The causes of the Great Depression are hotly disputed by scholars even to this day. No one knows the ultimate reason why the economy started plunging downhill in 1929. However, several things are certain:

• There was a variety of things wrong with the economy going into 1929, and they had been deteriorating throughout the decade.

• The conservative economic policies of the 1920s -- low taxes, little regulation, lack of anti-trust enforcement -- did nothing to stop the August recession and the October stock market crash.

• Hoover kept the Federal Reserve from expanding the money supply while bank panics and billions in lost deposits were contracting it. The Fed's inaction was the reason why the initial recession turned into a prolonged depression.

• The economy continually sank throughout Hoover's entire term. Under Roosevelt's New Deal, it rose five out of seven years.

• Attempts to blame Big Government for the Depression do not withstand serious scrutiny. The Smoot-Hawley Tariff had a minor impact because trade formed only 6 percent of the U.S. economy, and reducing trade gave Americans only that much more money to spend domestically. Hoover's other attempts at government intervention came mostly during his last year in office, when the Depression was already at its depth.

• The first nations to come out of the Great Depression -- Sweden, Germany, Great Britain, and then everyone else -- did so after they adopted the Keynesian solution of heavy deficit government spending.

• Keynesian economic policies have eliminated the depression from the world's economies in the six decades that have followed.