> More construction in an over-supplied housing market?
You do realize that Keynes' departure from 'classical' economics was a model that depended more on aggregate demand than supply, right?
Classical economics (ie. pre-Keynesian economics) would say "just build more". Keynesian economics states that you should stimulate demand (lower interest rates, increase government spending, increase money supply, etc...). Which is exactly what got us out of the recession.
> It blows my mind that Keynesians can't identify busts that were caused by bubbles.
It's not about whether they can or can't. Some obviously did see the bubble coming (some Goldman Sachs traders famously bet against the housing market). The problem is that too many people profit from the 'bubble', and momentum takes people over the edge (because, like it or not, consumers are NOT rational).