Majid Borumand

This article argues that Mulla Sadra's doctrine of substantial motion (al-harakat al-jawhariyyah) cannot survive contact with post-Cartesian inquiry. The doctrine depends on the Aristotelian substantial form, and that form has been progressively retired by four convergent developments: the mechanical philosophy's dismantling of substantial forms, the pragmatist anti-essentialism running from James through Rorty, Quinean holism denying any clean separation of science from metaphysics, and the structural turn in physics, on which fundamental constituents are individuated by relations, not intrinsic essences. With the form retired, the flagship argument from accidental to substantial motion loses its subject. The standard defensive move—recasting the doctrine as a thesis about the act of existence—is then shown to fail on either reading. Read thinly, it is a truism that has existed in various guises since Heraclitus, one that physics replaces rather than confirms. Read richly, its teleological, ascending character contradicts the findings of physics, while the bare gradation of existence (tashkik al-wujud) it invokes under-determines the observed diversity of the universe's furniture. Sadra's argument from the reality of time is disqualified directly: special relativity denies the intrinsic, frame-independent temporality it requires. Sadra's historical isolation was excusable; the doctrine's persistence among contemporary philosophers is not.