The Traite des systemes is a milestone in the intellectual history of
the eighteenth century. This is a study of its content, structure,
sources and importance. It includes a discussion of Condillac's analysis
of good and bad systems, the adequacy of his knowledge and under-
standing of the speculative metaphysics of the preceding century, the
effectiveness of his method of attack on seventeenth-century
metaphysical systems, his conception of empirical and scientific method,
and in particular his understanding of the role of hypotheses, his
application of the Newtonian scientific method to politics, physics, and
the arts, and, finally, his preoccupation with the meaning of words and
with the origin and purpose oflanguage. Speculative metaphysical
systems, such as those of Descartes, Malebranche, Boursier, Leibniz and
Spinoza, are attacked by Con- dillac, as are popular superstitions and
prejudices, with the weapon of linguistic criticism. It is the
systematic use of this weapon which makes the Traite des systemes more
than a reflection of his contem- poraries' antipathy towards speculative
metaphysics. In memory of my MOTHER and FATHER ACKNOWLEDGMENTS I wish to
acknowledge my indebtedness to several people. I should like first and
foremost to thank Dr. W. H. Barber, who has for many years tirelessly
given me encouragement and invaluable assistance. I wish to thank also
Professors RH. Rasmussen, A. D. Wilshere and C. Wake for their help and
their support in the early days of the preparation of this study. lowe
special thanks also to Mrs. M. V.