‘Anecdotal myths’: Tinbergen's influence on Harrod's growth theory

In the history of economic theory, Harrod's transition from the explanation of business cycles in An Essay on the Trade Cycle (1936) to his well-known growth theory in ‘An essay in dynamic theory’ (1939) has always been surrounded by some degree of speculation. One of the topics in that area of speculation concerns the (degree of) influence exerted by Tinbergen on the development of Harrod's growth theory during the 1936–9 period.
This paper argues that Tinbergen's influence on Harrod's work mainly took place on formal, mathematical, grounds, leaving methodological matters untouched. This matter is of some importance in understanding the success of what was initially considered by others as a ‘dynamic’ extension of the Keynesian research programme and later evolved, through the work of Tinbergen and Solow, into a neoclassical growth theory.