“LET'S get something out of the way up front,” said a firm President Barack Obama at the start of his speech to the NAACP’s national conference in Philadelphia on Tuesday. “I am not singing today.” His heartfelt eulogy in Charleston last month, which he closed with a soulful rendition of "Amazing Grace", was still fresh in the minds of his audience, but the president had come to talk about policy, not faith. In a mostly serious, occasionally moving and ultimately sprawling 45-minute speech, Mr Obama held forth on the state of criminal justice in America. It is an aspect of American life that remains, in his words, “a source of inequity that has ripple effects on families and on communities and ultimately on our nation.” After rattling off disturbing statistics about the country’s incarceration rate, which is the highest in the world and riddled with racial discrepancies, the president offered some solutions. His laundry list included sentencing reforms that would increase the discretion available to judges and prosecutors and either reduce or eliminate mandatory minimums. He called for changes to prisons that would reduce abuse, overcrowding and the use of solitary confinement, and increase job-training and drug-treatment programmes. He wants to restore voting rights to ex-felons and make it easier for ex-convicts to get jobs. He also proposed more investments in pre-school education, more humane community policing and more jobs for teenagers.

It time for Barack Obama to take on the residual problems of race in America

These goals are all admirable, but they read more like a wish list from a late-term president than a practical agenda. Mr Obama also seemed quick to confuse what makes sense with what makes for an attractive soundbite. To wit: “We’re about to get into a big budget debate in Washington,” he said. “What I couldn’t do with $80 billion! It’s a lot of money.”

The $80 billion Mr Obama referred to is America’s annual corrections budget. That chunk of change might instead be used to fund universal pre-K for every 3- and 4-year-old, he opined, or to build bridges or double the salary of every high-school teacher. It could even be used, he said, to eliminate tuition at every public college and university. This won over the crowd, but it loses logically. That $80 billion is not up for grabs. Mr Obama himself readily admitted that “we need to be honest: there are a lot of folks who belong in prison.” The majority of state prisoners (54%) are behind bars for violent felonies. Some savings can and should be made, but they will not be on the order of magnitude the president implies, particularly as the least dangerous inmates—those likely to be released first—are often the cheapest to house, and quite a few of his ideas, such as better programming in prisons, cost money.

Mr Obama’s push for federal-sentencing reform aside, most of America’s imprisonment takes place at the state level. So the real work of reducing mass incarceration falls to governors, police chiefs, sheriffs, prosecutors, judges, state legislators and activists around the country. The real challenge for them, then, is to convince voters of the benefits of reducing mass incarceration.

Some of these gains fit neatly on a balance sheet. In Texas, for example, a tweak to the state’s probation system in 2005 saved taxpayers nearly $120m. But other benefits, while considerable, are harder to quantify. They involve reuniting families and restoring communities. “Around 1m fathers are behind bars. Around one in nine African American kids has a parent in prison,” Mr Obama said. “What is that doing to our communities? What’s that doing to those children?”