The meaningful economic evaluation of environmental goods depends both upon economic theory being adequate and a congruence between economic and environmental theories of value. Whilst the evaluation of user, and particularly the recreational and amenity aspects of environmental goods, is proving relatively straightforward, it is argued that there remain a number of theoretical, as well as methodological, problems before valid and reliable measurement of the non-use values of environmental goods can be achieved.
In particular, whilst individual preferences and willingness-to-pay for environmental goods may be for the continued existence of the good in general terms, values have to be associated with individual sites. Second, there is as yet little empirical evidence as to the motivations which underlie any such non-use values although economists have speculated about bequest and existence values. Third, the population which benefits through such non-use values in unknown. A number of survey studies are reported which have attempted to address these questions.