It's true that it's not strictly necessary that the "backing taxation" for this scheme be specifically on income, but due to historical circumstance this the la

It's true that it's not strictly necessary that the "backing taxation" for this scheme be specifically on income, but due to historical circumstance this the largest pillar currently supporting the US system. Theoretically income should be related to productivity so it is a reasonable backing to balance against inflation. The onus is on those who'd like to replace the system to justify a better alternative.