Field’s work forces us to face the inconvenient truth that, generally speaking, emergencies will tend to reduce productivity, at least in the short and medium term, because they involve shifting human and financial resources from their previous uses to other, different ones. The way factors of production are combined at a certain time is not necessarily the “right” way: changes, in technology or consumer preferences, induce many, small adjustments every day. The more radical ones, we know, tend to be painful.
But forcing, for instance, workers who are used to making automobiles to make tanks, or ammunition, diminishes their productivity. To say nothing of the need to rework their plants, workers have to learn how to do new things. The knowledge they used to put into their own work becomes anachronistic in part.
For Field, “the narrative history of US wartime productivity has focused almost entirely on the eventual productivity recoveries that took place, ignoring the negative shocks and losses associated with the altered product mix and the intermittently idled capacity resulting from shortages and hoarding of scarce material, components, and sometimes labor.” As he notes, “In 1948, after demobilization was more or less complete and the output mix reverted to something resembling what had prevailed in 1941, total factor productivity in manufacturing was lower than it had been before Pearl Harbor.”
Nor, of course, can we forget the destructive nature of war: it kills people, renders others unable to work, and destroys physical capital, infrastructure, and factories. America’s greatest advantage between 1940 and 1945 was precisely that it was the country furthest from the theater of the fighting:
Although WWII did leave the economy with assets that benefited postwar production capability, it distorted physical capital accumulation, crowding out investment in sectors of the economy not critical to the military effort. … The country achieved production success, but this was not the consequence of a productivity miracle. Between 1941 and 1948, total factor productivity declined in manufacturing and construction and, in the aggregate, grew more slowly than had been true between 1929 and 1941.