When it comes to economics, we spend most of our time thinking about better ways to organize human activity. This is the main purpose of debates about minimum wage, universal health care, deregulation, taxes and other common economic policies. But it’s worth remembering that the condition of the people matters a lot as well — the best policies in the world won’t guarantee prosperity if the bulk of citizens are sick, illiterate or innumerate.

In the 20th century, universal public education and public health measures became standard policy in every developed country. That increased the capabilities of the workforce — what economists call human capital — immensely. Factory workers could read instructions, office workers could calculate revenues and costs, and people throughout society were mostly freed from the scourge of diseases like polio, whooping cough and tuberculosis. This was a huge win for developed nations, and for human quality of life.

But in the 21st century, rich countries’ economies depend more and more on knowledge industries like technology, finance and business services. Even outside of those industries, almost every worker now has to know how to use office-productivity software, interact with websites or perform other complex tasks. In this new world, humans are being asked to think all the time.

That means US policy makers need to be looking at better ways to upgrade the mental capabilities of the labor force. Unfortunately, a number of things interfere with Americans’ ability to think clearly.

The biggest threat to clear-headedness comes from drugs. The twin epidemics of opioid-painkiller dependence and heroin abuse destroy people’s lives and harm productivity. There is a strong correlation between opioid use and unemployment, and it’s no great stretch to assume that the former helps cause the latter.

A second, much-discussed problem is lead pollution. A flood of research is finding that even small amounts of lead exposure in childhood can lead both to worse academic performance later in life, and to more criminal behavior.

Furthermore, recent evidence suggests that American children are far more exposed to lead than most people realize. Lead paint contaminates soil, lead pipes contaminate drinking water, and a variety of commercial products from cosmetics to electronics contain bits of lead. The US is allowing its people to be poisoned with heavy metals, and both their intelligence and their self-control is being degraded as a result.

But drugs and lead aren’t the only forces preventing Americans from being able to think clearly. Poverty is another. Everyone knows that the US is a very unequal country, but few think about the damage that causes to American minds. A growing body of researchshows that poor people have different brain structures from other people.

Mental problems can and do cause poverty, of course, but poverty also exposes people to many of the forces that are known to cause post-traumatic stress disorder — violence and unstable family situations — in addition to brain-damaging malnutrition. Let’s hope that new long-term studies will clarify just how much poverty damages the brain, although the mechanisms are already pretty obvious.

Violence in general probably causes lots of long-term harm to the minds of American children. The US as a whole has a high murder rate for a rich country — 4.2 homicides per 100,000 people, about three times as high as France or the UK. 

When all these factors are added up, they represent a severe threat not just to Americans’ quality of life, but to the productivity of the US workforce. Policy makers, economists and other intellectuals should start thinking more about how to beat back this multipronged assault on national clear-headedness.

Opioid prescriptions should be curbed and monitored more closely. Policies from countries such as the Netherlands should be copied to beat back the heroin menace. A nationwide program of lead abatement should scour the metal from US soil, drinking water and commercial products. A more robust social safety net should be implemented to cushion the stress and deprivation of poverty. Community policing strategies should be implemented to cut crime by building trust between cops and communities.

In the 20th century, government saved us from disease and illiteracy; in the 21st, it needs to help us clear our minds. 

Bloomberg View