The Epistemic Fallacy in Physical Therapy

A Call to Clinical Inquiry to bring ontology into focus

In physical therapy, we pride ourselves on being evidence-based practitioners. We look to research to inform our decisions, carefully evaluating outcome measures, diagnostic tools, and treatment approaches. Yet, in our pursuit of knowledge, we can sometimes fall victim to a subtle but profound error: the epistemic fallacy.

The epistemic fallacy occurs when we confuse how we know something (epistemology) with what actually exists (ontology). In physical therapy, this often manifests as assuming that the tools we use to measure or understand a phenomenon fully capture its reality. This conflation can limit our thinking, reduce the depth of our clinical reasoning, and ultimately impact patient care.

Here are some examples of the epistemic fallacy in physical therapy:

1. Over-reliance on outcome measures:
   Standardized tools like the Oswestry Disability Index are helpful, but they are proxies, not the full picture of a patient’s recovery. A patient may achieve a "better score" while still experiencing significant challenges that the tool cannot capture.

2. Reduction of pain to biomedical factors:
   Pain is often treated as a purely biomechanical issue, ignoring the psychological and social dimensions that are equally real but harder to measure. This reductionist approach can fail to address the complexity of the patient’s experience.

3. Mistaking correlation for causation:
   Studies showing that increased core strength correlates with reduced back pain do not necessarily mean one causes the other. Assuming so overlooks other possible factors, such as psychosocial influences or natural healing processes.

4. Blind trust in diagnostic imaging:
   Imaging can reveal structural abnormalities like disc herniation or tendon tears, but these findings often occur in asymptomatic individuals. Assuming imaging always reflects the source of symptoms conflates observation with clinical reality.

5. Exclusive reliance on randomized controlled trials (RCTs):
   RCTs are invaluable, but they represent group averages. Applying their findings indiscriminately assumes all patients fit into the average, disregarding individual variability and the importance of clinical judgment.

6. Equating biomechanics with function:
   Movement analyses may show deviations from "normal" patterns, but patients often adapt and thrive with altered mechanics. Pursuing "normalcy" in biomechanics isn’t always necessary—or beneficial—for optimal function.

Photo by Tim Johnson on Unsplash

Why Clinical Inquiry Matters

The epistemic fallacy is a reminder that clinical practice is not just about applying evidence but about critically engaging with it. As physical therapists, we must go beyond the limits of what is measurable to consider the broader, messier reality of our patients' lives. This requires a mindset of clinical inquiry: the ability to question assumptions, integrate diverse perspectives, and remain open to new ways of thinking.

That’s why I’ve created the Clinical Inquiry Fellowship, a program designed to cultivate these skills in the next generation of physical therapists. Fellows will learn to navigate the complexities of evidence, challenge the boundaries of traditional practice, and contribute to the evolving understanding of clinical reasoning.

The Fellowship emphasizes the critical importance of epistemology and ontology in clinical practice. By engaging deeply with concepts like the epistemic fallacy, participants will develop the tools to avoid these common pitfalls and elevate their decision-making. This program is about more than academic knowledge—it’s about transforming how we think, practice, and advance our field.

Join the Conversation

If this resonates with you, I encourage you to subscribe to Peripatetic PT for more insights into clinical reasoning, evidence-based practice, and the philosophy of physical therapy. Whether you’re a student, clinician, or researcher, the Clinical Inquiry Fellowship offers a unique opportunity to deepen your understanding and make meaningful contributions to our profession.

Together, let’s move beyond the limitations of the epistemic fallacy and toward a richer, more nuanced practice of physical therapy—one that truly reflects the complexity of our patients and the world they live in.

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Interested in learning more?
Check out the full details of the Clinical Inquiry Fellowship here. Applications are now open, and I’d love to have you join this journey toward deeper clinical inquiry.