I quote the following passage from William Manchester's The Glory and the Dream because it summarizes the liberal, New Deal position on the cause of the Great Depression and recessions in general:
"The real blame lay in he false underpinnings of the Coolidge-Hoover prosperity. Seen in perspective, the Depression appears to have been the last convulsion of the industrial revolution, creating a hiatus [break] before the technological revolution. In the aftermath of the World War [One], the techniques of mass production combine to increase the efficiency per man-hour by over 40 percent. This enormous output of goods clearly required a corresponding increase of consumer buying power—that is, higher wages. But the worker's income in the 1920s didn't rise with his productivity."
But some of the increased efficiency became consumer buying power through the issuing of credit. Hence people bought on credit during the 20s, and when credit-based buying collapsed in 1929-1930, the entire economy went into a downward spiral. Less demand resulted in less production, and so in workers being fired, and so in a further decrease in demand. It was Herbert Hoover himself who used the term "Depression," trying to imply the whole affair was about a wrong mindset, a lack of confidence. If only confidence would return, the economic downturn would reverse itself.
The natural conclusion, if you buy the analysis is the quoted paragraph, is that all society needed to do was to give people more buying power. Society needed to "share the wealth" as socialists said. Then better-paid workers would buy more things; manufacturers would hire more people to make more things, then these hired people would also spend more, until "happy days are here again" [the Democratic Party theme of 1932] and there's "an automobile in every garage" [the Republican slogan on 1928].
But the problems of the Great Depression must have been more fundamental. Under the New Deal [often passed by an alliance of progressive Democrats and progressive Republicans; both parties had conservative wings that resisted the legislation] the federal government used a variety of methods to increase aggregate purchasing power. By 1934 deficit spending was the order of the day. The economy did improve off its 1932-33 lows, but not to anything resembling prosperity. Beginning roughly in 1939 with war orders from Europe, and accelerating in 1940 when U.S. deficits became even larger to prepare for war, the economy finally got back to where it had been in the mid-20s.
Even Democrats worried about the national debt after World War II; by American standards it was unprecedented. But with the slow-motion collapse of the British Empire, the U.S. had become the dominant world power. The revived economy, and high income-tax rates, generated an equally unprecedented stream of revenue to the federal government. Most federal programs were cut back only minimally, and new programs like the Interstate Highway System created jobs and demand for commodities.
When President Franklin Delano Roosevelt and Congress started running up deficits and the national debt in the 1930s they were starting off a small base, most of it left over from military expenditures for World War I. By the late 1950s even most Republican politicians and businessmen believed in deficit spending. Workers and capitalists alike were prospering, if some more than others. It seemed like capitalism propped up by heavy federal spending was the recipe for permanent prosperity.
This all turned sour in the 1970s, following the prosperity of the 1960s resulting from economic imperialism, spending on the Vietnam War and cold war, and the expansion of the New Deal into the Great Society "War on Poverty" programs.
Demand, in itself, could lead to the opposite problem from the Depression: inflation. In order to stop inflation, the Federal Reserve raised interest rates (and tightened the money supply). A series of recessions, interleaved with booms, followed, with aftermath of the most recent and most serious of the recessions still lingering with us.
Also lingering with us is a $17 trillion federal debt. And therein lies the real problem for America and the world. If during periods of prosperity the debt had been paid down (as happened until about 1930), then the only federal debt today would be from the latest recession. Call it $3 to $5 trillion. But no, instead every problem since 1933 has been solved with debt. If you are ideological you can consider it military debt or welfare debt, but it is an obligation of the citizens, regardless of the specifics of its origin.
So where we are now, in early 2014, can be summed up as:
1. The economy has been growing slowly since 2009, partly because of high deficit spending by the government and partly because of the natural tendency to grow off a bottom.
2. Unemployment is well over 6%, and even that excludes a lot of individuals who are under-employed.
It's not Depression or even Great Recession levels, but it isn't prosperity either.
3. Inflation has been minimal, lately.
4. People would buy more products if they made more money. Most employees are highly productive because of technological advances.
5. Because there are plenty of unemployed people, wages are stagnant; employers don't have to bid up wages to retain employees.
6. Economic imperialism is not really working anymore. It costs more to patrol the American empire (the entire world, for practical purposes) than the U.S. gets in economic benefit from the rest of the world (as seen by our negative balance of trade).
7. There is a $17 trillion and growing federal deficit. Interest payments already make up a considerable part of the federal budget, and if interest rates (on average on government debt) climb to say 5%, they will eat up a huge part of the annual federal budget.
In a Goldilocks scenario the capitalist class, either out of self-interest or forced by the federal government, would both increase wages significantly for workers and pay off a substantial part of the federal debt. The wage increase would increase demand, resulting in profits that would compensate the capitalists for their sacrifices. With increased demand more of the federal debt could be paid off; prosperous workers could help some with that. Inevitably another recession would roll around, at which time deficit spending would be appropriate to counter the economic cycle until growth resumed.
Do not plan on the Goldilocks scenario. It won't happen in our broken political system. Republicans have done a good job emphasizing the debt issue, but are unwilling to raise wages or tax the super-rich to reduce the debt. Democrats would raise the minimum wage, but won't tax the capitalists and won't do anything about the debt.
The Federal Reserve will keep making excuses to keep interest rates low, saying it is to help revive the economy. But the real reason is allowing interest rates to rise will show how naked the economy really is. The math is simple. 5% of $17 trillion is $0.85 trillion per year. The fiscal year 2013 federal budget resulted in spending $3.45 trillion. But revenue was just $2.77 trillion. So if interest rates rise to 5% on average, and revenue stays flat, interest payments on the federal debt will eat up over 30% of revenue.
So less spending, even on the military. And less spending means less demand, meaning fewer jobs. And lower tax revenue.
Or Congress can kick the can down the road a few last inches, into the wall of reality, and continue to increase the debt even when the economy is relatively good.
Which just happened when the Democrats and Republicans in Congress raised the debt ceiling.