 A quite different critical approach to discounting is connected with the idea of sustainability. If sustainability is interpreted as meaning that future generations should have access to the same resources as those that the present generation has at its disposal, then sustainability is sure to be in conflict with economic policies based on exponential discounting. However, there are also views on sustainability that allow us to use up natural resources if we replace them by non-natural resources such as new technologies that will compensate for the loss. Such a “weak” notion of sustainability appears to be compatible with policies based on discounting of future effects, but it has been criticized for putting future generations at disadvantage. (Ng 2005)