The fair and even allocation of non-renewable resources over time is a market failure issue of concern to ecological economics. This issue is also known as 'intergenerational fairness'. It is argued that the market mechanism fails when it comes to allocating the Earth's finite mineral stock fairly and evenly among present and future generations, as future generations are not, and cannot be, present on today's market. In effect, today's market prices do not, and cannot, reflect the preferences of the yet unborn. This is an instance of a market failure passed unrecognized by most mainstream economists, as the concept of Pareto efficiency is entirely static (timeless). Imposing government restrictions on the general level of activity in the economy may be the only way of bringing about a more fair and even intergenerational allocation of the mineral stock. Hence, Nicholas Georgescu-Roegen and Herman Daly, the two leading theorists in the field, have both called for the imposition of such restrictions: Georgescu-Roegen has proposed a minimal bioeconomic program, and Daly has proposed a comprehensive steady-state economy. However, Georgescu-Roegen, Daly, and other economists in the field agree that on a finite Earth, geologic limits will inevitably strain most fairness in the longer run, regardless of any present government restrictions: "Any" rate of extraction and use of the finite stock of non-renewable mineral resources will diminish the remaining stock left over for future generations to use.