Former Treasury Secretary Lawrence Summers says that Federal Reserve Chair Jerome Powell should signal the possibility of raising interest rates four times in 2022, in order to restore what he argues is the central bank's lost credibility on fighting inflation. The Fed need not "lock in" to boosting its policy rate four times, but Summers says signaling that would show the public the determination of policy makers to stem inflation, which in October ran at the fastest pace in three decades. Summers speaks with David Westin on Bloomberg Television's "Wall Street Week."