The evidence that evidence-based medicine omits
Related Experiment Video
Updated: May 17, 2026
Evidence-based Knowledge Synthesis and Hypothesis Validation: Navigating Biomedical Knowledge Bases via Explainable AI and Agentic Systems
Published on: June 13, 2025
Brendan Clarke1, Donald Gillies, Phyllis Illari
1Department of Science and Technology Studies, University College London, UK.
Insights
Evidence of mechanisms should be prioritized equally with evidence of correlation in evidence-based medicine (EBM). Understanding causal mechanisms enhances the reliability of scientific claims and research validity.
Area of Science:
- Philosophy of Science
- Medical Research Methodology
Background:
- Current evidence-based medicine (EBM) hierarchies prioritize correlational evidence (e.g., randomized controlled trials) over mechanistic evidence.
- This hierarchy can be problematic as correlational evidence is susceptible to confounding factors.
Purpose of the Study:
- To argue for the equal importance of mechanistic evidence alongside correlational evidence in establishing causal claims.
- To extend the critical examination of evidential practices within EBM to include mechanistic evidence.
Main Methods:
- Philosophical analysis of the role of evidence in establishing causation.
- Critique of existing hierarchies of evidence in EBM.
- Argumentation based on the limitations of correlational evidence and the necessity of mechanistic understanding.
Main Results:
- Correlational evidence is an imperfect indicator of causation due to issues like confounding.
- Mechanistic evidence can be crucial for interpreting correlational findings and assessing causal claims.
- Mechanistic understanding is often prerequisite for designing and evaluating studies that yield correlational evidence.
- Generalizing and applying causal claims frequently depends on understanding underlying mechanisms.
Conclusions:
- Mechanistic evidence should be integrated and critically examined within EBM frameworks.
- Elevating the status of mechanistic evidence will strengthen the foundation for causal inference in medicine.
- A more comprehensive approach to evidence evaluation is needed, encompassing both correlation and causation.
Abstract:
According to current hierarchies of evidence for EBM, evidence of correlation (e.g., from RCTs) is always more important than evidence of mechanisms when evaluating and establishing causal claims. We argue that evidence of mechanisms needs to be treated alongside evidence of correlation. This is for three reasons. First, correlation is always a fallible indicator of causation, subject in particular to the problem of confounding; evidence of mechanisms can in some cases be more important than evidence of correlation when assessing a causal claim. Second, evidence of mechanisms is often required in order to obtain evidence of correlation (for example, in order to set up and evaluate RCTs). Third, evidence of mechanisms is often required in order to generalise and apply causal claims. While the EBM movement has been enormously successful in making explicit and critically examining one aspect of our evidential practice, i.e., evidence of correlation, we wish to extend this line of work to make explicit and critically examine a second aspect of our evidential practices: evidence of mechanisms.
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