Thirlwall’s Law is counter-intuitive and comes across as shocking. It says that the growth of a nation’s economy is directly proportional to the rate of exports and inversely related to the income elasticity of imports.

The reason it comes as shocking and difficult to believe is that our planet, with all inhabitants and institutions considered resident cannot export (unless there are non-residents such as aliens), but the world still grows.

Now there are several pitfalls in this argument. First, Thirlwall’s law doesn’t fail because the expression for growth rate is indeterminate. Rate of exports is indeterminate and the income elasticity of imports is indeterminate.

So we have

growth = inderminate/indeterminate

Second, the world does not have a central government. So the world as a whole is not comparable to a closed economy with a government.

There is a way in which the world as a whole is balance-of-payments constrained. The argument is by Nicholas Kaldor. In his 1980 article Foundations And Implications Of Free Trade Theory, written in Unemployment In Western Countries – Proceedings Of A Conference Held By The International Economics Association At Bischenberg, France, Kaldor makes the argument for the world balance-of-payments constraint.

Nicholas Kaldor on free trade

In a recent article on the ‘Causes of Growth and Recession in World Trade’,¹ T. F. Cripps has demonstrated that a country is not ‘balance of payments constrained’ if its full employment imports, M*, are less that its import capacity M̅ (as determined by its earning from exports). Such a country is free to choose the level of domestic demand which it considers optimal for its own circumstances,² whereas the other countries from whom M* > M̅, must, under conditions of free trade, reduce their output and employment below the full employment level, and import only what they can afford to finance. He then shows that the sum of imports of the ‘unconstrained’ countries determine the attainable level of production and employment of the ‘constrained’ countries, and the remedy for this situation requires measures that increase the level of ‘full-employment’ imports or else reduce the export share of the ‘unconstrained countries’. The ‘rules of the game’ which would be capable of securing growth and stability in international trade, and of restoring the production of the ‘constrained’ countries to full employment levels, may require discriminatory measure of import control, of the type envisaged in the famous ‘scarce currency clause’ of the Bretton Woods agreement.

In the absence of such measures all countries may suffer a slower rate of growth and a lower level of output and employment, and not only the group of countries whose economic activity is ‘balance-of-payments constrained’. This is because the ‘surplus’ countries’ own exports will be lower with the shrinkage of world trade, and they may not offset this (or not adequately) by domestic reflationary measures so that their imports will also be lower. Provided that the import regulations introduced relate to import propensities (i.e. to the relation of imports to domestic output) and not to the absolute level of imports as such, the very fact that such measures will raise the trade, production and employment of the ‘constrained’ countries will mean that the volume of exports and domestic income of the ‘unconstrained’ countries will also be greater, despite the downward change in their share of world exports.³

Footnotes:

¹Cambridge Economic Policy Review (March 1978), pp, 37-43.

²Owing to the widespread view according to which a given increase in effective demand is more ‘inflationary’ in its consequences if brought about by budgetary measure than if it is the result of additional investment or exports (irrespective of any limitations of import capacity) the inequality or potential inequality in its payments balance may cause a surplus country to regard a lower level of domestic demand as ‘optimal’ in the first case than in the second case.

³In other words, if countries whose ‘full employment’ balance of payments shows a surplus because M* < α W (where M* is the level of full employment imports, α is the share of a particular country’s exports of in world trade W) after a reduction of α to α̂ (α̂ < α) through the imposition of discriminatory measures, the country will still be better off if α̂ W* > α W where W* is the volume of world trade generated under full employment conditions.

[boldening mine]

What Kaldor is saying that because of balance of payments constraint of economies, the world as a whole has a slower growth because surplus nations do not expand domestic demand to the level needed. He is also saying that import controls raise imports rather than reduce them (this because of higher national income) and the exporters’ exports will also increase (even though their share is reducing.).

So the world as an built-in deflationary bias in the way it works.