Causes of the Great Depression
Second, there are the monetarists, who believe that the Great Depression started as an ordinary recession, but that significant policy mistakes by monetary authorities (especially the Federal Reserve) caused a shrinking of the money supply which greatly exacerbated the economic situation, causing a recession to descend into the Great Depression. Related to this explanation are those who point to debt deflation causing those who borrow to owe ever more in real terms.
Stimulus (economics)
Milton Friedman argued that the Great Depression was caused by the fact that the Federal Reserve did not counteract the sudden reduction of money stock and velocity. Ben Bernanke argued, instead, that the problem was lack of credit, not lack of money, and hence, during the financial crisis, the Federal Reserve led by Bernanke provided additional credit, not additional liquidity (money), to stimulate the economy back on trail. Jeff Hummel has analyzed the different implications of these two conflicting explanations. President of the Federal Reserve Bank of Richmond, Jeffrey Lacker, with Renee Haltom, has criticized Bernanke's solution because "it encourages excessive risk-taking and contributes to financial instability."