A material object is constituted by a sum of parts all of which are essential to the sum but some of which seem inessential to the object itself. Such object/sum of parts pairs include my body/its torso and appendages and my desk/its top, drawers, and legs. In these instances, we are dealing with objects and their components. But, fundamentally, we may also speak, as Locke does, of an object and its constitutive matter—a “mass of particles”—or even of that aggregate and (...) the sum of subatomic particles ‘making it up’. The “problem of material constitution” (henceforth, PMC) is generated by assuming inter alia that the members of any such pair are numerically identical, that is, that the constituted and the constituting are one and the same thing. (shrink)