There has been a debate led by vicious attack by Paul Krugman that Bernie Sanders’ plans cannot achieve growth of 5.3%. And there have been replies by others.

Coming from a third-world country and seeing an annual growth rate of about 8% in the 10 years of the rule of the UPA government (mid 2004-mid 2014), —meaning real GDP more than doubling in 10 years — despite a global financial crisis and economic slowdown, it appears comical to me that Paul Krugman claiming such a thing is not possible for the United States.

I am a bit unsympathetic to those who quote historical data to try to sneak in an argument that 5.3% is possible. It sounds too apologetic.

If the U.S. fiscal policy was run with a restrictive bias since a long time, there is obviously a huge deflationary bias imparted by policy. So you cannot use that data to either argue one way or the other. The ones using data to try to show it’s possible are playing into the hands of economists such as Paul Krugman whose writing appears nothing but a support for Hillary Clinton.

For a closed economy, the only constraint to growth is the capacity to produce. The United States’ economy suffers no such constraint. At full employment, growth is constrained by rises in productivity and addition to the working population. But productivity itself is endogenous to production because of learning by doing. In addition, rises in incomes motivate people to work harder.

So imagine an economy in which the government’s fiscal stance is held constant for 10 years – i.e., the government expenditure and the tax rates are held constant. Output might fluctuate and even grow but finally the deflationary bias in fiscal policy will drag growth. But you cannot average out 10 years of economic data of hardly any growth to argue out that the economy cannot grow for the next n years.

But things are not easy. What surprises me is that in none of these discussions from either side, is there any discussion of the U.S. balance of payments. The U.S. does not have exports of just a couple of hundred billions and a GDP of some $16 tn. It has exports of about $2.5 tn and GDP of about $16 tn, meaning the GDP is a few multiple of exports. The United States is a net debtor to the rest of the world. So a rapid rise in growth by any means will come at the expense of terribly deteriorating balance of payments which cannot last long.

Of course the above doesn’t mean that things are as pessimistic. It depends on what is going on in the rest of the world and the United States being the economic center of world activity can convince others to boost their economies and there is no reason to assume that it cannot. if there is rapid growth in other economies, the U.S. balance of payments is not something to worry about.

The importance of balance of payments is seriously missing in all discussions. Use of historical data is so wrong here.

tl;dr summary: supply constraints cannot put a limit of some 5% on U.S. growth. It depends on policy makers’ decisions worldwide.