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A New Logic.

THE LANCET.

z<9Jvz’6LY.- S-lTUItDI; 11.1’ 1012.

LOGIC is defined by JOHN STUART MILL as the art of

correct thinking and the science of the conditions of correct

thinking, and we may accept this definition as at least

expressing with sufficient accuracy the meaning which weattach to the word in ordinary speech. And as correct

thinking is the instrument by which man has created

those other arts and sciences that have given him his vastcontrol over the forces of nature, it would seem onlyreasonable to suppose that the remarkable results which the

human mind has achieved in these several directions should

imply a corresponding development of this fundamental

science 0-F logic. So far, however, is this anticipation frombeing realised that the advancement of knowledge has

coincided, not with an increasing cultivation, but with an

increasing neglect of this study, so that to the modern

investigator in any field of science it would appear little

less than an extravagance were anyone to suggest that

he should school his mind and guide his practice bythe principles and methods which logicians expoundin the classical text-books. That logic should have

come to be regarded in this way is as regrettable.-asit is surprising ; for, since correct thinking is by no

means so easy and so natural a process that the

mind can be safely trusted to perform it instinctively,it is obviously to be desired that the principles which

govern such thinking, and the methods by which effect is

given to these principles, should be definitely ascertained andclearly foromlated&mdash;that they should, in short, be reduced toscientific system. This is what logic purports to do, but itdoes it, unfortunately, with so little success that in practicethe scientdnc inquirer prefers as a rule to dispense altogetherwith its aid and to trust, faute de mieux, to the exertions ofhis own undisciplined thinking ; in the problems with whichhe has to even the methods that he works out, often ina rough and haphazard way according to the occasions of his

argument, are, he feels, of more service to him than the

mles of f!"L0:e3sional logic. How, then, is this attitude of

mind to be explained, and if it finds its justification in the

present state of logic, is there any remedy for what must be

recognised as a real hindrance to the progress of science ’!

’These are the questions which Dr. MERCIER has set himself toanswer in his 1, -N-e w Logic, " and we may say at once that inthe somewhat formidable task which he has undertaken he

has achieved what even his most hostile critics may admit to

be a very large measure of success.Dr. MERGER’S thesis is that traditional logic, the logic of

the schools, is a survival of the Dark Ages, and that its

1A New Logic. By Charles Mercier, M.D.Lond. London: WilliamHeinemann. 1912. Pp. 422. Price 10s. net.

whole system is insufficient, defective, and erroneous from

beginning to end ; its analysis of the proposition is faulty ;its doctrines of quantity and quality are wrong ; its doctrine

of the syllogism is artificial and mistaken. Nor does the

inductive school fare much better at his hands; by its

partial acceptance of the deductive scheme of traditional

logic it has run, he asserts, into the same errors, and it hasfurther failed even to recognise the possibilities of develop-ment inherent in its own principle. Of course, in this

destructive part of his task Dr. MERCIER adopts with entirefrankness the position of the prose0uting counsel, and it is

possible that this attitude may sometimes lead him to over-state his case and to leave out of account some extenuatingcircumstances that might be urged in favour of the pro-

fessional logician. It is doubtless for this reason, and also,

perhaps, from an instinctive feeling of pity for the un-

fortunate victims of Dr. MERCIER’S exquisite but mercilesssatire, that the reader is likely to find his interest more keenlyand more pleasurably aroused by the constructive side of theauthor’s thesis. For, as is implied in the title of the work,Dr. MERCIER’S aim is not merely to demolish the obsolete andfutile system which usurps the name of logic; that is

only a preliminary to his main task of setting up a

new logic which shall supply the defects and correct the

errors of the old. And the new logic which he propoundscertainly does possess at all events a considerable share

of the merits which its author claims for it. Obviously, inrelation to such a subject as logic a writer cannot be expectedto discover principles and methods that are entirely novel ;the originality of his work, therefore, is not to be sought inthe amount of absolutely new material which he brings to

light, but in the capacity which he shows for arranging theold material in new and better ways. And Dr. MERCIER’S

arrangement of logical methods, as compared with the

arrangements of his predecessors, has great advantages.We may specially single out as instances of his manner

at its best, his treatment of the distinction between

deductive and inductive reasoning, between the argument/oilex posteciato and the a’ffj1Ul1entum in oraateria. The separa-tion of these two systems, though indicated by MILL, has

certainly lacked adequate recognition in treatises of logic ;and it is one of the distinctive merits of Dr. MERCIER’S

work that he has made ’good this omission and has

fully elaborated the differences in nature, scope, and

object between the deductive process, concerned onlywith the inferences that can be drawn from postulatedpropositions irrespective of the truth or falsity of such

propositions, and the inductive process which rests on

the appeal to experience, and in which, consequently, tLematerial truth of the propositions is vital. To these modes cf

reasoning Dr. MERCIER adds a third-the process of analogyin the Aristotelian sense of the comparison of ratios. ThEse

three methods, though in so far related that they spring froma common root in the fundamental process of comparison,are discussed as completely distinct and discriminable ;they differ altogether in range and object, they are regulatedby different canons, and they are vitiated by differentfallacies. And it is one of the strongest points that can bemade in support of Dr. MERCIER’s system that it providesa simple and complete scheme of classification in which

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these canons and the related fallacies fall into their placeswith an admirable appearance of naturalness. In reality, ofcourse, we do not employ any one method of reasoning tothe exclusion of the others ; all, or nearly all, argument, onthe contrary, involves the frequent alternation of the several

processes ; and it is just this association of the different

methods in composite reasoning that makes the recognitionof their distinctive uses and dangers so essential to clearnessof thinking.

It is a recommendation of the soundness of Dr. MERCIER’S

views that this most interesting volume bears very clearly the

imprint of the author’s professional habit of mind. For it is

peculiarly fitting that a treatise on logic should be written bya physician. He, more than other men, must deal with

concrete problems in which errors of reasoning may bringswift and disastrous results, and in such problems the rulesof closet logicians will be of small help. On the other hand,these problems are too complex and too intricate to allow him Ito dispense with the aid of organised reasoning methods ; hecannot therefore adopt the merely contemptuous attitude ofthe practical man who sees no need for anything more thanthe ready processes that his mother wit provides for the

simpler issues of everyday life. And for the same reason,

we may add, it is peculiarly fitting that Dr. MERCIER’S pro-fessional colleagues should study this work, and if they arenot entirely satisfied as to the value of the logical methodswhich it inculcates they may be recommended, in conformitywith the ancient rule, to try the virtue of these methods onthe opinions and diagnoses from which they dissent. In

saying this, however, we would not be understood to

suggest that Dr. MERCIER’s work is narrow in its appeal.It is, on the contrary, as free from the pedantry of

medicine as from the pedantry of academic logic, and itis written, moreover, with all that directness and lucidity of

style which invariably distinguish Dr. MERCIER’s work, andwhich are seen to peculiar advantage in dealing with such a

subject as logic. The author is to be congratulated on

having produced a volume which, in addition to its other

merits, has a quality that is quite exceptional in treatisesof logic-the quality of being thoroughly interesting and

even, if we may venture to use the word, thoroughlyamusing.

Medicine and the Public.THE Reports of the Poor-law Commission, together with

legislative measures such as the Midwives Act and especiallythe National Insurance Act with all its ramifications which

touch the community at every point and the medical pro-fession more perhaps than any other portion of the populace,have given rise to much writing on the all-important questionof the relations between the members of the medical pro-fession and their fellow citizens. Some of this output hasbeen of high literary quality, some has not; some of thestatements have been accurate and some have been pre-

judiced. The most recently published work of this kind

which has come before us, entitled "The Doctor and the

People," belongs to the better category. 1In this book the author has given in a set of eminently

1 The Doctor and the People. By H. de Carle Woodcock. London:Methuen and Co., Limited. Pp. 312. Price 6s. net.

readable essays much food for thought both to the lay andto the professional reader, and its digestion should promotea healthy feeling that all citizens, both those who want

medical assistance and those who cffer it, should have a

common object. Mr. WOODCOCK writes with a first-hand

knowledge of his subject, for as a general practitioner in a

large manufacturing town and as a former Poor-law medicalofficer he has had varied experience of practice. And he

preaches the doctrine which the medical profession in this

country, ever since its organisation as a profession, has been

preaching, and for the last 40 years with much clearness.This doctrine all Governments have acknowledged to be true,although no politician has yet arisen with enough grip ofthe situation to apply the doctrine to its fulness. It is the

old doctrine of prevention instead of cure, a doctrine the

truth of which the public is but slowly beginning to realise.To the public, even as yet to the more educated section

thereof, a " doctor " is still a man who can give them some-

thing to remove pain or discomfort. They have for the most

part no ideas on hygiene except as a routine to deal with illswhich have become prominent, or on moderate living exceptas something to be practised before a physical breakdownoccurs in themselves, or before they perpetuate evil in their

progeny. The poor go the round of the hospitals and spend a

large portion of a hardly earned wage upon quack medicines ;the rich live in a world of amusement and stress, and whenthe season is over fly to correct their excesses at some homeor Continental watering-place. The need for forethought,for self-denial before the actual necessity occurs, suggests.itself to the public at neither end of the social scale.

Mr. WOODCOCK believes that the solution of all the varyingproblems affecting medical men in their relations with the

public, and, as a natural corollary, of all the defaults in

public medical service, is to be found in the establishment

)f a State Medical Service; but he is aware that such a

service, run on the cheap as regards the workers and in anxtravagant manner as regards the taxpayers, such as is thease at present with many State-paid services, could be no

blessing to anyone, even if the desirability of a State MedicalService were conceded. " It is not," he says, " the cultured

professional man now writing glibly on State-paid oae:)ialdomwho will put our necks under the yoke ; it will be our

new masters. There is grave reason to fear that our

conquerors, the people, prefer quacks to doctors ; they areready to believe without question those who say that a medi-cine or a treatment will do what in truth it cannot do.......What they want from us is often not in reality our

best work and many of them do not want to pay for it." A.

State-paid official in a medical service of this kind, he says,"will end in poorer wages for harder work, and the warningis certainly a timely one. Up to now the tendency of theState has been to lay burden after burden upon the back ofthe medical profession, accompanied sometimes by a small

remuneration, sometimes by none as under the Midwives Act,sometimes not only by none but with a penalty attached for

non-performance, as under the Notification of Births Act.

The motto of this valuable piece of legislation as far as themedical profession is concerned might well run-

The Jew shall have all justice, soft-no haste,He shall have nothing but the penalty.

The future of the medical profession and of its relations to