CHEBEAGUE ISLAND — In a recent Maine Voices column, Daniel C. Bryant, M.D., of Cape Elizabeth argued that various conservative principles are consistent with Medicare for All. He cites Otto von Bismarck, Friedrich von Hayek, Ronald Reagan and Warren Buffett, as well as the Bible and a study that showed that health insurance resulted in fewer deaths than lack of insurance.

Such an approach, he says, would free workers from dependence on workplace health benefits, and allow some now limited by illness to enter the workforce. As he puts it, like conservatism, this system is all about freedom.

However, in thinking about Medicare for All, there are other issues to keep in mind. In particular, what is the source of disease? Although the study referenced by Bryant implies it is lack of health care, a more basic analysis points to three other sources.

Many diseases are the result of our genetic makeup. Forty-eight such diseases are listed by the National Human Genome Research Institute, including cystic fibrosis, hemophilia and Huntington’s disease.

Other diseases have environmental causes, such as lead paint, contaminated food and air pollution. The Environmental Protection Agency recently lifted a ban on the insecticide chlorpyrifos, which has been linked to learning and memory problems.

 Still other diseases affect individuals because of their own behavior, such as complications due to obesity (Type 2 diabetes, some forms of cancer, cardiovascular problems); emphysema from smoking (another cause is air pollution), and death resulting from using addictive drugs.

As a general principle, it makes sense to address the cause of disease, rather than trying to ameliorate the outcomes of those causes via drugs, genetic therapy or other interventions. The three sources of disease mentioned above are all mediated by means of human behavior: Deleterious genes are passed on by means of sexual activity; pollution derives largely from business owners allowing toxins to be emitted into the water or air, and individuals can fail to care for their own bodies by not exercising or by consuming certain foods.

Given that certain behaviors give rise to costs, it makes sense to apply some of that cost to the individual in order to reduce the associated behavior; call this commensurate feedback. For example, cystic fibrosis costs this country about $1.1 billion a year. Medicare for All would extract this money from individuals and businesses based on their incomes, and cover the cost of treatment for individuals with the problem. Carriers would have no incentive to limit their reproduction. In the long run, Medicare for All would result in more people with cystic fibrosis, at higher costs, than would occur if carriers had to shoulder some of the fiscal burden.

No doubt some will say this is a form of eugenics, and so is unacceptable. But there is no forced sterilization at work. People would simply be required to compensate, at least to some extent, for the costs they impose on others. There is nothing intrinsically problematic with reducing the incidence of deleterious genes. (If there were, some would presumably argue that we should increase their frequency.)

In terms of environmental causes of disease, pollution is often treated as a negative externality by businesses: a cost that businesses impose on others. Requiring that those who pollute cover the health costs of doing so would reduce that behavior, benefiting all of us. A carbon tax (related more to global warming than to disease, per se) is consistent with commensurate feedback.

When it comes to how individuals affect their own health, economists Anne Case and Angus Deaton report that longevity among non-Hispanic whites without college degrees is decreasing, because of drugs, alcohol and suicide. It is certainly possible that health care costs that do not depend on how one treats one’s own body are a case of moral hazard: the tendency to downplay risks against which one is insured. Medicare for All would exacerbate the problem; commensurate feedback would presumably reduce it. Ideally, we should all be taking responsibility for our own health.

Medicare for All is alluring, but the only cure for disease involves addressing the behavior that perpetuates it. And that, Medicare for All does not do.