Fuzzy Logic

We can’t do good public health if we don’t recognize it when we see it. Without an adequate definition, the unique lens of public health is fuzzy.


In writing about the future of public health in 1988, an IOM committee pronounced public health to be “in disarray.” Part of the problem was a generally fuzzy idea of what public health is. Here is the definition that the committee in the end agreed on: the role of public health is “fulfilling society’s interest in assuring conditions in which people can be healthy.”


Notice how different this conception is from other definitions of public health, for example:

• the CDC (“the science of protecting and improving the health of families and communities through promotion of healthy lifestyles, research for disease and injury prevention and detection and control of infectious diseases”),

• the APHA (“Public health promotes and protects the health of people and the communities where they live, learn, work and play”)

• the ASPPH (Public health protects and improves the health of individuals, families, communities, and populations, locally and globally).


Oddly, only the WHO explicitly incorporates the IOM definition of public health.


The difference between “assuring conditions in which people can be healthy” and “improving health” is huge. If you want to improve health, it really sounds like you have to get individuals to change their behavior. Note the CDC’s emphasis on promoting healthy lifestyles for example. Not only is changing individual behavior hard, but it puts the emphasis on the wrong place for reasons ethical, conceptual, and operational.


These different understandings of public health have big ethical implications. If our job is, in effect, to get people to exercise more, we’re substituting our judgment about what has value for the individuals’ own judgment.

A protected bike lane in NYC

Now, if health education were all we’re talking about, then no big deal. But the fact is, health promotion often goes way beyond education into the realms of soft coercion familiar to marketing, spin, and behavioral economics. Pretty soon we get into the dangerous territory of violating individual autonomy and dignity. Maybe not everyone wants the health benefits of more exercise and avoiding unpasteurized milk. Is it any wonder that conservatives are outraged that Michelle Obama is trying to make them drink water?


The fuzzy definition of health leads to big problems. If we acknowledge that public health should start by recognizing and preserving individual autonomy and dignity, but we define public health in a way—improving health outcomes—that may not be shared as a common value, we’re in a bind. Our goal is to accomplish a change that maybe we don’t want to accomplish. Not only do we get conceptual confusion over how far public health can or should go, we’ll have no idea of when we’ve succeeded. Is public health success the maximal health of a submissive population, or the more variegated and nuanced health of a community that is engages in defining and pursuing health on its own terms?


But the biggest problem with the usual definitions of public health is operational. If the job is to change behavior, or even to improve health, then the natural place to intervene is with the individual. The question is—how can we get you to ride your bike more, quit smoking, and eat broccoli. But what if individual choice is not, after all, the major driver of health? What if instead of the choice, it’s the choice set? You can nag me all you want about getting more exercise, but put in a protected bike lane and I’m off to the races.


Public health is about the conditions in which people make choices, not about the choices themselves. The IOM got it right some 30 years ago, but public health is still fuzzy on what its core mission is.


If we stick with the IOM’s definition of public health as assuring conditions in which people can be healthy, we avoid disarray. We preserve autonomy and dignity, we know when we’ve succeeded, and most importantly we retain the emphasis on the structural factors that really drive population health outcomes.

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