PPS. Voluntary limitation of families is only possible if the old do not need to rely on thier families to support them. Since voluntary saving for retirement is not always possible and even then not always effective (in times of capitalist meltdown) it follows that the community (in larger terms, the state) must provide, which in turn necessitates a state graduated pension (come back Barbara Castle) and that, in turn, necessitates significant and progressive taxation (and death duties and capital gains taxes).