An economic theory, put forth by Herman Daly in response to geophysicist M. K. Hubbert’s predictions of the limits of the fossil fuel supply, which regards the notion of economic growth in a finite world as inherently unsustainable. Instead, we should pursue a steady-state economy, which exists within our ecosystem and is similarly finite, non-growing and materially closed (no matter whether it enters or leaves). A steady-state economy assumes that natural resources are scarce, and that our goal must be to maximize productivity and minimize their use.