Abstract We introduce the Superpositional Asymmetry Principle (SAP), an effective theoretical framework linking symmetry-breaking dynamics, entropy production, and the suppression of quantum coherence in open quantum systems. Rather than modifying quantum mechanics or postulating a fundamental collapse mechanism, SAP treats classicalization as an emergent, coarse-grained phenomenon described entirely within standard open-system dynamics. By decomposing the system action into symmetry-preserving and symmetry-breaking contributions, we propose a phenomenological scaling law for decoherence rates governed by the ratio of asymmetric to symmetric action intensities and the local von Neumann entropy. The resulting dynamics are formulated within the Lindblad master-equation formalism. SAP unifies symmetry breaking, decoherence, and entropy into a single effective principle and yields experimentally testable predictions distinct from mass-based objective collapse models.