Abstract We derive the formalism of Quantum Mechanics from the axioms of Event-State Theory (EST). While Paper VI established General Relativity as the deterministic limit of computational optimization, this work addresses the stochastic limit where the computational temperature $\lambda$ is non-negligible. We demonstrate that the "Field of Potential" $\Omega$ functions as a phase space of possible next-frames, governed by a Boltzmann-like selection rule. By identifying matter not as point particles but as topological defects ("twists") in the causal graph, we show that the cost function acquires an oscillatory phase component to satisfy lattice continuity. This creates interference effects in the selection probability, reproducing the Feynman Path Integral and the Schrödinger equation. Thus, Quantum Mechanics is identified not as a fundamental framework, but as the statistical mechanics of causal exploration.