Keynesianism could probably have prevented World War II

Let us look at the simple facts relating to the rise of the Nazi party in the 1930s.

This is the Nazi party share of the vote in federal elections in the Weimar Republic from 1924 to 1933:

Date | % of Vote | Reichstag Seats
May 1924 | 6.5% | 32
Dec. 1924 | 3.0% | 14
May 1928 | 2.6% | 12
Sep. 1930 | 18.3% | 107
July 1932 | 37.3% | 230
Nov. 1932 | 33.1% | 196
March 1933 | 43.9% | 288
http://en.wikipedia.org/wiki/Nazi_Party#Federal_election_results

By 1928, during the economic boom in Germany, the Nazi party vote looked like it was almost dead and was only 2.6%. Remarkably, even in the aftermath of the Weimar hyperinflation in 1924 it was only 3%.

When the deflationary depression struck Germany from 1929–1932, it soared to 18.3% (September 1930), then 37.3% (July 1932), and finally to 43.9% in March 1933 in the aftermath of the Great Depression. Hitler became Chancellor on 30 January, 1933, admittedly after some political jockeying.

It was the depression that essentially made the Nazi party and made Hitler chancellor.

Had the Weimar Republic government intervened in 1930 and 1931 onwards with policies to stabilise the financial system, provide massive fiscal stimulus, and employment programs, then the Great Depression in Germany would have been quickly reversed and prevented and the Nazi share of the vote would very probably have stayed relatively low. Hitler would never have been a plausible candidate for chancellor in 1933 and crucially the threat from communism would also have been much weaker.

Without the Nazis, it seems very difficult to see how the Second World War would have happened.