The argument most tellingly employed by Mums on these occasions, comes in two parts- first, a reminder that Fathers too were once babies; and, second, that the onset of Senility's second childhood might leave a Daddy as vulnerable as a baby, though a good deal less cute and cuddly and, anyway, you can't go through life simply borrowing money off my brothers, you'll need sons and daughters to sponge off in your old age.
More generally, the knowledge that someone we care for, like ourselves, or might care for, like our future selves, could end up poor and vulnerable is sufficient to ensure widespread Democratic support for a Social Insurance scheme which provides an incentive compatible safety net.
What can't arise from Democratic Social Choice is
1) the Rawlsian Liberty principle- this is because differences exist in the capacity to exercise Liberties- whether autonomously or via an attorney or other agent- in a self-regarding way. Those we might most feel a duty of care towards are likely to have the least capacity in this regard. Furthermore, Agent-Principal hazard is most extreme with respect to the most vulnerable, and there is no Secular workaround for this compatible with equal basic liberties for all.
2) the Rawlsian Difference principle- if we don't know if we're going to be losers or winners in the Game of Life, we might want to mitigate catastrophic consequences for losers, not because we think we will be losers- fuck it, if I'm gonna be a loser all my born days just put a bullet in my head, why don't you?- but because we know there's a chance we are going to be winners and so we want to be able to increase the pleasures of victory by pretending to have provided for the losers before hand- just to rub salt in the wound, don'tchaknow? I mean, when I'm crowned Miss Teen Tamil Nadu- as will inevitably happen this year due to astrological alignment- I want to be able to clutch my tiara to my bald spot while jiggling my man-boobs tearfully and say in good conscience that I will henceforth dedicate my life to working for World peas rather than scratching the eyes out of my fellow competitors who advised me to wax before wearing bikini as if my hairy thunder thighs weren't the ultimate turn-on for the old lechers who organize pageants of this sort.
Thus, Rawls has no relevance for Liberal Democracies. What about Illiberal Theocracies?
Take the doctrine of Vilayet-e-Faqih (rule of the Islamic Jurist)- there are two possibilities
1) either it is confined to the care and protection of those with diminished capacity
2) it turns into the rule of Ayatollahs
Iff (2) then there is no Judicial redress for Agent-Principal hazard w.r.t to (1). This is against Fiqh. However, on Rawlsian assumptions, the Guardian of the Poor is dictatorial. But who should be that Guardian?
Behind the veil of ignorance- which is the barzakh of 'harmonious construction' hermeneutics- we can stipulate that the best Guardian is one who, on behalf of the Poor, negotiates the optimal euvoluntary (i.e. uncoerced and mutually beneficial) series of exchanges with the non-Poor.
Thus the 'true' (haqiqi) Vilayet-e-Faqih is consecrated by a process both Rawlsian and Euvoluntary.