to the unity of logical doctrines and tuition. Antagonistic forces of an external character meet us at every turn. Logic having, or professing to have, to do with truth, the watchfulness and jealousy of men are called into a state of activity, whenever the truth of particular departments of knowledge is conceived to be in jeopardy, or likely to be affected in any way or degree. All the interesting and moving questions which engross the feelings and sympathies of the mass of mankind in every country, and which are connected with, or grow out of, the sciences of theology, morals, and politics, have a direct reflex effect upon both the theory and practical application of logical science. It forms an item of secular interest and calculation to the temporal powers of the world, which is never lost sight of. The theologian, the moralist, and the legislator, keep a watchful eye over the use of an instrument which professes to deal with every department of scientific evidence or proof, with every speculative form of thought, and with the application of knowledge to the everyday interests and necessities of human life.

True, the influence of logical systems is not viewed with the same degree of suspicion in all departments of human inquiry. The mathematical and physical sciences, for example, seem removed from any direct logical control. The ingenuity of man may exercise itself here in comparative independence and liberty ;

INTRODUCTION. XXIX and, with some trifling qualifications, he may adopt any theory he pleases. With purely objective knowledge, logic does not come in hostile contact. It is only in the mental and spiritual element that its conflict lies. The moment we pass the boundaries which separate the outer world of matter from the inner world of thought, we tread upon debatable ground, and excite the feelings of human nature in such a way and degree, as they are never seen to be excited in the ordinary philosophical investigations carried on in the pure and physical sciences.

The weighty influence which is thus brought to bear on logical studies, by particular branches of knowledge, arises from the intimate union subsisting between them and the faculty of reasoning generally. Theology, for example, has, in many epochs of her history, imparted the highest degree of interest to logical doctrines, and inspired a reverence and enthusiasm for their cultivation among great masses of people. On the other hand, again, theology often stands in awe of logic, and views all its modes of tuition with jealousy and apprehension. The reason for these opposite states of feeling in religious communities is, that the logical or reasoning powers have a peculiar and powerful influence over the theological element, and may be made to agitate vital and momentous questions to a serious extent. It is the established policy of Christian nations to prevent such occurrences. The action and reaction of theology and logic is strikingly observable in every period of history ; and the mutual sympathy between them, even at this hour, is as active and influential as ever.

XXX INTRODUCTION.

If mankind could be brought to think unanimously on all the fundamental principles of theology, morals, and politics, there would be then some chance likewise for logical unanimity ; but as this is not likely to happen, there must always be great differences of opinion on the principles which should constitute a science of argumentation. Long-established institutions and modes of thinking are always chary of speculative innovations ; for, unless some palpable and immediate advantage presents itself as an infallible result of change, the public mind keeps in the old channels of inquiry and knowledge in which it has been so long accustomed to move, regardless of the bold pretensions of startling novelties.

Logic must, then, I conceive, be doomed to present for ever a variable aspect — to be a system not united or bound together by a series of scientific axioms, susceptible of independent and demonstrative proof, and backed by a rigid and unvarying consequentially ; but rather as constituting a code of rules and judgments, gathered from individual observation in every walk of science, and from every position in which the human mind is placed— partaking, moreover, largely of a prudential and precautionary character. And this has been, in fact, the true form logic has been compelled to assume, particularly within the last three centuries, purely from the necessity of accommodating itself to the progressive and extended range of philosophic thought, and to the constant desire manifested, that all knowledge should be tested by its susceptibility of promoting the moral, religious, and intellectual improvement of individuals and societies. No scientific