Solow (1983) once remarked that members of other academic disciplines regard economics with a certain degree of perplexity. While there are always disagreements at the frontiers of research, they are puzzled by the way schools of thought in macroeconomics describe alternative approaches as 'wrong from the ground up'. Growth theory provides a good example of this point, as there is still no consensus as to why growth rates differ, as evidenced by the antithetical neoclassical and Keynesian approaches.