How to gain evidence for causation in disease and therapeutic intervention: from Koch’s postulates to counter-counterfactuals

• Published in: Medicine, health care, and philosophy Vol. 25; no. 3; pp. 509 - 521
• Main Author: Evans, David W.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.09.2022; Springer Nature B.V
• Subjects: Between-subjects design; Causality; Education; Ethics; Infectious diseases; Intervention; Medical Law; Parasites; Pathology; Philosophy; Philosophy of Biology; Philosophy of Medicine; Scientific Contribution; Theory of Medicine/Bioethics
• ISSN: 1386-7423; 1572-8633; 1572-8633
• DOI: 10.1007/s11019-022-10096-x

Researchers, clinicians, and patients have good reasons for wanting answers to causal questions of disease and therapeutic intervention. This paper uses microbiologist Robert Koch’s pioneering work and famous postulates to extrapolate a logical sequence of evidence for confirming the causes of disease: association between individuals with and without a disease; isolation of causal agents; and the creation of a counterfactual (demonstrating that an agent is sufficient to reproduce the disease anew). This paper formally introduces counter-counterfactuals , which appear to have been used, perhaps intuitively, since the time of Koch and possibly earlier. An argument is presented that counter-counterfactuals (disease-preventers) are a useful tool for identifying necessary causes of disease, and sometimes must be used in place of isolation which is not always possible. In addition, a logical sequence of causal evidence for a therapeutic intervention is presented: creating a counterfactual (demonstrating that the intervention is sufficient to change the natural course of a disease), comparisons between subjects in receipt of treatment versus those who are not (typically within a randomised controlled trial, which can quantify effects of intervention), and counter-counterfactuals (treatment-preventers, which can identify the intervention’s mechanisms of action).