Subject: Re: The MacroEconomic Future
"So if Congress authorizes a given level of spending that exceeds current estimated revenues, there's no presumption that the difference has to be - or is intended to be - met by issuing debt. Congress has to choose how the shortfall will be funded."

Having a limit on the debt doesn't change that.
Rather than having a limit, make spending bills specify the source of funding - with debt as a default in the absence of any specific source.

It's really too late to be discussing debt limits when the spending is already authorized.