tinctions 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 this branch of his subject, it is a duty to acknowledge that for much of it he has been indebted to several important treatises, partly historical and partly philosophical, on the generalities and processes of physical science, which have been published within the last few years. To these treatises, and to their authors, he has endeavored to do justice in the body of the work. But as with one of these writers, Dr. Whewell, he has occasion frequently to express differences of opinion, it is more particularly incumbent on him in this place to declare, that without the aid derived from the
- ↑ In the later editions of Archbishop Whately's "Logic," he states his meaning to be, not that "rules" for the ascertainment of truths by inductive investigation can not be laid down, or that they may not be "of eminent service," that that they "must always be comparatively vague and general, and incapable of being built up into a regular demonstrative theory like that of Syllogism." (Book iv., ch. iv, § 3.) And he observes, that to devise a system for this purpose, capable of being "brought into scientific form," would be an achievement which "he must be more sanguine than scientific who expects." (Book iv., ch, ii, § 4.) To effect this, however, being the express object of the portion of the present work which treat of Induction, the words in the text are no overstatement of the difference of opinion between Archbishop Whately and me on the subject.
