有效生产人口的规模门槛——生产力对制度的终极约束

Whether a civilization can independently maintain a complete, advanced, and self-iterating industrial system depends not only on institutional design, but also on whether it possesses a sufficient number of well-educated and technically trained productive population. Based on the analytical framework of the Community Cohesion Model, which decomposes productivity P into the product of technical level (T) and the actual contribution of effective productive population (E_a × η), this paper systematically argues for the "scale threshold of effective productive population" as a strategic judgment tool. This formula strictly applies to "system states" or "system state alliances" that aim to maintain an independent, complete, and self-upgrading industrial system—small states, as "system nodes" within a larger system, fall outside its scope. The paper distinguishes between the "initiation threshold"—the minimum scale required to launch a revolution—and the "maintenance threshold"—the scale required to sustain and upgrade the system in its later stages, with the gap between them potentially reaching multiples. The insurmountability of the maintenance threshold is validated through the cases of Britain, Germany, and the Soviet Union, all of which fell behind as their respective industrial revolutions deepened. The Soviet case is systematically analyzed as an example of how the efficiency coefficient η slid from near 1 to severe degradation: in its early phase, active synthesis and massive external knowledge input drove rapid industrialization; in its later phase, as external input ceased, the planned economy stifled exploration of dispersed unknown knowledge, revolutionary fervor waned, and the administrative command system failed to sustain producers’ willingness, leading to systemic erosion of η. The paper further argues that cross-sovereign alliances suffer a natural efficiency disadvantage, and establishes the intrinsic link between this mechanism and the proposition that "reversion pressure points toward unification" in the Community Cohesion Model. On the eve of the Fourth Industrial Revolution, the initiation threshold is estimated at approximately 500 million effective productive population, while the maintenance threshold may approach one billion. The Chinese civilization is the only political entity capable of independently crossing this threshold within a single civilizational framework.