Once again . . . we are brought back to a fundamental problem in Malebranche’s theory of ideas. What is the ontological status or nature of ideas? They are neither substances nor modifications of any substance. Yet in the Cartesian schema these are the only alternatives: something is either a substance or a modification of a substance. And Malebranche, however modified his Cartesianism, is at least explicit in accepting this ontological dualism.(Steven Nadler, Malebranche and Ideas, 96.)
Nadler nicely states a problem for Malebranchean scholarship: What, for Malebranche, is the ontological status of ideas? Despite their importance to his theory of vision in God, Malebranche seems to leave no metaphysical place for them. He seems to hold three jointly inconsistent positions—that everything is either a substance or a modification of a substance, that ideas are not sub-stances, and that ideas are not modifications.1 Since he clearly denies both that ideas are substances and that they are modifications, on the face of it the only way out of this apparent inconsistency is for him to reject the principle that everything is either a substance or a modification of a substance. And indeed, according to one common interpretation Malebranche restricts the dualism of substances and modifications to created things, thus excluding ideas.2
I shall argue that Malebranche can and does consistently hold all three [End Page 525] positions. He escapes inconsistency by maintaining that although ideas fit into the category of substance, they are not different substances. Rather than being substances (plural), they are identical with one substance, God.
I am of course not alone in seeing this identification of ideas with the substance of God. Nadler, for example, notes it but thinks that it fails to get Malebranche out of the problem of holding three jointly inconsistent positions.3 Nicholas Jolley not only notes it, but also thinks that it provides Malebranche an escape from inconsistency, if only on a surface level. For Jolley, the real problem is that ideas have features incompatible with their being identified with God: in particular, ideas are abstract entities whereas God is not an abstract entity. Though Malebranche admittedly does identify ideas with the substance of God, then, there is a sense in which he cannot really do this.4
The problem Jolley raises is part of the larger problem of how ideas can be identical with the substance of God. Though I will not discuss Jolley’s problem directly, I hope that my discussion of the relation between ideas and the substance of God will throw light on what Jolley takes to be the real problem with identifying ideas with God. I will content myself with showing that Malebranche does hold all three positions in question and explaining how he develops his identification of ideas with the substance of God. In what follows, then, I shall first establish that Malebranche holds the three positions in question, and in particular that he does not restrict the principle that everything is either a substance or a modification to created things. I shall then show how he identifies ideas with the substance of God. Finally, I shall discuss a contrary passage in which Malebranche explicitly denies that intelligible extension (i.e., the idea of extension) is either a substance or a modification.
Malebranche states the principle that everything is either a substance or a mode (or equivalently, a being or a mode) throughout his writings.5 Though he occasionally uses the principle only as it applies to the created world (see LO 237), he almost always states it as applying to everything, created or uncreated: “everything which is, whether it actually exists or not, and consequently [End Page 526] everything intelligible, reduces to being and mode” (LO 639).6 He treats it as a conceptual matter, and thus a necessary truth, that everything must be one or the other: everything “is necessarily either a substance or a mode of being. For in the end all that is can either be conceived of alone or it cannot; there is no middle in contradictory propositions” (LO 513).
Reflecting on how Malebranche understands the principle makes it clearer why Malebranche could neither...