ABSTRACT
The concept of natural law in physics is quite distinct from the concept of a constraint. A natural law is inexorable and incorporeal, whereas a constraint can be accidental or arbitrary and must have some distinct physical embodiment in the form of a structure. Even the most abstract symbols must have a physical embodiment, however arbitrary the symbol vehicle structure may be. The reason that constraints are not redundant or inconsistent with respect to the laws of motion is that they are alternative descriptions of the system. Some constraints could in principle be looked at in terms of their detailed dynamics and would be found to obey the laws of motion. Physicists often regard the dissipative measurement process as more fundamental than the unobservable, formal determinism of the dynamical laws. Measuring devices are non-integrable constraints which classify and record alternatives, and are not subject to detailed description in terms of the underlying dynamics, even in principle.
