With the exception of gay rights, no public-policy debate has shifted more dramatically in my adult lifetime than the debate over crime. In 1992, when Bill Clinton flew back to Arkansas to oversee the execution of a mentally retarded African American murderer, the move helped him in New Hampshire’s Democratic primary. In 1994, Clinton’s crime bill—which among other things, expanded the death penalty, encouraged states to lengthen prison sentences and eliminated federal funding for inmate education—garnered the votes of every Democratic Senator except one.

Today, by contrast, Hillary Clinton is loudly repudiating the “tough on crime” policies that she and her husband once championed. Even more remarkably, prominent Republicans are nodding along.

To those who see Hillary’s new crime agenda as a flip-flop, her campaign has a rejoinder: Different policies make sense at different times. As Clinton spokesperson Jesse Ferguson tweeted, “HRC policy on internet might also be different than WJC policy in 1994. Not b/c he was wrong but b/c times change.”

The problem with this argument is that many of the crime policies the Clintons supported in the 1990s were probably wrong even back then. Yes, the crime bill did some good: It put more cops on the street and increased penalties for sex crimes. But it also helped spawn the very “era of mass incarceration” that Hillary now denounces. It’s not just that the bill allocated almost $10 billion in federal-prison construction money. It only allocated it to states that adopted “truth-in-sentencing” laws that dramatically increased the amount of time criminals served. As NYU Law School’s Brennan Center has noted, the number of states with such laws rose from five when the bill was signed to 29 by Clinton’s last year in office. Over the course of Clinton’s presidency, the number of Americans in prison rose almost 60 percent.

All this might—I underscore, might—be justified if such prison expansion produced dramatic declines in crime. But while crime has indeed dropped dramatically—it’s about half what it was at its peak in 1991—the best evidence suggests that locking people up is not the primary reason. After spending close to two years testing 14 different potential causes of the reduction in crime, the Brennan Center this year concluded that “incarceration was responsible for approximately five percent of the drop in crime in the 1990s,” and an even lower percentage since then. A report last year by the National Academies’ National Research Council found that “the growth in incarceration rates reduced crime, but the magnitude of the crime reduction remains highly uncertain and the evidence suggests it was unlikely to have been large.” Even a 2004 investigation by University of Chicago economist Steven D. Levitt, who considers increased imprisonment more effective, only found that it accounted for roughly one-third of the crime drop.

Some might still argue that, as public policy, Clinton’s tough-on-crime policies were necessary. Listening to Hillary’s impassioned speech yesterday at Columbia, however, where she talked about seeing “how families could be and were torn apart by excessive incarceration,” it’s hard to believe she agrees.

But there’s a different, and more perplexing, defense of the Clinton record on crime. It’s that even if Clinton’s policies can’t be justified substantively, they were necessary politically. If he hadn’t embraced a “tough on crime agenda,” Clinton might never have become—or remained—president.

In the late 1980s and early 1990s, when crime rates hit their peak, the issue enjoyed a salience in American politics that is hard to comprehend today. And for Democrats, the consequences of appearing soft were devastating. In 1988, the George H.W. Bush campaign’s most effective (and notorious) ad slammed Michael Dukakis for furloughing murderers in Massachusetts. (A separate ad, by a pro-Bush PAC, made African American furloughed murderer Willie Horton a household name). The most important moment in that year’s debates came when Dukakis, after being asked how he would react if his wife was raped and murdered, gave a bloodless, and politically catastrophic, answer. In January 1994, 37 percent of Americans said crime was the most important issue facing the country. And that fall, Mario Cuomo lost the governorship of New York State to a little-known Republican, George Pataki, who had made Cuomo’s opposition to the death penalty central to his campaign.

In 1992, Bill Clinton faced a far tougher electorate than Hillary will this time around. African Americans, Hispanics, and Asians, who constituted almost 25 percent of the voters in 2012, and Millennials, who also lean disproportionately left on cultural issues, were either in school or in diapers. There’s a reason Clinton reminded voters that year that his nickname was “Bubba.” It’s because in 1992, far more than today, a Democrat who didn’t appeal to Bubbas couldn’t win. And in 1992, being “tough on crime” was critical to getting most Bubbas to give a Democrat a second look.

Was electing Bill Clinton worth it? It’s the kind of question that separates reformist, “pragmatic” progressives from their more revolutionary, anti-establishment brethren. It can’t be answered empirically. It depends on your worldview.

But it’s worth noting that every (relatively) progressive American president has made these brutal, tragic tradeoffs. In 1947, amidst the growing hysteria of the Red Scare, Harry Truman created review boards to investigate the loyalty of federal employees. Upon learning that the Soviets were installing nuclear missiles in Cuba, John F. Kennedy privately mused, “What difference does it make? They’ve got enough to blow us up now anyway.” But politically, he was sure that unless he risked war to get them removed, “[Republican Senator] Ken Keating will probably be the next president.” Upon becoming president, Barack Obama expanded America’s drone attacks, sent more troops to Afghanistan and backed away from closing Guantanamo Bay. For many progressives, myself included, these policies were difficult to swallow. But without them, Mitt Romney might be president.

Should progressives wish, in retrospect, that Bill and Hillary Clinton had never supported the mass-incarceration policies that candidate Hillary is now denouncing? Sure. But to stay honest, they should also admit that without those policies, Hillary probably wouldn’t be a presidential candidate today at all.