I have gone from the occasional smile to scratching my head now and then to "WTF" moments.

All that said, the economists who designed these interventions had their reasons. They thought lower interest rates and liquidity injections would create jobs, spur investment, and eventually produce inflation.

Then the idea was to reduce the stimulus before inflation got out of control. The problem is that none of these wishes came true.

The Philips Curve That Doesn't Work Anymore

The key gauge of central bankers for assessing this tricky process is the unemployment rate.

An economy at "full employment" is one in which inflation is right around the corner. The theoretical relationship looks something like this – chart from Gary Shilling.

In fact, we now have very low unemployment, accompanied by stubbornly low inflation.

Why is that? No one really knows.

All sorts of theories are floating around, but none have yet proven helpful in restoring the Phillips Curve.