NEW YORK • A week before the US Federal Reserve's most critical policy decision in years, Wall Street opinion makers cannot agree on anything. Not only is there no consensus about whether the Fed will end its seven-year-old policy of zero interest rates, but views on the fallout are also wildly disparate.

There are some, like hedge fund titan Ray Dalio, who say an increase will prove an epic blunder in the face of a vulnerable global economy, prompting policymakers to reverse course and start printing money again. There are others, such as Citigroup economist William Lee, who say the expansion is healthy enough seven years after the financial crisis to withstand higher rates.

This week's increase will be the first of several over the course of the next year, they argue. Mr Guy Haselmann, a Scotiabank strategist, says that in his nearly three decades on the Street he has never seen such confusion. Much of that, he notes, is the result of the "mixed messages coming out of the Fed".

One day, a Fed member is expounding on the benefits to delaying a hike, and the next, another is calling for action now.

But the extreme nature of the discord among traders and analysts underscores a bigger, and more important, point: The stakes are high for Fed policymakers right now.

Get this decision wrong, and it could deal a big blow to the economy and to their credibility.

The Fed is slated to announce its decision on Thursday, at the conclusion of its two-day meeting.

As divided as the market is on that decision, it is the aftermath that stirs the real split. In the global-economy-is-too-weak camp, Mr Dalio has plenty of company: Names like Mr Krishna Memani, chief investment officer of OppenheimerFunds Inc, and Mr Larry Summers, the former Treasury secretary and Harvard University president.

Mr Memani, like Mr Dalio, says the increase will prove so premature that policymakers will find themselves having to resort to another round of quantitative easing to resuscitate growth.

While the United States' expansion has been stable, "that's not looking at the full evidence", Mr Memani said. He pointed to the heavy debt burdens of developing economies like China that could weigh down growth.

On the other side, Citigroup's Lee is joined by people like Mr Haselmann and Mr Peter Tchir of Brean Capital. An increase this week, in their view, is warranted - even necessary. "Seven years at zero doesn't seem to have fixed everything," Mr Tchir said.

He puts an unusual twist on last month's market volatility: It underscored the need for the Fed to start raising rates, rather than holding off longer. Historically, accommodative monetary policy has supported too much risk-taking by investors, he said.

Somewhere between the two camps is a middle ground made up of people like Mr Alex Roever, head of US rates strategy at JPMorgan Chase & Co.

There is a risk that bond traders are underestimating the pace of rate increases, which could complicate the tightening process by jarring the market. Even if that is the case, policymakers may not need to reverse right away, he says.

Mr Roever's team predicts two-year Treasury yields will approach 1.7 per cent in a year, from early Friday's 0.71 per cent .

This rate cycle may be tougher for investors to navigate because of challenges at home and abroad, according to the strategist. "It's more complicated monetary policy now," he said.

BLOOMBERG