Cause and effect are difficult to figure out, though we have the benefit of lots of hindsight. When you get into a problem so crazy and horrible, you sometimes have to experiment a bit to figure out how to fix things (aka "doing something"), and some of these experiments will invariably go backwards. Hoover's problem was probably he underestimated and misidentified the causes of the crash. Roosevelt experimented a lot also, and had just as many failures as successes, but he was like General Grant during the Civil War who wasn't afraid to loose troops in order to win.