Hillary Clinton gave her first big economic speech on Monday, and progressives were by and large gratified. For Mrs. Clinton’s core message was that the federal government can and should use its influence to push for higher wages.

Conservatives, however — at least those who could stop chanting “Benghazi! Benghazi! Benghazi!” long enough to pay attention — seemed bemused. They believe that Ronald Reagan proved that government is the problem, not the solution. So wasn’t Mrs. Clinton just reviving defunct “paleoliberalism”? And don’t we know that government intervention in markets produces terrible side effects?

No, she wasn’t, and no, we don’t. In fact, Mrs. Clinton’s speech reflected major changes, deeply grounded in evidence, in our understanding of what determines wages. And a key implication of that new understanding is that public policy can do a lot to help workers without bringing down the wrath of the invisible hand.

Many economists used to think of the labor market as being pretty much like the market for anything else, with the prices of different kinds of labor — that is, wage rates — fully determined by supply and demand. So if wages for many workers have stagnated or declined, it must be because demand for their services is falling.