I do appreciate your point about saying versus doing. However, I'm afraid this argument is applying a presumed or inferred intent of the 14th Amendment rather than the plain meaning of the words it actually contains. It also requires judgement of whether default was avoidable. Right, I think it's a bit weak for a courtroom, and if we are talking about a trial on impeachment, that's important.
If this clause does nothing more than bar the US from repudiating its debts, but does not guarantee against default, what good does that do? Well, it seems like it would avoid ill will and possible war with burnt creditors. They probably won't invade us if payment comes late one month because they know the debt is still valid under our own laws. They also know we can't repay if we're all dead, let alone pay late fees or borrow more tomorrow. On the other hand, if we take their money and then denounce obligation to repay outright, they might indeed declare war.
Between these perhaps is where the US publicly profess the validity of its debt while secretly and deliberately avoiding payment period after period. In that case creditors have the greatest power of correction: they can just stop buying our debt.
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