"Despite a conspicuous lack of success, central bankers persist with the same policies," he writes on MarketWatch.

"Central banks have convinced themselves that ZIRP [zero-interest-rate policies] and QE [quantitative easing] policies are temporary, believing they will be able to exit from a policy of low rates when appropriate."

The Fed's federal funds rate target stands at a record low of zero to 0.25 percent, and it is finishing its last round of bond purchases (QE3) this month.

"Existing policy does not address pressing issues and may not be capable of restoring economic health," Das says.

So why won't the Fed stop easing? Because that may hurt the economy, he writes.

"Normalization of interest rates, reducing purchases of government bonds and the reduction of central bank holdings of securities all risk higher rates and reduced available funding for economic expansion."

Meanwhile, ace bond investor Jeffrey Gundlach, CEO of DoubleLine Capital, expects the Fed to raise interest rates in 2015, but not based on fundamentals.

Inflation won't be high enough to justify a rate hike, he told CNBC. The Fed has an inflation target of 2 percent. But the Fed's favored inflation measure, the personal consumption expenditures price index, climbed just 1.4 percent in the 12 months through September.

"The Fed should not be raising interest rates, and yet they don't want to be at zero," Gundlach said. "They're in a conundrum. They might raise rates just to see what happens."

• NYT's Irwin: US Economy May Be in Worse Shape Than Data Indicate
• Money Managers See Fed Struggling to Raise Rates in 2015