Berkeley: Principles of Human Knowledge: Text and Critical Essays (review)

510 HISTORY OF PHILOSOPHY John Pecham and the Science o[ Optics. Edited with an introduction, English translation, and critical notes by David C. Lindberg. (Madison: The University of Wisconsin Press, 1970. Pp. xvii + 300. $15) John Pecham's Perspectiva communis, composed during the 1270's, was the most popular medieval treatise on optics. Relying heavily on Alhazen's (c. 965-1039) Perspectiva , Pecham's work is still a fine introduction both to the influential ideas of Alhazen and to the science of optics in the thirteenth century. Pecham was closely associated with an active circle of thirteenth-century writers on optics--Roger Bacon, Robert Grosseteste, and Witelo--and his Perspectiva communis provides the modern reader with an elementary introduction to the problems, theories, and assumptions of this important school of opticians. The work is concerned with the standard topics considered in medieval optics: the theory of vision, explained in terms of the multiplication of species: the nature and propagation of light; reflection; and refraction. Although Pecham's book is primarily concerned with technical problems in optics, it also bears on questions in theology and philosophy. The science of optics in the middle ages was regarded as bearing directly on certain metaphysical problems, especially the question of the infusion of grace which was a process considered analogous to the multiplication of visible species. In his lucid introduction, Professor Lindberg places Pecham and his Perspectiva communis in their historical context. The text and translation of this work, accompanied by copious scholarly apparatus, should be illuminating to both the historian of medieval science and the general reader in intellectual history who seeks a reliable introduction to medieval optics. MARGARETJ. OSLER Harvey Mudd College Berkeley: Principles of Human Knowledge: Text and Critical Essays. Ed. by C. M. Turbayne. (New York: The Bobbs-Merrill Co., Inc., 1970. Pp. xxv + 338. $3.50) Colin Murray Turbayne has long been among the foremost of Berkeley expositors and editors. His introductions to and editions of Berkeley's works for the Library of Liberal Arts are both scholarly and thought provoking. Although other collections of Berkeley criticisms can be found, e.g., Steinkraus', Armstrong's, and that of the University of California philosophy department, Turbayne's volume has the unique advantage of containing the text of The Principles o/ Human Knowledge under his own editorship together with a number of essays on Berkeleianism both old as well as specially written for this publication. The earlier volume edited by D. M. Armstrong and C. B. Martin, a collection of critical essays on both Locke and Berkeley, was put together on the premise that there were not enough good articles about either philosopher to justify separate studies of them. Turbayne remedies this defect then by the inclusion of new essays--one by himself on Berkeley's metaphysical grammar; one by James W. Cornman on theoretical terms, Berkeleian notions, and minds; and one by Paul J. Olscamp on Berkeley's ethical theory--and by the addition of an introduction which emphasizes the uniqueness and richness of Berkeley's philosophical thought as against the mistaken but dominant view that he was but an "ad interim stage in the reductio ad absurdum argument of British empiricism," a view that sees Berkeley as "an inconsistent Hume who, given Locke's original premise, failed to deduce the whole BOOK REVIEWS 511 of the absurd conclusion, the deepest skepticism" (Introduction, x). To further make his stand apparent he gives us in the introduction an analytic chart (with section references to the Principles) showing by paired items contrasts between "The Traditional Doctrine" and "Berkeley's Rival Theory." It is to Turbayne's credit that he has seen fit to bring together materials pertaining to Berkeley's missing Part II of the Principles (only Part I, the Introduction and the Draft Introduction are extant, Part II was lost in Italy, and Part III was never written as such) and thus has taken seriously Berkeley as a philosopher of mind and as an ethicist. Part II was begun, though lost, as the letter to the philosopher's American follower, Samuel Johnson, shows us. Among previously printed material illustrative of this facet of Berkeley's philosophizing, Turbayne has included in the...