Academics place much more importance on rigorous logic. There is also admiration in the profession for subtle reasoning. And mastery of the craft shows itself in the elegance of the intellectual super-structure…. The practitioner, on the other hand, uses economic theory only to the extent that he finds it useful in comprehending the problem at hand, so that practical courses of action will emerge which can be evaluated not merely in narrow economic cost-benefit terms, but by taking into account a wider range of considerations…. A practitioner is not judged by the rigour of his logic or by the elegance of his presentation. He is judged by results.