In this project, I critically examine the atomistic assumptions that underlie much of the physics of complex systems—assumptions that often support weak-emergence explanations—and explore the possible role of strong emergence. Since Descartes, the dominant explanatory mode in physics has been reductionist: a system’s behavior is taken to be nothing more than the aggregate behavior of its constituent parts, which are presumed to exist independently and to be distinctly identifiable. In classical physics, this picture works well: a heap of sand can be treated as the sum of its grains, each with independent and well-defined existence, and classical statistical mechanics fits comfortably within this framework.

Quantum mechanics complicates this atomistic view. An operationally rigorous part–whole relation in quantum systems must account for the probing mechanisms through which “parts” are defined and accessed. This point has been demonstrated in the extensive literature on entanglement in identical particles—for example, in Paolo Zanardi et al.’s “Quantum Tensor Product Structures Are Observable-Induced” (Physical Review Letters 92, no. 6, 2004).

This project investigates quantum mereology—the relation between parts and wholes in quantum theory—using an operational approach that minimizes historically inherited metaphysical assumptions whose applicability may be limited.