Miasmas and other mental models

EPID 684
Spatial Epidemiology
University of Michigan School of Public Health

Jon Zelner
[email protected]

Today’s Theme

Mental models, past and present (or at least recent past…)


  • Gold Standards” and other scientific illusions 🧙

  • What did Chowkwanyun & Reed get right? Wrong?

  • If time: Return of the hotspot.

What do you think the implications of this (very) short story are for you and your project?

What’s old is new…

In this paper, I have argued that both the long delays in replacing flawed, miasma-driven approaches to cholera prevention in the nineteenth century and long delays in replacing an exclusively contact-and-droplet model of SARS-CoV-2 prevention with one that includes airborne transmission in the twenty-first had a philosophical explanation in terms of which mental models of reality prevailed and the extent to which scientists and policymakers favoured data over theory. (1)

Intuition pumps are stylized presentations of mental models

As described by the philosopher Daniel Dennett:

Intuition pumps are cunningly designed [thought experiments, which] focus the reader’s attention on “the important” features, and…deflect the reader from bogging down in hard-to-follow details. (2)

A not-so-metaphorical intuition pump

Well thought-out mental models let us:

  • Characterize meaningful relationships between physical environments, social environments, and health.
  • Reveal the appropriate scale of analysis and intervention.
  • Explore the implications of geographically varying policies.
  • Why are mental models so critical to how we understand and intervene in epidemics?

    • What is evidence-based medicine, and what is Greenhalgh’s critique of its role in the COVID-19 pandemic?

    • What weaknesses does she highlight in the Danamask RCT?

    • What alternative sources of evidence does she argue should have been considered sooner?


    Small scale spatial data provided compelling evidence for the droplet theory of SARS-CoV-2 transmission

    Does this echo anything from The Ghost Map?

    Why didn’t mechanistic evidence dislodge the droplet-only perspective on SARS-CoV-2 transmission?

    Relationship between voice volume and aerosol production (From Asadi et al. 2019)

    EBM’s hierarchy of evidence

    • What is meant by ‘risk of bias’?

    • Quality of evidence?

    • Where would Snow’s explorations fit in this hierarchy?

    A version of the ‘evidence pyramid’ central to the philosophy of evidence-based medicine

    Which approach to aggregating evidence fits best with the spatial perspective?

    Brick Wall: Collecting similar forms of evidence to test the strength of a hypothesis

    Stone Wall: Collecting heterogeneous evidence to develop a robust and comprehensive explanation

    Reflecting on “Racial Health Disparities and Covid-19 — Caution and Context”

    • What are Chowkwanyun and Reed’s key concerns about the characterization of prevailing mental models of racial health disparities?

    • How does spatial analysis figure into their concerns? Is there a world in which is it is part of the solution?

    • What solutions do they propose?

    • To what extent have their worst-case predictions come to fruition?


    Next Time

    • Starting to think about spatial vs. place-based approaches.


    Greenhalgh T. Miasmas, mental models and preventive public health: Some philosophical reflections on science in the COVID-19 pandemic. Interface Focus [electronic article]. 2021;11(6):20210017. (https://royalsocietypublishing.org/doi/10.1098/rsfs.2021.0017). (Accessed January 11, 2022)
    Dennett DC, Crawford J. Intuition Pumps and Other Tools for Thinking. Unabridged edition. Brilliance Audio; 2014.