ON THE PHILOSOPHY OF DISCOVERY. Cambridge: PRINTED BY C. J. CLAY, M.A. AT THE UNIVERSITY PRESS. ON THE PHILOSOPHY OF DISCOVERY, CHAPTERS HISTORICAL AND CRITICAL; BY WILLIAM WHEWELL, D.D. MASTER OF TRINITY COLLEGE, CAMBRIDGE, AND CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE. INCLUDING THE COMPLETION OF THE THIRD EDITION OF THE PHILOSOPHY OF THE INDUCTIVE SCIENCES. [Illustration: Hand passing torch to hand] ΛΑΜΠΑΔΙΑ ΕΧΟΝΤΕΣ ΔΙΑΔΩΣΟΥΣΙΝ ΑΛΛΗΛΟΙΣ LONDON: JOHN W. PARKER AND SON, WEST STRAND. 1860. The following are the latest editions of the series of works which has been published connected with the present subject: _History of the Inductive Sciences_, 3 Vols. 1857. _History of Scientific Ideas_, 2 Vols. 1858. _Novum Organon Renovatum_, 1 Vol. 1858. _On the Philosophy of Discovery_, 1 Vol. 1860. To the _History of the Inductive Sciences_ are appended two Indexes (in Vol. 1.), an Index of Proper Names, and an Index of Technical Terms. These Indexes, and the Tables of Contents of the other works, will enable the reader to refer to any person or event included in this series. PREFACE The two works which I entitled _The History of the Inductive Sciences_, and _The Philosophy of the Inductive Sciences_, were intended to present to the reader a view of the steps by which those portions of human knowledge which are held to be most certain and stable have been acquired, and of the philosophical principles which are involved in those steps. Each of these steps was a scientific _Discovery_, in which a _new_ conception was applied in order to bind together observed facts. And though the conjunction of the observed facts was in each case an example of logical _Induction_, it was not the inductive process merely, but the _novelty_ of the result in each case which gave its peculiar character to the History; and the Philosophy at which I aimed was not the Philosophy of Induction, but the _Philosophy of Discovery_. In the present edition I have described this as my object in my Title.