Doctoral Student: David Johns

Graduation Year: 2019
Degree/Concentration: PhD/History
Dissertation: "Good Evidence, Bad Evidence: Science, Ethics, and the Politics of Making and Unmaking Public Health Policies"
Sponsor: Prof. Ron Bayer 

WHAT WAS YOUR DISSERTATION TOPIC AND RESEARCH?

My dissertation examined the role of scientific evidence in public health decision-making, the history of the evidence-based movement, and the extent to which policies and practices in our discipline can be said to be evidence-based in the conventional sense. In general I found that while the question of “what the science says” is nearly always central to policy discussions, decision makers frequently confront situations in which the available research on pressing public health challenges is fragmentary and hardly sufficient to indicate just what to do. In part that is simply due to the nature of our business and the imperative to respond to urgent and emerging public health problems of uncertain severity and etiology. But it means politics, values, cost considerations, “common sense,” and historical and contextual factors will play powerful and often decisive roles in the policy process. There is a fundamental tension in the fact that public health decision makers must sometimes take precautionary action in the absence of strong evidence (e.g., to confront novel potential environmental toxins or disease threats) and our desire for interventions to be anchored in strong evidentiary warrants so that we aren’t chasing ghosts. So the “evidence-based” mantra doesn’t really capture how decisions are made or how they should be made; it’s more of an aspirational concept but one that is misleading and misguided, in my view, both descriptively and prescriptively. 

WHAT MADE YOU INTERESTED IN PURSUING THIS WORK? WHY DO YOU ENJOY IT?

I have always been in interested in controversies in science and public health and how they begin and end. My dissertation includes a number of case studies that captured my imagination during my graduate studies and time working with SMS’s wonderful Center for the History & Ethics of Public Health: the long and bitter controversy over the role of salt consumption in cardiovascular disease; the emergence of the low-fat campaign and its later dismantling and partial replacement with initiatives aimed at reducing intake of sugar; the rise and fall of the “counseling and testing” paradigm for HIV prevention at the Centers for Disease Control and Prevention. As a historian and journalist I love the sense of adventure that comes with undertaking probing investigations, and I think it is important to grapple with the history of contentious public health topics, such as diet and nutrition, where there is an impression that there has been too much flip-flopping and the credibility of the experts is at stake. 

HOW HAS THE “SMS LENS” (SEEING PUBLIC HEALTH AS EMBEDDED IN SOCIAL/CULTURAL/ECONOMIC/POLITICAL CONTEXTS) INFLUENCED YOUR PROFESSIONAL ATTITUDES AND APPROACHES IN ADDRESSING ISSUES IN YOUR WORK? 

All of my work is grounded in the understanding that both the burdens of disease and illness in our society and the public health policies we devise to address them are profoundly shaped by social forces and political choices, and that by studying how those forces took shape we can better position ourselves to promote population health, social justice, and human flourishing. I am particularly interested in how social and historical forces shape what is known and what is unknown in the health sciences. The knowledge we have is usually the knowledge we have purchased (e.g., genomics, precision medicine) – irrespective of whether it is actually valid and useful for public health – while the knowledge we do not have (e.g., obesity prevention, gun violence) often lies in areas that have not been prioritized, have been obscured and neglected because of prevailing patterns of bias or discrimination, or are heavily guarded by powerful interests. The use of historical methods and the SMS lens can deepen our understanding of how evidence and knowledge are embedded in social, political, and temporal contexts.

HOW HAVE YOUR INTERESTS IN PUBLIC HEALTH CHANGED (OR NOT) SINCE YOU WERE AT MAILMAN?

I have stuck to my guns more or less. (Not my literal guns: that's just an expression!) Although I have moved into a variety of new arenas – the history of the evidence-based movement, for example – my focus from the beginning has been on the history and ethics of public health controversies, how we know what we think we know about “what works” in public health, how decision makers can move from evidence to action, and how difficult it can be for agencies to unwind policies that are no longer wanted. I have always been a bit of a tumbleweed, moving from topic to topic, but in general I’m interested in the politics of evidence and knowledge. I also continue to believe that writing for a popular audience is important and rewarding, and plan to continue such undertakings throughout my career. 

WHAT DO YOU FORESEE IN THE NEXT 50 YEARS OF PUBLIC HEALTH?

I’m not very good at predictions, but what the heck: I’m hopeful that proposals such as the “Green New Deal” bespeak an ascendant boldness among progressives to contemplate the kinds of ambitious programs we need to address fundamental issues of equity and justice and restore faith in the government’s ability to “do stuff” and provide for the general welfare. Such broad scale initiatives, even if they don’t immediately go anywhere, can open up an opportunity to talk about social determinants, the differences between health and health care, poverty and stigma and economic opportunity, and all of the things we think about in SMS. I actually think we will eventually pull off Medicare For All (or maybe Medicaid For All). Then there are some concrete problems on which I think we can make progress. Currently the leaders of the gun lobby appear to be arranging themselves into a circular firing squad in face of lawsuits and investigations; the aftermath might provide an opening for action on gun safety. I think we should be prepared to accept incremental progress and a reduction of harm. The obesity challenge, on the other hand, strikes me as more complicated. Additional confrontation with the food industry appears inevitable, but I don’t think soda taxes and the like are going to achieve much on their own. I think precision medicine is going to be a bust. But on the plus side, that means we will be able to abandon the confusing phrase “precision public health.” In the evidence realm, I think analyses based on “big data” are going to begin to challenge the RCT as the “gold standard.”