This paper presents a concise, analytic derivation of the two standard postulates of special relativity—the principle of relativity (invariance of the laws of physics in all inertial frames) and the constancy of the speed of light (a finite, invariant maximum causal speed)—from a single primitive definition of asymmetric necessary conditions between events. Without assuming spacetime symmetries, electromagnetism, or specific experiments, the argument shows that directed dependency chains (arising from asymmetry in necessary conditions) force temporal order, finite propagation speeds, strict locality, and ultimately the postulates. This provides an alternative foundational perspective that emphasizes the near-tautological nature of special relativity once necessary conditions are defined asymmetrically. Historical experiments (e.g., Michelson–Morley) confirm adherence to the derived structure but are not foundational to the argument.