Philosophy & Rhetoric

Philosophy and Rhetoric 34.4 (2001) 292-307

The Rhetoric of the Geometrical Method Spinoza's Double Strategy

Christopher P. Long

A double strategy may be apprehended in the first definitions, axioms and propositions of Spinoza's Ethics: the one is rhetorical, the other, systematic. Insofar as these opening passages constitute a geometrical argument that leads ultimately to the strict monism that lies at the heart of Spinoza's philosophy, they function systematically as grounding principles. However, insofar as they are designed to uncover errors at the heart of the Cartesian system, they function rhetorically as a critique of Descartes's equivocal theory of substance. The geometrical mode of presentation lends an aura of necessity to the systematic strategy and tends to eclipse the rhetorical strategy that functions as a critique of Cartesian dualism. ¹ To this extent, the systematic strategy itself functions rhetorically. On the other hand, to the extent that any seventeenth-century attempt to establish a monistic system would inevitably have had to involve a critique of Cartesian dualism, the rhetorical strategy itself functions systematically. Thus, although two distinct strategies are simultaneously discernible in the opening passages of the Ethics, the two work together, each arguing on a different front, to establish Spinoza's monism. By focusing on the rhetorical side of this double strategy, the underlying nature of Spinoza's critique of Descartes can be clarified and certain gaps in the systematic, geometrical argument for monism can be explained.

Descartes's theory of substance

The rhetorical strategy Spinoza employs at the outset of the Ethics involves a brilliant use of equivocation and ambiguity designed to draw a reader dedicated to Cartesian dualism into the heart of an argument designed to [End Page 292] undermine this dualism itself. The impetus behind this rhetorical critique is surely Spinoza's dissatisfaction with Descartes's theory of substance.

1. Descartes's equivocation

Descartes's theory rests upon a fundamental equivocation: on the one hand, the term "substance" is meant strictly to designate that which is absolutely self-sufficient, namely, God; on the other hand, Descartes allows for a weaker understanding of substance, which pertains to those things (specifically res cogitans and res extensa) that require only the concurrence of God in order to exist (Principles I, 51-52; AT VIIIA24-25). ² Thus, for Descartes, although God is, strictly speaking, the only substance, there remains a sense in which both res cogitans and res extensa may be understood as substances as well.

Ultimately, this equivocal understanding of substance may be traced to a tension internal to Descartes between the Aristotelian notion of substance as underlying subject and the seventeenth-century mutation of that notion, which came to be defined in terms of causal self-sufficiency. ³ Jonathan Bennett traces the source of this mutation back to the view held by Aristotle that the existence of some property depends upon its being instantiated--that is, there can be no courage unless there exists someone courageous. He continues his interesting argument thus:

This suggests that there is a relation of dependence running from properties to the things that have them and not conversely. The dependence would be logical: the thesis must be that "existent but uninstantiated property" is conceptually defective, not merely contrary to physics. Thus, one mark of a genuine thing, or substance, is its not being logically dependent for its existence on anything else. (Bennett 1984, 56)

The development of this line of thinking leads to the conception of substance we find both in Descartes's Principles and in Spinoza's Ethics, namely, that a substance must not causally depend on anything outside of itself for its existence. ⁴ However, with Descartes, what emerges out of this tradition is a hybrid understanding of substance in which the term "substance" is not reserved simply for that which is utterly self-sufficient (God), but extends to those things that depend only upon the concurrence of God for their existence (rescogitans and resextensa). This bifurcated understanding of substance seems to stem from the distinction at work in [End Page 293] Aristotle...