Paul Krugman is questioning whether the Great Depression was truly a monetary phenomenon. He apparently missed Christina Romer's article "What Ended the Great Depression?" where she shows that monetary developments were key not only to the economic recovery of 1933-1936 but also for the post-1938 recovery. These developments were what I would call unconventional monetary policy: FDR's devaluing gold, gold inflows from abroad, and Treasury choosing not to sterilize them. See here for more discussion of her findings--including a striking figure that shows what would have happened had there not been these monetary developments--and how it raises questions for the World War II-ended-the-Great-Depression story.
Update: See Josh's comments below and Zubin Jelveh's take on the numbers.
Update: See Josh's comments below and Zubin Jelveh's take on the numbers.