This post is the second of a series I am writing on the second edition of my Free Market Economics that has been published in association with the Institute of Economic Affairs in London. This post focuses on the single most important principle in economics which now goes under the name Say’s Law. But it is a principle that was deliberately eliminated from within mainstream economic theory by Keynes in his General Theory and has disappeared from virtually all economic discourse since that time.

The book was itself written because there is literally no economics text of any kind anywhere that discusses Say’s Law. Yet it was this principle that made it perfectly obvious that the stimulus being applied across the world from the end of 2008 would lead to an economic stagnation that would last years on end. That is why I immediately began to write the book then and there, but it is also why I had published in February 2009, just as the stimulus was getting under way, an article with the title, “The Dangerous Return to Keynesian Economics”. The article specifically discussed the crucial disappearance of Say’s Law and included this forecast:

“Just as the causes of this downturn cannot be charted through a Keynesian demand-deficiency model, neither can the solution. The world’s economies are not suffering from a lack of demand, and the right policy response is not a demand stimulus. Increased public sector spending will only add to the market confusions that already exist.

“What is potentially catastrophic would be to try to spend our way to recovery. The recession that will follow will be deep, prolonged and potentially take years to overcome.”

While virtually the whole of the economics profession remains flummoxed by what has happened since the stimulus, neither my students nor myself have been in any doubt. It has been as obvious as the noonday sun, but invisible to anyone brought up on modern macroeconomics which has embedded the theory of aggregate demand, Keynes’s disastrous contribution to economic theory.

Say’s Law specifically stated that demand deficiency, that is, a deficiency of aggregate demand, could never be the cause of a recession (or in the archaic language of the classics, “there is no such thing as a general glut”). It then specifically told governments that while some additional public expenditure during recessions might do some small good, such a stimulus would never restore an economy to robust health but would, instead, do serious damage, and the larger the stimulus the more damage it would do.

The book explains the nature of Keynesian economics but also explains why a stimulus could not possibly have returned our economies to rapid rates of growth and low unemployment. The experience of the past six years ought to have made all this supremely evident in practice. But without an understanding of Say’s Law, there is not a chance in the world anyone will understand why the stimulus has been the colossal failure it has been.

Although named Say’s Law after the early nineteenth century French economist J.-B. Say, it was a principle that was part of the bedrock foundation of economic theory right up until 1936. But what will never be told to you by any Keynesian economist (in large part because they don’t even know themselves) is that the term Say’s Law was invented in the twentieth century by an American economist who thought it was absolutely essential for clear thinking in economics and brought into active use only in the 1920s.

If for no other reason, I commend my book to you because it is the only place where one can have Say’s Law explained in a way that makes you understand what economic theory has lost. It will also explain why the stimulus did not work and what must be done instead, reasons enough to buy the book I would hope. But there are also others which I will come back to in later posts.