The most important thing about tightening? How long, how long

At midday on December 16, the Fed will begin a tightening cycle, raising the overnight cost of money — the Fed funds rate — for the first time since 2004. Finance professionals in their thirties have had no firsthand experience with the event.

This will be the ninth such cycle since 1955. The most important thing: how long (oh Lord), how long. Every previous cycle ended in recession, all but one (the 1990s) a straight-line death march. Also in each one, the Fed throughout insisted that it was merely following markets, tightening for our own good to prevent “overheating,” and intended a “soft landing” — a nifty slowdown without recession.

Given the response yesterday to another central bank’s action, we and the Fed and everyone are in for surprises. Mr. Draghi of the Euro…