WITHIN CARTESIANISM there arose many problems deriving from conflicts between Cartesian principles. Inadequate attempts to solve these problems were crucial reasons for the breakdown of Cartesian metaphysics in the late seventeenth and early eighteenth centuries. The major difficulties derived from the acceptance of a dualism of substances seated in a system which included epistemological and causal likeness principles plus an ontological framework in which the categories of substance and modification were exhaustive. The major solutions involved either denying the likeness principles or altering the ontological framework. The first led to unintelligibility; the second, culminating in Hume, opened the way to non-Cartesian metaphysics.

The first section of this study contains a characterization of late seventeenth-century Cartesian metaphysics. The second is an exposition of Foucher's four major criticisms of this system. In the third section, monistic solutions suggested in Descartes and by Spinoza, Foucher, Leibniz, and Locke are considered; in the fourth, the dualistic solutions of the orthodox Cartesians Rohault, R~ gis, Desgabets, La Forge, Le Grand, and Arnauld; and in the fifth, the occasionalist solution of Malebranche. The sixth section is an analysis of these orthodox and occasionalist solutions, showing how each ultimately fails because of dependence upon the ontology of substance and modification. The seventh section is a consideration of Berkeley and Hume in the Cartesian context. A consideration of their systems as offering solutions to Cartesian problems illuminates in new light both the systems and the problems.