… is from pages 149-150 of Elizabeth S. and Harry G. Johnson’s 1978 volume, The Shadow of Keynes; specifically, it’s from Harry Johnson’s essay “Cambridge in the 1950s.” The “Keynesian assertion” to which Johnson refers (earlier on page 149) is “that investment is subject to no budgetary constraint”):
My own view is that the Keynesian assertion is the one that has to go – because it is inconsistent with the observable facts. It implies that investment has nothing to do with the rate of interest, that entrepreneurs can always find all the money they want for investment, and that everything depends on their high animal spirits.
It was about that time – the 1950s – that I began to appreciate the difference between scientific and ideological motivations for theoretical work. I began to realize that more and more Cambridge people in my judgment were perverting economics in order to defend intellectual and emotional positions taken in the 1930s. In particular, for them Keynesian economics was not a theoretical advance to be built on for scientific progress and improved social policy. It was only a tool for furthering left-wing politics at the level of intellectual debate.