A Real Capital equilibrium approach to policy

This tool proposes a reinterpretation of Doughnut Economics in which planetary boundaries are understood not as external limits but as the equilibrium conditions of real capital—the atmosphere, hydrosphere, biosphere, and lithosphere that constitute the biophysical means of production.
When the rate of change of any real capital stock departs from zero, the economy is no longer sustainable; it is consuming its own foundation.
The paper develops a system-dynamics framework linking built capital (infrastructure and technology) to the depletion and regeneration of real capital, identifying equilibrium maintenance as the operational definition of sustainability.
It explains how policy should act as a feedback mechanism that restores equilibrium whenever imbalance arises, transforming the Doughnut from a moral metaphor into a governable operating system for regenerative economics.
In this view, economic success is measured not by growth of throughput but by the stability and persistence of the real capital base.