So, when the debt ceiling binds, every conventional choice involves some sort of unconstitutionality. It's unconstitutional for the govt not to pay its obligations, it's unconstitutional to defy Congress by increasing the debt to fulfill them. There's a third unconsitutional option: the executive cld enforce a tax to balance the budget, say a wealth tax, until the limit is raised. Sure, it's illegal, but so r the alternatives. A wealth tax is good policy, and gets the political incentives right!