Tim Worstall gets it

There was somewhere between none and fuck all economic growth in the US (and many other economies) in the 1929-1945 period. But the production frontier continued to move outwards, indeed, the 30s are one of the all time great decades for both technology and productivity improvements. The 50s to the 80s were simply playing catch up, in the same way that China and India are now.

And:

For it’s…saying that the great Post WWII economic expansion was nothing to do with high unionisation rates, Bretton Woods, restrictions upon capital movements, high marginal tax rates, fixed exchange rates or any other of the “liberal” or “social democratic” (use one for the US, the second for Europe) theories that are so often advanced.

The full post is here.