Worse, he blunders into economics with this gem.
Of course, it is often easy to see that a particular policy produced a short-term economic effect: Obama’s cash-for-clunkers program caused an increase in car sales.That may be "easy", but it may or may not be correct. Most economists suspected (both before and after C4C) that the largest impact of the program would be intertemporal substitution - buying a car now instead of earlier or later. Wikipedia summarizes scholarly (and otherwise) evidence and opinion on both sides.
Social science, unlike philosophy, deals only rarely in clean cases. Most economic events have large second-order effects to consider. And philosophy, unlike alchemy, has nothing to do with the Philosopher's Stone.