Majid Borumand

This article reexamines Mulla Sadra's doctrine of substantial motion (al-harakat al-jawhariyyah) in light of four developments largely absent from contemporary Sadrian scholarship: the early modern critique of substantial forms by Descartes and the proponents of the mechanical philosophy; the pragmatist and anti-essentialist critique of natural kinds elaborated by Rorty and his predecessors; the Quinean holism that denies any clean separation between scientific and metaphysical knowledge; and the structural turn in contemporary philosophy of physics, on which the fundamental constituents of nature are individuated by relational properties rather than by intrinsic essences. After reconstructing Sadra's doctrine in its own architecture—the primacy of existence over essence, the ontological unity of substance and accident, and the arguments from accidental motion, generation and corruption, and the reality of time—the article argues that the substantial form on which the doctrine depends has been progressively retired across four centuries of inquiry. Against the rejoinder that metaphysical claims are insulated from scientific change, the article invokes Quinean web-of-belief holism. It further argues that even if substance survives in some form in contemporary physics, the relational properties identified by ontic structural realism and the invariant parameters (charge, mass, spin) of fundamental particles tell decisively against any literal motion in substance. Special relativity in particular undermines the assumption of intrinsic temporality on which Sadra's argument from time depends. While Sadra's isolation from these developments was historically excusable, the persistence of substantial motion as a putatively living doctrine among contemporary Persian philosophers is not.