The problem is that policies that ignore character and behavior have produced disappointing results. Social research over the last decade or so has reinforced the point that would have been self-evident in any other era — that if you can’t help people become more resilient, conscientious or prudent, then all the cash transfers in the world will not produce permanent benefits.

Walter Mischel’s famous marshmallow experiment demonstrated that delayed gratification skills learned by age 4 produce important benefits into adulthood. Carol Dweck’s work has shown that people who have a growth mind-set — who believe their basic qualities can be developed through hard work — do better than people who believe their basic talents are fixed and innate. Angela Duckworth has shown how important grit and perseverance are to lifetime outcomes. College students who report that they finish whatever they begin have higher grades than their peers, even ones with higher SATs. Spelling bee contestants who scored significantly higher on grit scores were 41 percent more likely to advance to later rounds than less resilient competitors.

Summarizing the research in this area, Reeves estimates that measures of drive and self-control influence academic achievement roughly as much as cognitive skills. Recent research has also shown that there are very different levels of self-control up and down the income scale. Poorer children grow up with more stress and more disruption, and these disadvantages produce effects on the brain. Researchers often use dull tests to see who can focus attention and stay on task. Children raised in the top income quintile were two-and-a-half times more likely to score well on these tests than students raised in the bottom quintile.

But these effects are reversible with the proper experiences.

People who have studied character development through the ages have generally found hectoring lectures don’t help. The superficial “character education” programs implanted into some schools of late haven’t done much either. Instead, sages over years have generally found at least four effective avenues to make it easier to climb. Government-supported programs can contribute in all realms.

First, habits. If you can change behavior you eventually change disposition. People who practice small acts of self-control find it easier to perform big acts in times of crisis. Quality preschools, K.I.P.P. schools and parenting coaches have produced lasting effects by encouraging young parents and students to observe basic etiquette and practice small but regular acts of self-restraint.