Eric Zencey wrote that the free market economy Hayek advocated is designed for an infinite planet, and when it runs into physical limits (as any growing system must), the result is a need for centralized planning to mediate the problematic interface of economy and nature. "Planning is planning, whether it's done to minimize poverty and injustice, as socialists were advocating then, or to preserve the minimum flow of ecosystem services that civilization requires, as we are finding increasingly necessary today."[70]