I definitely agree that Keynesianism is far superior to 'supply side' economics, in terms of economic efficacy, much less issues related to 'social justice'. A fully self-regulating economy with no unemployment or poverty, much less no taxes or public debt, would be far superior to Keynesianism.
For the future, a DDI would be far more certain than Social Security could ever be. Retirees who receive more than the DDI would provide ($2,600/mo.--at $15/hr.; $600/wk. for employed people, but it could be set higher) would surely be allowed to continue to receive that amount.
It just occurred to me, thanks to you, Mr. Langford, that the current maximum retirement benefit, $3,895/mo., could serve as the proposed amount for a DDI in the U.S. Go ahead and make it $3,900/mo.--so $22.50/hr.; $900/wk.; $46,800/yr. for full-time employees. I've been looking for a data point that could serve as a hook on which to hang a significantly higher DDI. It would take a very long time to raise the minimum pay from $7.25/hr. to that amount without inducing inflation, but there would be no reason to refrain from making that change to retirees' incomes immediately, or at least at a greatly accelerated rate.