General Discussion

That doesn't mean it's not unconstitutional. But SCOTUS has typically sided with congress/legislation. However, I couldn't find anything showing the debt ceiling law has ever been challenged, probably because it has always been extended on unanimous consent votes.

The argument is straightforward. The 14th amendment says the government must pay it's debts. The only way to do that is by issuing additional debt. And the country has always been in debt. Since there is no other means to pay our debt, the 1917 law requiring congressional approval to extend the debt ceiling is unconstitutional.

The argument against is that the 1917 law has established a tradition for the process that must be followed the increase the debt ceiling. To not have this in place would erode checks and balances established by the constitution. They would argue that a president could set a debt limit that is high enough that it wouldn't be reached for decades.

The counter to that is without an unconstitutional debt limit ceiling, there would be no ceiling assigned.

I'm not sure what other arguments there are.