  The increasing difficulties in financing the welfare state and in particular
public retirement pensions have been one of the outcomes both of the decrease
of fertility and birth rates combined with the increase of life expectancy. The
dynamics of retirement pensions are usually studied in Economics using
overlapping generation models. These models are based on simplifying
assumptions like the use of a representative agent to ease the problem of
tractability. Alternatively, we propose to use agent-based modelling (ABM),
relaxing the need for those assumptions and enabling the use of interacting and
heterogeneous agents assigning special importance to the study of
inter-generational relations. We treat pension dynamics both in economics and
political perspectives. The model we build, following the ODD protocol, will
try to understand the dynamics of choice of public versus private retirement
pensions resulting from the conflicting preferences of different agents but
also from the cooperation between them. The aggregation of these individual
preferences is done by voting. We combine a microsimulation approach following
the evolution of synthetic populations along time, with the ABM approach
studying the interactions between the different agent types. Our objective is
to depict the conditions for the survival of the public pensions system
emerging from the relation between egoistic and altruistic individual and
collective behaviours.
