This quote of Abba Lerner from his article “The Burden of the National Debt,” in Lloyd A. Metzler et al.,Income, Employment and Public Policy (New York, 1948), p. 256 is frequently quoted in the Post-Keynesian blogosphere:

One of the most effective ways of clearing up this most serious of all semantic confusions is to point out that private debt differs from national debt in being external. It is owed by one person to others. That is what makes it burdensome. Because it is interpersonal the proper analogy is not to national debt but to international debt…. There is no external creditor. “We owe it to ourselves.”

This is unfortunately inconsistent with his “functional finance”. Abba Lerner clearly says that external debt can be problematic. However he probably never realized that if his advise is followed in running fiscal policy, a nation’s balance of payments will deteriorate and its international debt will increase (because current account balance adds to the net international investment position).

Public debt is not the same the negative of the net international investment position but it’s related as the external debt is directly or indirectly picked up by the public sector.

Sound finance is all junk science but Abba Lerner is not your friend to learn about money, debts, deficits and all that.