The Washington Post misled readers in its discussion of Republican claims that its tax cuts will lead to a large boost to GDP growth. The piece quotes Kent Smetters, an economist at the University of Pennsylvania, as saying the Republican growth projections did not take account of debt. This is wrong.
The real issue is whether the projections take account of how close the U.S. economy is to its potential level of output. If the current level of demand is near the point where the economy is hitting serious supply constraints, then the Republican tax cuts will not have much impact on growth. On the other hand, if there is still considerable excess capacity in the form of unemployed and underemployed workers, then it may be possible to increase growth by increasing demand, such as the tax cuts.
Debt is a meaningless concept in this context. Debt would only matter insofar as the flow of income in the form of interest payments on bonds create a source of demand that pull resources away from other uses. With interest payments near a post-war low as a share of GDP, this should not be a major issue for the foreseeable future.
Also, direct debt is only one way in which the government commits flows of future income. Government-granted patent and copyright monopolies are actually much more important in determining future flows of income than debt. In the case of prescription drugs alone, patent and related protections raise the price of drugs by close to $370 billion a year over the free market price, a bit less than 2.0 percent of GDP. This is considerably larger than the current interest burden of the debt, which is approximately 1.6 percent of GDP, net of money refunded from the Federal Reserve Board to the Treasury.
These monopolies are effectively like privately collected taxes. The government grants them as a way to pay for research and creative work. If anyone were really concerned about the burden created by government debt, they would factor in the cost of these monopolies to the public. The decision not to include the costs from patent and copyright monopolies in assessments of the debt makes for a fundamentally dishonest discussion of the issue.