both." I hesitate to differ from my esteemed
             colleague, but "both" is often a correct answer, as occasionally is "neither." Is one
             supposed to believe in Say's law that supply creates its own demand, or Keynes's law
             that demand creates the needed supply? In the course of a long academic life, I have
             developed Kindleberger's law of alternatives, based on historical examples. Often
             after extended policy debate, the powers that be end up doing both. In 1931 Keynes
             recommended tariffs, others devaluation or depreciation. Outcome: both. During
             World War II there was a vigorous Allied debate as to how best to push back
             German railheads from the Normandy beaches, whether by bombing marshaling
             yards, as the British called them, or bridges. Answer again: both. Nor did questioning
             a German prisoner of war, General des Transportwesen West, under Marshall von
             Runstedt, make clear which was better. American interrogators got the answer from
             Oberst (colonel) Hoffner they wanted - bridges - and the British theirs - marshaling
             Robert Heilbroner has been a Classicist (Say's law?) and a Keynesian (Keynes's
             law?) and has been mildly infected with Marxism, but has never to my knowledge
             adopted the absolutist position of denying all truth to the polar opposite. In economic
             debates we have capitalism versus socialism; perfect markets with rational and
             informed suppliers and demanders versus market failure; monetarism versus
             Keynesianism; fundamentals (such as geog...