Medical care has overinvested in screening, to the detriment of human health. It doesn't reduce the overall number of deaths among those who are screened, and there are real human costs to getting ahead of symptoms. Patients are diagnosed with diseases not destined to bother them, and are subsequently harmed by unnecessary treatment, the side-effects of medication and complications of pointless procedures. Many more face abnormal test results, triggering cascades of more testing, procedures, complications and anxiety. Some are told that, while they don't have the disease, they are at "high risk" for it. More generally, screening relies on fear. To persuade asymptomatic people to be screened, they must first be made to worry about diseases they might get in the future. This undermines our sense of well-being, which lies at the very core of health. All of this costs time and money"and a lot of it. Cancer screening alone in the US has been estimated to cost $43 billion annually. For a variety of reasons, I think this is a low-ball estimate: the real number is closer to $100 billion. That kind of money could go a long way toward improving treatment for symptomatic patients or, more broadly, tackling the social determinants of health. And then there is a lot of magical thinking: not only do we assume that more screening will save more lives, but that testing large swaths of the population will somehow ... reduce disparities in healthcare outcomes.