# as a model-mediated relation between mathematical structures and aspects of physical reality. Language analysis plays no role.

It would be misleading to begin with a theory of the language of physics. Rather we begin with two examples that indicate both the role of LCP and difficulties involved in analyzing it. The first is from the 'bible' of classical physics, Thomson and Tait's Treatise on Natural Philosophy (1867, Vol. I, p. 337). A complete account of the problem of lifting a mass with a crowbar would involve a simultaneous treatment of every part of the crowbar, fulcrum and mass. This, however, is impossible: "...and from our almost compete ignorance of the nature of matter and molecular forces, it is clear that such a treatment of the problem is impossible". In place of this idealized treatment, based on a mechanics of atoms, they outline a practical approach based on macroscopic representations and successive approximations. In the first approximation the crowbar is represented by a perfectly rigid rod and the fulcrum by an immovable point. The second approximation includes corrections due to the bending of the rod. Here again, the ideal treatment would be based on a theory of molecular forces. Since this too is impossible, one substitutes the assumption that the mass is homogeneous and that the forces consequent on a dilation, compression, or distortion are proportional in magnitude and opposite in direction to the deformations. A third approximation is based on the consideration that compression produces heat, while extension develops cold and that both can change the operative length of the rod. Further approximations could include corrections due to heat conduction, thermoelectric currents, and departures from homogeneity. (Ibid., pp. 337‑339)

Atomic physics had not yet been developed. Yet, T and T’ (J. C. Maxwell’s designation) were clear on the explanatory role atoms should play. Ultimately, the properties and activities of gross matter should be explained through atoms and forces. It is worth noting that after an adequate basis for an exact treatment of molecular forces was established (Schrödinger's equation), the T-T’ phenomenological approach still supplies the only reasonable method for treating such problems. For us, as for T and T’, the operative requirement is that an atomic explanation should be possible in principle. The functional integration of mechanics, thermodynamics, electrodynamics, and speculative atomism depended on an overall view of how everything fit together. This is something shaped by and transmitted through the language of physics. This overall view guides inferences and interpretations by determining which factors are pertinent at which level of approximation. This illustrates the type of reasoning that is the normal practice of experimental physics. One uses appropriate bits of thermodynamics, electrodynamics, solid-state physics, etc. in utilizing and calibrating instruments. These are not treated as theories but, for the most part, as facts about the world. An overall view of the world is a prerequisite to seeing how the parts are interrelated on a functional level.