ABSTRACT
The idea of sustainable development, that is to achieve sustainable outcomes from human activity, has been around for some considerable time. Sustainability can be seen as a rather complex notion that, in detail if not in concept, has become so all encompassing and can include so many factors that it is difficult to articulate, never mind measure. One of the consequences is that it is often easier to prove a negative (i.e. that something is not sustainable) than a positive (i.e. that something is sustainable).
