I mean, the only reason that Congress can revoke a promise to the Creek Indians is that they have a stronger military. It's not about justice, it's just about strength.
I expect someday Congress with revoke the promise of a social security check, when the system can no longer stand on its own.
If and when the United States Treasury stops honoring bonds that it sells, then you'll have bigger problems than whether or not you get social security income.
It’s a good question — if anything I’d think that a promise is revocable by definition. If there’s no trust involved it’s not so much a promise as...collateral, or something?