From Michelson–Morley to Sagnac in Causal Lorentzian Theory (CLT): Global Time, Reciprocity, and the Failure of the c ± v Interpretatio

The Michelson–Morley and Sagnac experiments are often presented as being in concep-tual tension, leading to claims of ether drift, variable light speeds c ± v, or the necessity of aglobal physical time. We show that this tension arises from conflating coordinate time withphysical (proper) time and from elevating kinematic closure relations into physical propaga-tion laws. Within Causal Lorentzian Theory (CLT), spacetime remains locally Minkowskian,light propagates locally at invariant speed c, and observable time differences arise from con-formal time scaling and causal holonomy rather than from variable light speed. CLT elim-inates global physical time by construction and therefore resolves Dingle-type paradoxes,reciprocity confusions, and the misuse of expressions such as t± = L/(c ∓ v). Michelson–Morley probes local inertial structure, while Sagnac reveals the global failure of simultaneityin non-inertial motion. Both experiments are naturally unified within CLT.