Two outstanding critics of standard economics, Kenneth Boulding and Nicholas Georgescu-Roegen, have argued powerfully that the mechanical analogue should be replaced by an evolutionary approach (Boulding 1981: Georgescu-Roegen 1971). In recent years the challenge has evoked a growing response; a significant number of economists are exploring economic biology and there are signs that cliometricians are beginning to question the dominant influence of mechanical models on their work. 1 The patron saint of this movement is Alfred Marshall, whose famous declaration provides a motto: ‘The Mecca of the economist is economic biology rather than economic dynamics’ (Marshall 1898:43). Let us explore Marshall’s case for economic biology and assess the contribution which he made to advance the cause.
By about 1875 Marshall had completed his ideas on the theory of value, but he did not publish his work at that time, partly because he was grappling with the problems raised by time and increasing returns. During this fertile period he stood at the confluence of two great intellectual traditions—the classical or Newtonian (Adam Smith, Ricardo, John Stuart Mill), and the Darwinian (Paley, Malthus, Darwin). The Darwinian tradition can be traced to William Paley who, in the words of Keynes ‘was for a generation or more an intellectual influence on Cambridge only second to Newton. Perhaps in a sense he was the first of the Cambridge economists’ (Keynes 1933:108). In 1785 Malthus, in his first year as an undergraduate in Cambridge, was tutored by William Frend, a pupil of Paley’s, and it is significant that in that year Paley’s