The closure program did not begin from its present premise. Its initial question, formulated in 2009, was which structures treated as given in physical theory are necessary, and which are imported by convention. The search was exploratory rather than premise-driven.
The method was reconstructive. Classical mechanics, field theory, relativistic structures, and quantum structures were examined in sequence, with attention to which ingredients were derived internally and which were supplied externally. Across those reconstructions, the same structural pattern recurred in different forms: external frames, pre-supplied backgrounds, and viewpoints outside the system performed work not recovered from the system itself.
The common issue was closure. In each case, the relevant structure was not fully self-contained unless it could be recovered from within, with no external device doing definitional work. Closure emerged as the common requirement behind several initially separate problems. The single premise of the present formulation was reached late in the development, after the reconstructions had already identified the recurring source of external input.
