Towards a Unified Theory of Dynamic Cybernetic Stability: Con- structibility Erosion as the Common Downstream of Variety, In- formation, and Relevance Failure

Four prior papers establish necessary conditions for adaptive system function: requisite variety Paper 1, effective information flow under channel degradation Paper 2, temporal relevance of feedback Paper 3, and reachable future state space Paper 4. Paper 1 further proves that variety matching is insufficient — an irreducible epistemic deficit 𝜀𝑡 > 0 drives a stress process 𝑆𝑡 whose long-run behavior is governed by the threshold 𝜇𝜑 ≶ 𝜆𝑆crit (Stress-Bounded Control Theorem), independently of controller variety. This paper provides the unifying layer. We show that the failure modes across all four papers — variety erosion, epistemic stress accumulation, effective information collapse, source-intrinsic decorrelation, and constructibility erosion — are not independent phenomena but analytically separable drivers of a single downstream quantity, the Constructibility Erosion Rate CER(𝑡) = −𝑑𝒞/𝑑𝑡. We formalize Dynamic Cybernetic Stability (DCS) as a two-tier joint condition: a stress feasibility gate (Paper 1’s threshold 𝜇𝜑 0 — and show, via Paper 1’s Proposition 4.1, that CER(𝑡) > 0 can arise with all upstream conditions nominally satisfied. We propose a unified monitoring architecture, five cross-paper empirical predictions (including the predicted lead-time extension from Paper 1’s accumulation alarm), and five open problems whose resolution would convert the synthesis into a quantitative theory.