If true, this would help account for why the economy has notched mediocre growth since the turn of the century, with the exception being a brief period of the housing bubble.

It would also have big implications for Fed policy. It would imply that, under the current economic arrangement, the nation’s potential economic growth is lower than it might otherwise be. Which implies that it would be dangerous for the Fed to try to seek growth much faster than that using monetary policy, as doing so might unleash inflation, financial bubbles or both.

A second area in which monetary policy interacts with inequality — and which Ms. Yellen also leaves unaddressed — is the role of the Fed’s easy money policies in encouraging inequality.

For the last five years of economic expansion, Congress has been unwilling to use fiscal policy to try to encourage faster growth. That has left the Fed as the only game in town, and the Bernanke Fed again and again turned to quantitative easing and ultralow interest rate policies to try to shock the economy into speedier expansion. (Ms. Yellen was the No. 2 official at the Fed for most of this time, and helped engineer the policies).

But this has contributed to an imbalanced form of growth in the United States. Many of the first-order effects of the Fed’s bond buying have been, for example, to drive up the stock market and to help lower mortgage rates. Because stocks are disproportionately owned by the wealthy and the upper middle class have been in best position to refinance their mortgages, the benefits of Fed policy for middle and low-income workers have been more indirect.

It is unclear what that means for the proper course of monetary policy. If quantitative easing policies led to stronger overall growth that are the reason employers are adding more jobs, then the trickle-down benefits for ordinary workers are still meaningful. But Ms. Yellen did not address in her speech whether she agrees with the premise that a Fed-driven economic recovery has contributed to inequality, and if so what it implies for her agency.