Wages and spending

During the Great Depression, the classical theory defined economic collapse as simply a lost incentive to produce. Mass unemployment was caused only by high and rigid real wages. The proper solution was to cut wages.
To Keynes, the determination of wages is more complicated. First, he argued that it is not real but nominal wages that are set in negotiations between employers and workers, as opposed to a barter relationship. First, nominal wage cuts would be difficult to put into effect because of laws and wage contracts. Even classical economists admitted that these exist; unlike Keynes, they advocated abolishing minimum wages, unions, and long-term contracts, increasing labor-market flexibility. However, to Keynes, people will resist nominal wage reductions, even without unions, until they see other wages falling and a general fall of prices. (His prediction that mass unemployment would be necessary to deflate sterling wages back to pre-war gold values had been proven right in the 1920s).
He also argued that to boost employment, real wages had to go down: nominal wages would have to fall more than prices. However, doing so would reduce consumer demand, so that the aggregate demand for goods would drop. This would in turn reduce business sales revenues and expected profits. Investment in new plants and equipment—perhaps already discouraged by previous excesses—would then become more risky, less likely. Instead of raising business expectations, wage cuts could make matters much worse.
Further, if wages and prices were falling, people would start to expect them to fall. This could make the economy spiral downward as those who had money would simply wait as falling prices made it more valuable—rather than spending. As Irving Fisher argued in 1933, in his Debt-Deflation Theory of Great Depressions, deflation (falling prices) can make a depression deeper as falling prices and wages made pre-existing nominal debts more valuable in real terms.