I have been asked by an economist friend, who is quite well versed in macro, whether it is worth reading The General Theory and if not, what should be read instead to get a sense of what Keynes wrote. This was my answer:
My view is that there is no reason that I can think of to read The General Theory cold without some specific purpose and question in mind.
Today, it’s a book for scholars alone, even more so than in 1936 when it was published. But then, all the presuppositions of classical theory were alive so that many of the issues and statements made were clear enough to everyone so that they knew what he was on about. A great deal of time of mine has been understanding the presuppositions of classical theory – the beliefs that were so entrenched that no one even bothered to state them – so that I can read what Keynes was saying against the background of a classical understanding of how things worked. Since that is basically what I do believe is true, I can read Keynes almost the same way as Frank Knight, say, and can see things as they might have.
But what has given me an entirely different perspective is that I came to Keynes not just with the presuppositions of the 1930s in my mind, but also with the presuppositions of the 1840s. It’s with the conceptual approach of John Stuart Mill that I read the GT, and from that perspective, the book is so backwards, so incoherent and so illogical, that it defies belief to me every time I open it. But the presuppositions of almost all economists today are founded on the Keynes-Hicks-Hanson-Samuelson axis which make Keynes seem sensible and Mill incomprehensible. For me, as for Mill, it is so unmistakably true that demand is constituted by value adding supply that I am amazed that no one else can see it or why it matters. And even though a Keynesian stimulus has failed on each and every occasion it has been applied, the belief in aggregate demand independent of aggregate supply remains so entrenched that it is literally impossible for an economist to understand why the latest attempts at a stimulus did not work, and must come to the conclusion that things would have been even worse had the stimulus not been applied. It is not that they are dishonest or lack the most intensive economics education we can provide today. It is that their professional deformation, that began with their first principles course, has never gone away.
What to read instead? All I can say is that I wrote my Free Market Economics at the start of the post-GFC stimulus because there was then no other economics text anywhere to explain why a stimulus would make things worse. The best I can therefore suggest is the second edition which is the economics of Mill brought up to date as best I could do it.