Within Wall Street's biggest banks, there are bound to be differences of opinion on what the Federal Reserve will decide to do on Thursday. In fact, Wall Street, in the conceptual sense, remains deeply divided as to whether the U.S. central bank will opt to hike this week.

At Bank of America Merrill Lynch, the house view is that the Fed will increase interest rates, raising its target range by 25 basis points. But David Woo, the bank's head of global rates and currency research, thinks that a September hike would be a mistake.

On Bloomberg Surveillance, Tom Keene asked Woo about his "respectful disagreement" with his colleagues.

"If you just look at the U.S. economic fundamentals — U.S. data — yes, the Fed should be hiking rates," Woo acknowledged.

But whether she likes it or not, Janet Yellen runs the world's central bank. Woo thinks that this should be at the forefront of monetary policymakers' minds when they begin their two-day meeting on Wednesday. He stressed that monetary policymakers needed to keep a more international perspective.

This means taking into account still-soft growth across advanced economies, select emerging markets that are under stress from the collapse in commodity prices, and the deterioration in China's growth outlook.

"The U.S. today is only 15 percent of global GDP," said Woo. "That means the rest of world is more important to the U.S. and the U.S. is important to the rest of the world, so I think from that point of view, I think that's a reality the Fed cannot ignore."

The strategist also echoed sentiments espoused by Deutsche Bank chief U.S. economist Joe LaVorgna, who recently moved his timetable for liftoff to October, from September.

Among the reasons LaVorgna gave for adjusting his forecast was that financial markets aren't yet expecting a hike.

Fed funds futures imply that the probability of the central bank raising interest rates on Thursday sits at 30 percent.

"If they basically hike this week, this would be the first time in 20 years the Fed is hiking rates without the market having priced in 100 percent at the very start of a Fed hiking cycle, so I think this will be a big surprise for the market," said Woo.