Republicans and Democrats spent last summer battling how best to save $2.1 trillion over the next decade. They are spending this summer battling how best to not save $2.1 trillion over the next decade.

In the course of that year, the U.S. government’s fiscal gap — the true measure of the nation’s indebtedness — rose by $11 trillion.

The fiscal gap is the present value difference between projected future spending and revenue. It captures all government liabilities, whether they are official obligations to service Treasury bonds or unofficial commitments, such as paying for food stamps or buying drones.

Some question whether “official” and “unofficial” spending commitments can be added together. But calling particular obligations “official” doesn’t make them economically more important. Indeed, the government would sooner renege on Chinese holding U.S. Treasuries than on Americans collecting Social Security, especially because the U.S. can print money and service its bonds with watered-down dollars.

For its part, economic theory sees through labels and views a country’s official debt for what it is — a linguistic construct devoid of real economic content. In contrast, the fiscal gap is theoretically well-defined and invariant to the choice of labels. Each labeling choice changes the mix of obligations between official and unofficial, but leaves the total unchanged.

Read More at Bloomberg. By Laurence Kotlikoff and Scott Burns.