We have two dotted lines overlapped by a solid line. One dotted line starts at the lower left and ascends to the upper right. This line is "Scheduled Benefits". The other dotted line starts at the upper left (barely) and descends to a flat line at 5.1 (of what, it doesn't matter as yet) as is labeled as "Tax Revenues". Now both "Scheduled Benefits" and "Tax Revenues" are dependent on an arithmetic relation between current law tax and benefit formulas and a particular set of economic and demographic assumptions called 'Intermediate Cost'. And under these formulae and assumptions "Scheduled Benefits" and "Tax Revenues" already crossed. Which is one definition of 'crisis'. And in this figure marked by the vertical line.
On the other hand we have something called the 'Social Security Trust Fund'. And things get complicated. Below the crueller.
Okay lets throw an acorn to the 'reformers'. The point at which 'Scheduled Benefits' and 'Tax Revenues' cross is the moment that net cash flow from Social Security to the General Fund turns negative. And by one definition used by CBO scores as a 'primary deficit'.
On the other had current law doesn't see it that way. Under current law the Social Security Commissioner can and will pay full scheduled benefits as long as a combination of current tax income and existing interest earning Trust Fund assets allow. Which explains why the solid line of 'payable benefits' extends beyond 'tax revenues', the difference being in the draw first on interest on Trust Fund assets and then those assets themselves. By that same token the SSA Commissioner has no legal authority to adjust either benefits or revenue, left unaddressed the result would have to be a sudden reset in benefits immediately on Trust Fund Depletion, under current assumptions around 2034.
But that is where the lens begin to distort the respective visions
'Reformers' look at that discontinuity and conclude 'unsustainable'. Or perhaps 'over-promised'. Instead 'Defenders' look at the discontinuity and conclude 'under-resourced'. And I don't have the time tonight to suss out every argument on both sides and still less the arguments for outcomes in between. Because 'reformers' just start from the position of adjusting 'scheduled' down to 'payable' and 'defenders' on the best way of adjusting revenue up to 'scheduled' with little awareness that they are seeing the discontinuity from two sets of glasses.