Keynesian economics cannot be used to justify government borrowing to stimulate consumption. This poster describes Neo-Keynesian economics..
Likewise the Austrian School tends not to model the irrational aspect of human market participation - assuming rational actors only.
In real life you will have largely irrational emotionally driven bubbles - be then in tulips, stocks, real estate or iPhone 6/iWatch production.
Over time of course those emotionally driven bubbles die- so the Austrians are right in a macro sense, but you aren't going to predict daily behavior using their theories. Rational Behavior eventually returns to the markets, but there are periods of just plain stupid.
Political Calculations used to do charts showing the periods of order and disorder.. with disorder being largely the results of irrational behavior.
Of course when you have Central banks deliberately creating chaos, disorder is to be expected....because the only rational act is to not play in the market.