The federal government already has borrowed all the money it’s allowed to borrow under current law, a total of $16.4 trillion. That limit is the so-called “debt ceiling,” and our country reached it on Dec. 31.

Hitting the debt ceiling would be no big deal if our government could live within its means, but just now that seems impossible.

Though Congress has yet to pass a proper budget for the current fiscal year, existing law commits the government to spending about $4 trillion this year, though it expects to receive only about $3 trillion in revenues. Either we need to cut spending by one fourth, immediately, or we need to borrow another $1 trillion, just to get through this year.

Hence the impasse: The president and the Democrats in the Senate don’t want to cut spending — President Barack Obama actually wants more spending — and the Republicans don’t want to let Obama keep mortgaging America’s future to pay for more of whatever he’s bought with the last $5 trillion he’s put on the national tab.

While the president and the Republican leaders in the House are wrangling over whether and how much to raise the debt ceiling, some scholars have argued that the debt ceiling itself is unconstitutional and that the president should simply authorize the Treasury to keep selling bonds beyond the $16.4 trillion limit.

House Minority Leader Nancy Pelosi this week endorsed that approach: “If I were president,” she said on the CBS program “Face the Nation,” “I’d use the Fourteenth Amendment, which says that the debt of the United States will always be paid.”

Pelosi was summarizing the provisions of Section 4 of the Fourteenth Amendment, which was adopted as a part of the post-Civil War Reconstruction. It states: “The validity of the public debt of the United States, authorized by law … shall not be questioned. But neither the United States nor any state shall assume or pay any debt or obligation incurred in aid of insurrection or rebellion against the United States … but all such debts, obligations and claims shall be held illegal and void.”

At first glance, the text seems clear enough. The victorious Union declared “void” and repudiated all the debts incurred by the rebellious states, and to reassure its own creditors, the Union also declared affirmatively that the legitimate obligations of the United States, including specifically those incurred during the suppression of the rebellion, would never be thus repudiated.

In law, however, nothing is simple. One might argue that everything that Congress has proposed to spend money on — including interest payments on our existing debt, paying for goods and services already received, plus paying the salaries of federal employees and supporting ongoing benefits such as Social Security — all count equally as “debts.”

Not to pay those debts on time, which is what will happen in a month or so if the government cannot borrow any more money, might be thought of as questioning the validity of that debt.

There are two fundamental problems with this theory, however, and President Obama has wisely made clear that he does not embrace it.

First, there might not be any buyers for bonds not explicitly “authorized by law” through the formal raising of the debt ceiling. Only such “authorized” debts are guaranteed by the Fourteenth Amendment, and there may be sufficient doubt in investors’ minds that they will not buy unauthorized bonds or that they would demand outrageously high rates of interest for them.

Second, not everything the Congress has committed to spend money on really is a “debt” in the relevant sense. The full context of Section 4 strongly indicates that the relevant “debt” is the money that has been borrowed by the government. Though millions of people count on getting their Social Security checks, anticipated benefits are not legally the recipients’ property. The government has promised to pay certain benefits, and though those promises count as moral obligations, they are not true debts, and the government retains the right to modify them at any time.

If anything, Section 4 suggests a different sort of resolution to the debt ceiling crisis than Pelosi envisions. It directs the president, when cash runs short, to pay the bondholders first and to deal with any revenue shortfall by laying off government workers and to stop paying for Social Security and other benefits.

If that happened, you can be sure that the public outcry would force Congress, the president or both to compromise — and fast.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.