At the same time, Democrats seem finally to have taken on board something political scientists have been telling us for years: adopting “centrist” positions in an attempt to attract swing voters is a mug’s game, because such voters don’t exist. Most supposed independents are in fact strongly aligned with one party or the other, and the handful who aren’t are mainly just confused. So you might as well take a stand for what you believe in.

But the party’s change isn’t just about politics, it’s also about policy.

On one side, the success of Obamacare and related policies — millions covered for substantially less than expected, surprisingly effective cost control for Medicare — have helped to inoculate the party against blanket assertions that government programs never work. And on the other side, the Davos Democrats who used to be a powerful force arguing against progressive policies have lost much of their credibility.

I’m referring to the kind of people — many, though not all, from Wall Street — who go to lots of international meetings where they assure each other that prosperity is all about competing in the global economy, and that this means supporting trade agreements and cutting social spending. Such people have influence in part because of their campaign contributions, but also because of the belief that they really know how the world works.

As it turns out, however, they don’t. In the 1990s the purported wise men blithely assured us that we had nothing to fear from financial deregulation; we did. After crisis struck, thanks in large part to that very deregulation, they warned us that we should be very afraid of bond investors, who would punish America for its budget deficits; they didn’t. So why believe them when they insist that we must approve an unpopular trade deal?

And this loss of credibility means that if Mrs. Clinton makes it to the White House she’ll govern very differently from the way her husband did in the 1990s.