When our empirical tests fail to yield expected results we do not take our theory back to the drawing board, but we fudge some explanation that we think might be plausible. These are not trivial matters. They lead economists to incorrect interpretations of economic motivations, transactions and processes, and, as a result, to policy recommendations that can be guaranteed to fail.
I offer two examples. The exchange rate is not a price of anything Economists cannot understand how the exchange rate of small resource poor countries like Barbados, Cayman, the Bahamas and the OECS can remain unchanged in terms of their numeraire (the US dollar) indefinitely, because they deceive themselves into thinking that the exchange rate is a price.