We argue that economics – as the scientific method of analyzing trade-offs – can
be helpful (and may even be indispensable) for assessing the trade-off between
intergenerational and intragenerational justice. Economic analysis can delineate the
“opportunity set” of politics with respect to the two normative objectives of inter- and
intragenerational justice, i.e. it can describe which outcomes are feasible in achieving the
two objectives in a given context, and which are not. It can distinguish efficient from
inefficient uses of instruments of justice. It can identify the “opportunity cost” of attaining
one justice to a higher degree, in terms of less achievement of the other. We find that, under
very general conditions, (1) efficiency in the use of instruments of justice implies that there
is rivalry between the two justices and the opportunity cost of either justice is positive; (2)
negative opportunity costs of achieving one justice exist if there is facilitation between the
two justices, which can only happen if instruments of justice are used inefficiently; (3) in
outcomes of inefficient uses of instruments of justice in the interior of the opportunity set,
the two justices are independent of each other and the opportunity cost of either justice is
zero.