Scientific explanation typically operates through models, equations, and conceptual frameworks that describe the behaviour of systems. However, such descriptions presuppose that the systems under investigation remain structurally admissible within their governing constraints. This paper clarifies a structural step that precedes normal scientific interpretation: the recognition that explanatory models act as “optical instruments” through which scientists view systems, while the admissibility conditions that permit those systems to exist remain logically prior to those instruments. The Paton System formalises this relationship by distinguishing between descriptive optics (models, equations, theories) and the structural frame that determines whether continuation remains permissible. Within this framework, admissibility defines the boundary conditions under which scientific description remains valid. If a system exceeds those conditions, continuation is no longer structurally permitted regardless of the accuracy of the equations used to describe it. This clarification situates admissibility as the structural frame underlying scientific explanation while maintaining compatibility with existing scientific laws and theories. Rather than replacing scientific models, the framework makes explicit a constraint that is already implicitly recognised across engineering, physics, and computational science when systems exceed their admissible operating domains.
Andrew John Paton (Sun,) studied this question.