Model Construction and Empirical Selection in Fundamental Physics

Why do modern fundamental physical theories so persistently rely on fields, Lagrangians, and closely related mathematical structures? Standard narratives often interpret this persistence as evidence for the ontological primacy of fields or similar entities. In this paper, I argue for a different interpretation. Drawing on the practice and history of theoretical physics, I propose a model–experience logic of theory construction: successful theories emerge not by revealing ultimate ontological constituents, but by selecting theoretical structures that possess sufficient freedom to accommodate empirical constraints while maintaining internal consistency and extensibility. Quantum field theory, effective field theory, and string theory are analyzed as case studies in this selective process. I argue that fields, strings, and Lagrangian frameworks should be understood as historically stabilized ways of organizing theoretical degrees of freedom, rather than as privileged descriptions of what the world is “fundamentally made of.” This perspective clarifies long-standing debates about the status of fields and particles, reframes the role of unification programs, and situates fundamental physics within a broader methodology common to the natural sciences, albeit realized there in an especially constrained and abstract form.