Spinoza on Extension

Indeed, it is a common view from Aristotle through to Spinoza that for something to be extended is identical with, essentially involves, or entails its having partem extra partem: part(s) outside of part(s), or parts next to parts, or spatially contiguous parts. For example, Descartes writes to More that “I call extended only what is imaginable as having partes extra partes, each of determinate magnitude and figure” (5 February 1649, AT 270). In Chapter 35 of the Guide for the Perplexed, Maimonides writes: “... as [a corporeal thing] has extension it is also divisible”, and Pasnau writes that “there seems to have been general agreement, throughout our four centuries [1274–1761] over what extension is: it is to have partem extra partem” (54). That Spinoza sides with Descartes and Maimonides, and would have sided with Leibniz against Clarke, in understanding spatial extension to entail the kind of divisibility that imperils God’s perfection, is confirmed in another parallel treatment of duration and extension, found in Part II of the Cogitata Metaphysica. This section deals with, among other things, God’s attributes, among which are numbered eternity and infinity. Although this is an early text, and Spinoza will come to reject aspects of its account of the divine attributes in later work, in conjunction with the “Letter on the Infinite” I think we can take the relevant passages as representative of some of Spinoza’s enduring commitments.