‘Progress’ or ‘evolution,’ industrial and social, is not mere increase and decrease. It is organic growth, chastened and confined and occasionally reversed by decay of innumerable factors, each of which influences and is influenced by those around it; and every such mutual influence varies with the stages which the respective factors have already reached in their growth. In this vital respect all sciences of life are akin to one another, and are unlike physical sciences. And therefore in the later stages of economics, when we are approaching nearly to the conditions of life, biological analogies are to be preferred to mechanical, other things being equal. (Alfred Marshall 1898: 42-3)
Examine the Thesis: Economic models must not be closed. Rational models are not reflective of nature as a function of change and therefore time. The creative and adaptive enterprises of men cause rational economic models to become outdated in the long run. Rational economic models are suitable for short run analysis but can not make accurate long run predictions.
William Dare 