We assume that individual voters differ not only according to age but also
productivity. In the steady state, workers with wages in the intermediate r
ange join the retired persons to form a majority and vote for a positive le
vel of social security. When a shock decreases population growth, entrenche
d interests can constrain majority voting decisions and prevent reforms in
the name of entitlements. We show that from a Rawlsian viewpoint it may be
desirable to rely on these entitlements to protect the low wage earners of
the transition generations. However, when the possibility of fixing a basic
pension is introduced, it constitutes a better instrument than entitlement
s.