Milton Friedman famously argued that “money matters,” but he had a caveat: Money matters with long and variable lags.  Over at Cato Unbound, Sumner suggests that even Friedman was far too Klingian:

Most economists assume that interest rates or the money supply are good
indicators of the stance of monetary policy. Because of this they
mis-identify monetary shocks, and this leads to estimates of long and
variable lags in the effect on NGDP. But this view is hard to reconcile
with the fact that when shocks are easily identifiable, the lags seem
very short.

Sumner’s key test cases:

The most expansionary monetary shock in U.S. history, by
far, was the 1933 dollar devaluation and the decision to leave the gold
standard. During the first four months of this policy, the WPI rose by
14 percent and industrial production soared 57 percent, regaining half
the ground lost in the previous 3 ½ years. And these stunning gains in
nominal output occurred during one of the worst financial crises in
American history, when much of the banking system was shut down for
months. Other easily-identified monetary shocks, such as the 17 percent
decline in the U.S. monetary base between late 1920 and late 1921 had
an immediate and severe impact on both prices and output.

Do any Klingians care to comment?