idence 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.

-------------------------------------

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.

INTRODUCTION.