A System of Logic

A System of Logic

This book makes no pretense of giving to the world a new theory of the

intellectual operations. Its claim to attention, if it possess any, is

grounded on the fact that it is an attempt, not to supersede, but to

embody and systematize, the best ideas which have been either promulgated

on its subject by speculative writers, or conformed to by accurate

thinkers in their scientific inquiries.

To cement together the detached fragments of a subject, never yet treated

as a whole; to harmonize the true portions of discordant theories, by

supplying the links of thought necessary to connect them, and by

disentangling them from the errors with which they are always more or less

interwoven, must necessarily require a considerable amount of original

speculation. To other originality than this, the present work lays no

claim. In the existing state of the cultivation of the sciences, there

would be a very strong presumption against any one who should imagine that

he had effected a revolution in the theory of the investigation of truth,

or added any fundamentally new process to the practice of it. The

improvement which remains to be effected in the methods of philosophizing

(and the author believes that they have much need of improvement) can only

consist in performing more systematically and accurately operations with

which, at least in their elementary form, the human intellect, in some one

or other of its employments, is already familiar.

In the portion of the work which treats of Ratiocination, the author has

not deemed it necessary to enter into technical details which may be

obtained in so perfect a shape from the existing treatises on what is

termed the Logic of the Schools. In the contempt entertained by many

modern philosophers for the syllogistic art, it will be seen that he by no

means participates; though the scientific theory on which its defense is

usually rested appears to him erroneous: and the view which he has

suggested of the nature and functions of the Syllogism may, perhaps,

afford the means of conciliating the principles of the art with as much as

is well grounded in the doctrines and objections of its assailants.

The same abstinence from details could not be observed in the First Book,

on Names and Propositions; because many useful principles and distinctions

which were contained in the old Logic have been gradually omitted from the

writings of its later teachers; and it appeared desirable both to revive

these, and to reform and rationalize the philosophical foundation on which

they stood. The earlier chapters of this preliminary Book will

consequently appear, to some readers, needlessly elementary and

scholastic. But those who know in what darkness the nature of our

knowledge, and of the processes by which it is obtained, is often involved

by a confused apprehension of the import of the different classes of Words

and Assertions, will not regard these discussions as either frivolous, or

irrelevant to the topics considered in the later Books.

On the subject of Induction, the task to be performed was that of

generalizing the modes of investigating truth and estimating evidence, by

which so many important and recondite laws of nature have, in the various

sciences, been aggregated to the stock of human knowledge. That this is

not a task free from difficulty may be presumed from the fact that even at

a very recent period, eminent writers (among whom it is sufficient to name

Archbishop Whately, and the author of a celebrated article on Bacon in the

_Edinburgh Review_) have not scrupled to pronounce it impossible.(1) The

author has endeavored to combat their theory in the manner in which

Diogenes confuted the skeptical reasonings against the possibility of

motion; remembering that Diogenes’s argument would have been equally

conclusive, though his individual perambulations might not have extended

beyond the circuit of his own tub.

Whatever may be the value of what the author has succeeded in effecting on

Several criticisms, of a more or less controversial character, on this

work, have appeared since the publication of the second edition; and Dr.

Whewell has lately published a reply to those parts of it in which some of

his opinions were controverted.(2)

I have carefully reconsidered all the points on which my conclusions have

been assailed. But I have not to announce a change of opinion on any

matter of importance. Such minor oversights as have been detected, either

by myself or by my critics, I have, in general silently, corrected: but it

is not to be inferred that I agree with the objections which have been

made to a passage, in every instance in which I have altered or canceled

it. I have often done so, merely that it might not remain a

stumbling-block, when the amount of discussion necessary to place the

matter in its true light would have exceeded what was suitable to the

occasion.

To several of the arguments which have been urged against me, I have

thought it useful to reply with some degree of minuteness; not from any

taste for controversy, but because the opportunity was favorable for

placing my own conclusions, and the grounds of them, more clearly and

completely before the reader. Truth on these subjects is militant, and can

only establish itself by means of conflict. The most opposite opinions can

make a plausible show of evidence while each has the statement of its own

case; and it is only possible to ascertain which of them is in the right,

after hearing and comparing what each can say against the other, and what

the other can urge in its defense.

Even the criticisms from which I most dissent have been of great service

to me, by showing in what places the exposition most needed to be

improved, or the argument strengthened. And I should have been well

pleased if the book had undergone a much greater amount of attack; as in

that case I should probably have been enabled to improve it still more

than I believe I have now done.

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In the subsequent editions, the attempt to improve the work by additions

and corrections, suggested by criticism or by thought, has been continued.

The additions and corrections in the present (eighth) edition, which are

not very considerable, are chiefly such as have been suggested by

Professor Bain’s “Logic,” a book of great merit and value. Mr. Bain’s view

of the science is essentially the same with that taken in the present

treatise, the differences of opinion being few and unimportant compared

with the agreements; and he has not only enriched the exposition by many

applications and illustrative details, but has appended to it a minute and

very valuable discussion of the logical principles specially applicable to

each of the sciences—a task for which the encyclopedical character of his

knowledge peculiarly qualified him. I have in several instances made use

of his exposition to improve my own, by adopting, and occasionally by

controverting, matter contained in his treatise.

The longest of the additions belongs to the chapter on Causation, and is a

discussion of the question how far, if at all, the ordinary mode of

stating the law of Cause and Effect requires modification to adapt it to

the new doctrine of the Conservation of Force—a point still more fully and

elaborately treated in Mr. Bain’s work.