A focused page for the dark matter, dark energy, and backreaction argument.
Dark matter and dark energy are usually treated as independent discoveries. The diagnostic alternative asks whether both may be coupled symptoms of a single overextended modelling framework.
Diagnostic thesis: the inference from discrepancy to hidden content is not automatically licensed. It requires a stable bridge between the formal model, the relevant regime, and the physical target.
This does not deny the empirical success of ΛCDM. It separates success within a licensed regime from unrestricted applicability across regimes where the assumptions themselves are under diagnostic pressure.