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,,> LECTURES



, / ON



METAPHYSICS AND LOGIC



BY

SIR WILLIAM HAMILTON, BART.

PROFESSOR OP LOGIC AND METAPHYSICS IN THE UNIVERSITY OF EDINBURGH ;

ADVOCATE, A. M. (OXOK.), ETC.; CORRESPOND ni NO MEMBER OF* THE INSTITUTE OF FRANCE ; HONOEAEY

MB1IBER OF TUB AMERICAN ACADKMT OF ARTS AND SCIENCES; AND Of THE

LATIN SOCIETY OF JENA, ETC.



EDITED BY

THE REV. HENRY L. MANSEL, B. D., OXFORD,

AND

JOHN YEITCH, M. A, EDINBURGH.

IN TWO VOLUMES.

VOL. II.
LOGIC.



BOSTON:
GOULD AND LINCOLN,

59 WASHINGTON STREET.

NEW YORK: SHELDON AND COMPANY.
CINCINNATI: GEORGE S. BLANCHARD.

1860.



x -



ON EARTH, THERE IS NOTHING GREAT BUT MAN;
IN MAN, THERE IS NOTHING GREAT BUT 31 I N D .



LECTURES



ON



LOGIC



BY



SIR WILLIAM HAMILTON, BART.

PROFESSOR OF LOGIC AND METAPHYSICS IN THE UNIVERSITY OF EDINBURGH.



EDITED BY .THE

REV. HENRY L. HANSEL, B.D., LL.D.,

WAYNFLETE PEOFESSOR OF MORAL AND METAPHYSICAL PHILOSOPHY, OXFORD,
AND

JOHN VEITCH, M.A.,

PROFESSOR OF LOGIC, RHETORIC. ASP METAPHYSICS. ST. ANDREWS.




BOSTON:
GOULD AND LINCOLN,

59 WASHINGTON STREET.

NEW YORK: SHELDON AND COMPANY.
CINCINNATI: GEORGE S. BLANCHARD.

1860.



AUTHORIZATION.



MEbSRS. GOULD AND LINCOLN, OF BOSTON, UNITED STATES, ARE EXCLUSIVELY AUTHOR
IZED BY ME TO PUBLISH IN AMERICA THE LECTURES, METAPHYSICAL AND LOGICAL,
OP THE LATE SIR WILLIAM HAMILTON, BART.

-JjJ, i 36 / HUBERT HAMILTON.
1C GREAT KING STREET,

EDINBURGH, 14 SEPT., 1838.



A >" D O V F. R :

BLBCTROTYPED AND PRINTED
BY W . F. DRAPER.



E FA.C E.



THE Lectures comprised in the present Volume form
the second and concluding portion of the Biennial
Course on Metaphysics and Logic, which was com
menced by Sir William Hamilton on his election to
the Professorial Chair in 1836, and repeated, with but
slight alterations, till his decease in 1856. The Ap
pendix contains various papers, composed for the most
part during this period, which, though portions of
their contents were publicly taught at least as early
as 1840, were only to a very small extent incorporated
into the text of the Lectures.

The Lectures on Logic, like those on Metaphysics,
were chiefly composed during the session in which they
were first delivered (1837-8); and the statements made
in the Preface to the previous volume, as regards the
circumstances and manner of their composition, are
equally applicable to the present course. In this, as
in the preceding series, the Author has largely availed



VI PREFACE.

himself of the labors of previous writers, many of
whom are but little known in this country. To the
works of the German logicians of the present century,
particularly to those of Krug and Esser, these Lectures
are under special obligations.

In the compilation of the Appendix, some responsi
bility rests with the Editors ; and a few words of ex
planation may be necessary as regards the manner in
which they have attempted to perform this portion of
their task. In publishing the papers of a deceased
writer, composed at various intervals during a long
period of years, and treating of difficult and contro
verted questions, there are two opposite dangers to be
guarded against. On the one hand, there is the dan
ger of compromising the Author s reputation by the
publication of documents which his maturer judgment
might not have sanctioned; and, on the other hand,
there is the danger of committing an opposite injury
to him and to the public, by withholding writings of
interest and value. Had Sir William Hamilton, at any
period of his life, published a systematic treatise on
Logic, or had his projected New Analytic of Logical
Forms been left in a state at all approaching to com
pleteness, the Editors might probably have obtained a
criterion by which to distinguish between those specu
lations which would have received the final imprimatur
of their Author, and those which would not. In the



PREFACE. VII

absence of any such criterion, they have thought it
better to run the risk of giving too much than too
little ; to publish whatever appeared to have any
philosophical or historical interest, without being in
fluenced by its coincidence with their own opinions, or
by its coherence with other parts of the Author s writ
ings. It is possible that, among the papers thus pub
lished, may be found some which are to be considered
rather as experimental exercises than as approved re
sults ; but no papers have been intentionally omitted,
except such as were either too fragmentary to be Intel-,
ligible, or manifestly imperfect sketches of what has
been published here or elsewhere in a more matured
form.

The Notes, in this as in the previous volume, are
divided into three classes. Those printed from the
manuscript of the Lectures appear without any dis
tinctive mark ; those supplied from the Author s Com-
monplace-Book and other papers are enclosed within
square brackets without signature ; and those added by
the Editors are marked by the signature " ED." These
last, as in the Lectures on Metaphysics, are chiefly con
fined to occasional explanations of the text and verifi
cations of references.

In conclusion, the Editors desire to express their ac
knowledgments to those friends from whom they have
received assistance in tracing the numerous quotations



VIII PREFACE.

and allusions scattered through this and the preceding
volume. In particular, their thanks are due to Hubert
Hamilton, Esq., whose researches among his father s
books and papers have supplied them with many val
uable materials ; and to H. W. Chandler, Esq., Fellow
of Pembroke College, Oxford, who has aided them from
the resources of a philosophical learning cognate in
many respects to that of Sir William Hamilton himself.



C O ]Sf T E ]XT T S .



LECTURE I.

INTRODUCTION.

PAGE

LOGIC I. ITS DEFINITION, 1



LECTURE II.

LOGIC I. ITS DEFINITION HISTORICAL NOTICES OF OPINIONS

REGARDING ITS OBJECT AND DOMAIN II. ITS UTILITY, . 14



LECTURE III.

LOGIC - II. ITS UTILITY III. ITS DIVISIONS SUBJECTIVE AND

OBJECTIVE GENERAL AND SPECIAL, 28



LECTURE IV.

LOGIC III. ITS DIVISIONS PURE AND MODIFIED, ... 41

LECTURE V.

PURE LOGIC.

PART I. STOICHElOLOGY. SECTION I. NOETIC. ON THE FUN
DAMENTAL LAWS OF THOUGHT THEIR CONTENTS AND

HISTORY, 52

B



X CONTENTS.

LECTURE VI.

PAGE

THE FUNDAMENTAL LAWS OF THOUGHT THEIR CLASSIFICA
TION AND IMPORT, 69



LECTURE VII.

SECTION II. OF THE PRODUCTS OF THOUGHT. I. ENNOEMATIC
OF CONCEPTS OR NOTIONS A. OF CONCEPTS IN GEN
ERAL, 83



LECTURE VIII.

ENNOEMATIC A. OF CONCEPTS IN GENERAL ; B. IN SPECIAL.

I. THEIR OBJECTIVE RELATION QUANTITY 93



LECTURE IX.

ENNOEMATIC. B. OF CONCEPTS IN SPECIAL. - II. THEIR SUB
JECTIVE RELATION QUALITY, 111



LECTURE X.

ENNOEMATIC. - IMPERFECTION OF CONCEPTS, 121

LECTURE XI.

ENNOEMATIC. -III. RECIPROCAL RELATIONS OF CONCEPTS. - A.
QUANTITY OF EXTENSION - SUBORDINATION AND COORDI
NATION, 132



CONTENTS. XI

LECTURE XII.

PAGE

ENNOEMATIC. III. RECIPROCAL RELATIONS OF CONCEPTS. B.

QUANTITY OF COMPREHENSION, 150



LECTURE XIII.

II. APOPHANTIC, OR THE DOCTRINE OF JUDGMENTS. JUDG
MENTSTHEIR NATURE AND DIVISIONS, 159



LECTURE XI Y.

APOPHANTIC. JUDGMENTS THEIR QUALITY, OPPOSITION, AND

CONVERSION, 175



LECTURE XV.

III. DOCTRINE OF REASONINGS. REASONING IN GENERAL. -
SYLLOGISMS THEIR DIVISIONS ACCORDING TO INTERNAL
FORM, 180



LECTURE XVI.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO INTERNAL FORM. A. SIMPLE CATEGORI
CAL. I. DEDUCTIVE IN EXTENSION, ..... 206



LECTURE XVII.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO INTERNAL FORM. A. SIMPLE CATEGORI
CAL. II. DEDUCTIVE IN COMPREHENSION. III. INDUCTIVE
IN EXTENSION AND COMPREHENSION. B. CONDITIONAL
DISJUNCTIVE, 221



XII CONTENTS.

LECTURE XVIII.

PAGE

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO INTERNAL FORM. B. CONDITIONAL HY
POTHETICAL AND HYPOTHETICO-DISJUNCTIVE, ... 239



LECTURE XIX.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO EXTERNAL FORM. A. COMPLEX EPI-
CHEIREMA AND SORITES, 257



LECTURE XX.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO EXTERNAL FORM. B. DEFECTIVE EN-
THYMEME. C. REGULAR AND IRREGULAR FIGURE AND
MOOD FIRST AND SECOND FIGURES, 275



LECTURE XXI.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO EXTERNAL FORM. THIRD AND FOURTH
FIGURES, 294



LECTURE XXII.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS
ACCORDING TO EXTERNAL FORM. C. REGULAR AND IR
REGULAR. FIGURE - REDUCTION, 306



LECTURE XXIII.

DOCTRINE OF REASONINGS. SYLLOGISMS THEIR DIVISIONS

ACCORDING TO VALIDITY. FALLACIES, 321



CONTENTS.

LECTURE XXIV.

PAGE

PURE LOGIC.

PART II. METHODOLOGY. SECTION I. METHOD IN GENERAL. -
SECTION II. METHOD IN SPECIAL, OR LOGICAL METHODOL
OGY. I. DOCTRINE OF DEFINITION, 335



LECTURE XXV.

METHODOLOGY.
LOGICAL METHODOLOGY. II. DOCTRINE OF DIVISION, . . 350

LECTURE XXVI.

LOGICAL METHODOLOGY. III. DOCTRINE OF PROBATION, . . 360

LECTURE XXVII.

MODIFIED LOGIC.

PART t MODIFIED STOICHEIOLOGY. SECTION I. DOCTRINE OF

TRUTH AND ERROR. TRUTH ITS CHARACTER AND KINDS, 376

LECTURE XXVIII.

MODIFIED STOICHEIOLOGY.

SECTION I. DOCTRINE OF TRUTH AND ERROR. SECTION II. ER
ROR ITS CAUSES AND REMEDIES. A. GENERAL CIRCUM
STANCESSOCIETY, 387

LECTURE XXIX.

ERROR ITS CAUSES AND REMEDIES. A. GENERAL CIRCUM
STANCES SOCIETY. B. AS IN POWERS OF COGNITION,
FEELING, AND DESIRE. I. AFFECTIONS PRECIPITANCY -
SLOTH HOPE AND FEAR SELF-LOVE, . . . . . 397



XIV CONTENTS.

LECTURE XXX.

PAGE

ERROR ITS CAUSES AND REMEDIES. B. AS IN THE COGNI
TIONS, FEELINGS, AND DESIRES. II. WEAKNESS AND DIS-
PROPORTIONED STRENGTH OF THE FACULTIES OF KNOWL
EDGE, 411



LECTURE XXXI.

ERROR ITS CAUSES AND REMEDIES. C. LANGUAGE. D. OB
JECTS OF KNOWLEDGE, .... 432



LECTURE XXXII.

MODIFIED METHODOLOGY.

SECTION I. OF THE ACQUISITION AND PERFECTING OF KNOWL
EDGE. I. EXPERIENCE. A. PERSONAL : OBSERVATION -
INDUCTION AND ANALOGY, 441



LECTURE XXXIII.

OF THE ACQUISITION AND PERFECTING OF KNOWLEDGE. I.
EXPERIENCE. B. FOREIGN : ORAL TESTIMONY ITS CRED
IBILITY, 457



LECTURE XXXIV.

OF THE ACQUISITION AND PERFECTING OF KNOWLEDGE. I.
EXPERIENCE. B. FOREIGN: RECORDED TESTIMONY AND
WRITINGS IN GENERAL. II. SPECULATION, .... 468



LECTURE XXXV.

OF THE ACQUISITION AND PERFECTING OF KNOWLEDGE. III.
COMMUNICATION OF KNOWLEDGE. A. INSTRUCTION -
ORAL AND WRITTEN. B. CONFERENCE DIALOGUE AND
DISPUTATION, 478



CONTENTS. XV

APPENDIX.

PAGE

I. THE CHARACTER AND COMPREHENSION t)F LOGIC A FRAG
MENT, * 495

II. GENUS OF LOGIC, 498

III. DIVISIONS, VARIETIES, AND CONTENTS OF LOGIC, . . 501

IV. LAWS OF THOUGHT, 506

V. NEW ANALYTIC OF LOGICAL FORMS GENERAL RESULTS

FRAGMENTS.

I. EXTRACT FROM PROSPECTUS OP "ESSAY TOWARDS A NEW

ANALYTIC OF LOGICAL FORMS/ 509

II. LOGIC, ITS POSTULATES, 512

III. QUANTIFICATION OF PREDICATE, IMMEDIATE INFER
ENCE, CONVERSION, OPPOSITION, .... 514

IV. APPLICATION OF DOCTRINE OF QUANTIFIED PREDICATE

TO PROPOSITIONS, 529

V. APPLICATION OF DOCTRINE OF QUANTIFIED PREDICATE

TO SYLLOGISMS, 536

VI. OBJECTIONS TO THE DOCTRINE OF A QUANTIFIED PRED
ICATE CONSIDERED, 539

VII. HISTORICAL NOTICES OF DOCTRINE OF QUANTIFIED

PREDICATE, . 546

VI. CANONS Of SYLLOGISM; GENERAL HISTORICAL NOTICES
AND CRITICISM.

A. HISTORICAL NOTICES.

I. FUNDAMENTAL LAWS OF SYLLOGISM QUOTATIONS, . 559

II. FUNDAMENTAL LAWS OF SYLLOGISM REFERENCES, . 575

III. ENUNCIATIONS OF THE HIGHER LAWS OF SYLLOGISM, . 576

IV. OBJECTIONS TO THE DICTUM DE OMNI ET NULLO, . 578

V. GENERAL LAWS OF SYLLOGISM IN VERSE, . . . 578

VI. SPECIAL LAWS OF SYLLOGISM IN VERSE, . . . 579

B. CRITICISM.

I. CRITICISM OF THE SPECIAL LAWS OF SYLLOGISM, . . 579

II. LAWS OF SECOND FIGURE, .... . 582

HI. AUTHOR S SUPREME CANONS OF CATEGORICAL SYLLO
GISMS, 583

IV. ULTRA-TOTAL QUANTIFICATION OF MIDDLE TERM, . 584



XVI CONTENTS.

VII. INDUCTION AND EXAMPLE.

PAGE

I. QUOTATIONS FROM AUTHORS, 589

II. MATERIAL INDUCTION, 597

VIII. HYPOTHETICAL AND DISJUNCTIVE REASONING IMMEDI

ATE INFERENCE.

I. AUTHOR S DOCTRINE FRAGMENTS, 598

II. HISTORICAL NOTICES, 612

IX. SORITES, 619

X. SYLLOGISM.

I. ITS ENOUNCEMENT ANALYTIC AND SYNTHETIC ORDER

OF PREMISES.

(a) ENOUNCEMENT OF SYLLOGISM, .... 621

(6) ORDER OF PREMISES, 624

II. FIGURE UNFIGURED AND FIGURED SYLLOGISM.

(1853) (a) CONTRAST AND COMPARISON OF THE VARI
OUS KINDS OF FORMAL SYLLOGISM DIFFERENCE OF



FIGURE ACCIDENTAL,

(6) DOUBLE CONCLUSION IN SECOND AND THIRD FIG-



626



URES, 627

III. HISTORICAL NOTICES REGARDING FIGURE OF SYLLOGISM, 632

IV. SYLLOGISTIC MOODS.

I. DIRECT AND INDIRECT MOODS, .... 658

II. INDIRECT MOODS OF SECOND AND THIRD FIGURES, 663

III. NEW MOODS NOTES UPON TABLE Otf SYLLOGISMS, 665

XL LOGICAL NOTATION.

I. LAMBERT S LINEAR NOTATION, 667

II. NOTATION BY MAASS, 669

III. AUTHOR S SCHEME OF NOTATION.

NO. I. LINEAR, 670

NO. II. UNFIGURED AND FIGURED SYLLOGISM, . . 673

NO. III. FIGURED SYLLOGISM TABLE OF MOODS, . 678



UNIVERSITY




LECTURES ON LOGIC



LECTURE I.*

INTRODUCTION.
LOGIC I. ITS DEFINITION.

GEXTLEMEN : We are now about to enter on the consideration
of one of the most important branches of Men-
Logic proper, mode tal Philosophy, the science which is conver-

in which its considera- ^ ^ fa L f Th ht j^ bef

tion ought to be con- m &

ducted. commencing the discussion, I would premise a

word in regard to the mode in which it ought

to be conducted, with a view to your information and impixr ement.
The ffreat end which every instructor ousftt to

End of instruction. . * . .

propose in the communication of a science, is, to
afford the student clear and distinct notions of its several parts, of
their relations to each other, and to the whole of which they are
the constituents. For unless he accomplish this, it is of compara
tively little moment that his information be in itself either new or
important; for of what consequence are all the qualities of a doc
trine, if that doctrine be not communicated? and communicated
it is not, if it be not understood.

But in the communication of a doctrine, the methods to be fol
lowed by an instructor who writes, and by an
Methods of written i nstmctor wno sp eaks, are not the same. They

and oral instruction . ~

different. are m * act to a certam extent, necessarily dif

ferent : for, while the reader of the one can al
ways be referred back or forward, can always compare one part of a

* The first seven Lectures of the Metaphysical Course (Lectures on Metaphysics, pp.
100) were delivered by Sir William Hamilton as a General Introduction to the
Course of Logic proper. ED.

1



2 LOGIC. LECT. I.

book with another, and can always meditate at leisure on each step
of the evolution ; the hearer of the other, on the contrary, must at
every moment be prepared, by what has preceded, to comprehend
at once what is to ensue. The oral instructor has thus a much more
arduous problem to solve, in accomplishing the end which he pro
poses. For if, on the one hand, he avoid obscurity by communicat
ing only what can easily be understood as isolated fragments, he is
intelligible only because he communicates nothing worth learning :
and if, on the other, he be unintelligible in proportion as his doc
trine is concatenated and systematic, he equally fails in his attempt ;
for as, in the one case, there is nothing to teach, so, in the other,
there is nothing taught. It is, therefore, evident, that the oral in
structor must accommodate his mode of teaching to the circum
stances under which he acts. He must endeavor to make his audi
ence fully understand each step of his movement before another is
attempted ; and he must prepare them for details by a previous sur
vey of generals. In short, what follows should always be seen to
evolve itself out of what precedes. It is in consequence of this
condition of oral instruction, that, where the development of a sys
tematic doctrine is attempted in a course of Lec-
use of Text-book in tm Jt ig usual for the ] ecturer to facilitate the

a systematic course of , , . . ., , . .t- A .

L ectures labor to Jus pupils and himself, by exhibiting in

a Manual or Text-book the order of his doctrine
and a summary of its contents. As I have not been able to prepare
this useful subsidiary, I shall endeavor, as far as possible, to supply
its want. I shall, in the first place, endeavor always to present you
with a general statement of every doctrine to
be ex P lained > before descending to the details
of explanation ; and in order that you may be
insured in distincter and more comprehensive notions, I shall, where
it is possible, comprise the general statements in Propositions or
Paragraphs, which I shall slowly dictate to you, in order that they
may be fully taken down in writing. This being done, I shall pro
ceed to analyze these propositions or paragraphs, and to explain
their clauses in detail. This, I may observe, is the method followed
in those countries where instruction by prelection is turned to the
best account; it is the one prevalent on the Continent, more es
pecially in the universities of Germany and Holland.

In pursuance of this plan, I at once commence by giving you,
as the first proposition or paragraph, the following. I may notice,
however, by parenthesis, that, as we may have sometimes occasion
to refer articulately to these propositions, it would be proper for
you to distinguish them by sign and number.



LECT. I. LOGIC. 3

The first paragraph, then, is this :

IT I. A System of Logical Instruction consists of Two Parts,
1, Of an Introduction to the science;

Par. I. Ofwhatasys- ^ Q f g, Q f J) octrine constituting the
tem of Logic consists. *

Science itself.
These, of course, are to be considered in their order.

^ II. The Introduction to Logic should afford answers to the
following questions : i. What is Logic ? ii.

Par. II. Tne Intro- . . y j ? ... Wfa . p. .



duction to Logic.

ions? iv. What is its History? and, v.
What is its Bibliography, that is, what are the best books upon
the subject?

In regard to the first of these questions, it is evident that its
answer is given in a definition of Logic. I therefore dictate to
you the third paragraph.

^T III. What is Logic? Answer Logic
Par. in. i. Deiini- j } Science of the Laws of Thought as

tion of Logic.

Thouht.






This definition, however, cannot be understood without an ar

ticulate exposition of its several parts. I there-
Explication. x . .

lore proceed to this analysis and explanation,

and shall consider it under the three following heads. In the first,
I shall consider the meaning, and history, and synonyms of the
word Logic. In the second, I shall consider the Genus of Logic,
that is, explain why it is defined as a Science. In the third, I shall
consider the Object-matter of Logic, that is, explain to you what
is meant by saying, that it is conversant about the Laws of Thought
as Thought.

First, then, in regard to the significance of the word. Logic, you
are aware, is a Greek word, Aoyuoj ; and Aoyuo},

1. The word Logic vi $ \ T 1

like ypa/x/xaruo), prjropiKr), TTOIT/TI/O), otaAe/CTi/oy, I need

hardly tell yon, is an adjective, one or other of
the substantives eTmm^oy, science, re^yrj, art, or Tr-pay^u/rem, study, or
rather matter of study, being understood. The term \oyiKrj, in this
special signification, and as distinctly marking out a particular sci
ence, is not so old as the constitution of that science itself. Aris
totle did not designate by the term Aoyi*??, the science whose doc-



4 LOGIC. LECT. I.

trine he first fully developed. He uses, indeed, the adjective AoyiKos
in various combinations with other substantives.
Thus I find in his Physics, Aoyt/o) cwropia, 1 in

his Rhetoric, XoyLKal Swxepei ai, 2 in his Metaphysics, AoyiKas drroSeif-

ctSj 3 _ j n k^ posterior Analytics, evta Aoyt/ca, 4 in his Topics, Aoyi-

KOV <rrp6pXr}p.a. 5 He, likewise, not unfrequently makes use of the

adverb AoyiKws. 6 By whom the term Aoyuo} was first applied, as the

word expressive of the science, does not appear. Boethius, who

flourished at the close of the fifth and commencement of the sixth

century, says, in his Commentary on the Topics of Cicero] that the

name of Logic was first given by the ancient

Ancient Peripatetics. p eripatetics . i n the works of Alexander of Aph-

Aiexander of Aph- ro( jisias, the oldest commentator we possess on

the works of Aristotle (he flourished towards

the end of the second century), the term Aoyi/oj, both absolutely

and in combination with irpaynareia, etc., is frequently employed ; 8

and the word is familiar in the writings of all the subsequent Aris

totelians. Previously, however, to Alexander, it is evident that

Aoyuoj had become a common designation of the

science; for it is once and again thus applied

by Cicero. 9 So much for the history of the word Logic, in so far

as regards its introduction and earlier employment. We have now

to consider its derivation and meaning.

It is derived from Ao yo?, and it had primarily

(b) its derivation and the same latitude and variety of signification as
meaning its original. What then did Xoyos signify? In

Twofold meaning of , , . p i j T<-

Ao/ os Greek this word had a twofold meaning. It

denoted both thought and its expression; it was

equivalent both to the ratio and to the oratio of the Latins. The

l B. iii. c. 3. "E X < 5 fcropfoi Xoy^v 6 E " * AnaL ?*? L 21 82j Phys ViiL 8;

Dubitationem quse non e rerum singularium Mtap/i., vi. 4. 17 rxi. 1.

(physicarum) contemplatione, sed e ratiocina- 7 L> sub imt - ~ ED

tione sola orta est." Waitz, ad Arist. Org., 8 See, especially, his commentary on the

vol. ii. p- 354. Logical and dialectical reason- Frior Analytics, f. 2 (SchoKa, ed, Brandis, p.

ing in Aristotle mean the same thing,-viz., 141), where he divides i \oyncr, re K al cr.A-

reasoning founded only on general principles X7r *PVI" into four branches



of probability, not on necessary truths or on or, , , and

special experiences. -EB. (ro^arr^. Here Logic is used in a wider

2 This expression occurs not in the Rhetoric, sense than the adjective and adverb bear m
but in the Metaphysics, B. iii. (iv.) c. 3, and B. Aristotle, while the cognate ******* re
xiii. (xiv.) c. 1 In the Rtetoric we find the tains its original sagn Ration. - Lr>
expression Xoyoi <ruAAo W o<, B. i. c. 1. 9 See De F.nious . ,; Tusc Qaas iv. 14

* Cicero probably borrowed this use

term from the Stoics, to whose founder, Zeno,

3 B. xiii. (xiv.) c. 1. Cf. De Gener. Arum., Laertiug (yii 39) agcribes the origin of the
ii. 8. ED. division of Philosophy into Logic, Physics,

4 B. i. c. 24 Eo. an( j Ethics, sometimes erroneously attributed

5 B. v. c. 1. ED. to Plato. ED.



LECT.I. LOGIC. 5

Greeks, in order to obviate the ambiguity thus arising from the
confusion of two different things under one expression, were com
pelled to add a differential epithet to the common term. Aristo

tle, to contradistinguish Aoyos, meaning thought,
HOW expressed by f ronl Xoyos, meaning speech, calls the former TOV

ecro), TOV Iv rfj i/or^, that within, that in the
mind; and the latter, iw w, that without}- The same distinc

tion came subsequently to be expressed by the

Aoyos evSta^eros, for thought, the verbum mentis /
and by Ao yos 7rpo</>opiKos, for language, the verbum oris. 2 It was nec
essary to give you this account of the ambiguity of the word Aoyos,
because the same passed intoats derivative Aoyi/oj ; and it also was
necessary that you should be made aware of the ambiguity in the
name of the science, because this again exerted an influence on the
views adopted in regard to the object-matter of the science.

But what, it may be asked, was the appellation of the science

before it had obtained the name of Logic? for,
Appellations of the ag j haye s ^ t j ie a oc trine had been discrimi-

science afterwards ... , . , / .

called Logic. nated, and even carried to a very high perfection,

before it received the designation by which it is
now generally known. The most ancient name for what was sub
sequently denominated Logic, was Dialectic. But this must be
understood with certain limitations. By Plato, the term dialectic is
frequently employed to mark out a particular section of philosophy.
But this section is, with Plato, not coextensive with the domain of
Logic ; it includes, indeed, Logic, but it does not exclude Metaphysic,
for it is conversant not only about the form, but about the matter



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