When we approach research in rehabilitation science, we’re taught that good work begins with a theoretical foundation—a conceptual framework, a model, something that anchors our thinking. Theory, we’re told, is the “bedrock for understanding and prediction” (Whyte & Barrett, 2012). And while it’s true that researchers can conduct studies without a defined theoretical framework, using theory helps us select relevant variables, create structure, and make sense of both expected and unexpected results (Ivey, 2015).

In other words: theory is the scaffolding that keeps the research house from collapsing in on itself.

But theory does more than organize ideas.
In a multidisciplinary field like rehabilitation science—where medicine, psychology, engineering, education, neuroscience, and social sciences all converge—shared theories help create cohesion (Jahan & Ellibidy, 2017; Siegert, McPherson, & Dean, 2005). Rehab sciences frequently borrow theories from one another because no single unifying theory exists to describe how all the interdisciplinary parts fit together. Whether such a unifying theory is even possible is debatable. What is not debatable is that theory, in its many forms, helps guide translation from research to practice, clarifies what influences outcomes, and supports the evaluation of implementation (Nilsen, 2015).

But here’s the catch: theory is a guide, not a cage.

Ivey (2015) warns us against becoming “theoretically rigid,” reminding us that “there is too much at risk in research” to cling to assumptions without scrutiny. The heart of scientific inquiry lies in comparing what we believe to be true with what repeated evidence actually shows.

That resonates deeply with me as a clinician.
If I had abandoned every idea simply because an older theory deemed it “ineffective,” I would have missed countless strategies that have produced meaningful outcomes for patients. Sometimes clinical intuition reveals something the existing literature has not yet articulated. At other times, theory helps explain why an unexpected clinical observation matters. And occasionally, practice reveals a phenomenon so consistent and so useful that it becomes the foundation for a new theory altogether.

This is why theory must remain a construct, not a commandment.
Its job is to orient us—not confine us.

Where Does Occupational Therapy Fit in This Conversation?

Occupational therapy is known for being a top-down profession. In theory, that aligns us with constructs like enablement theory (Whyte, 2014). But in practice? OT has always drawn from diverse theoretical lineages: psychology, neurology, biomechanics, sociology, anthropology, medicine, and increasingly—complex systems and neuroscience.

It is simply untrue that OT can function solely through occupational constructs.
Our domain explicitly includes body functions, body structures, and performance skills, each contributing to the therapeutic process ("Occupational Therapy Practice Framework: Domain and Process—Fourth Edition," 2020). Ignoring that reality would mean ignoring our own scope.

And here’s where the tension shows up:

• The medical model is still the dominant currency in reimbursement, acute care, rehab, and payer decision-making.

• The social model correctly highlights environment, discrimination, and participation—but does not fully guide clinical intervention.

• The biopsychosocial model (Engel, 1977) remains the ideal, weaving together the strengths of both, but healthcare systems are far from fully adopting it.

I personally practice through a biopsychosocial lens because it allows me to represent OT’s full scope: the physical, cognitive, emotional, social, and environmental dimensions of human function. But I also recognize that our medical infrastructure is nowhere near fully biopsychosocial. OT practitioners must navigate that tension daily, pairing occupation-based reasoning with treatment theories that address real impairments.

So, does occupational therapy have a unifying theory?

Not yet.
And maybe that’s okay.

OT’s strength has always been its ability to synthesize: to pull from multiple disciplines, translate across systems, and create interventions that are meaningful, functional, and human. Theories help us organize that complexity—but they do not define the profession. The people and the outcomes do.

References

Ivey, J. (2015). How Important Is a Conceptual Framework? Pediatric nursing, 41(3), 145, 153-153.

Jahan, A., & Ellibidy, A. (2017). A Review of Conceptual Models for Rehabilitation Research and Practice. Journal of Rehabilitation Sciences, 2, 46-53. doi:10.11648/j.rs.20170202.14

Nilsen, P. (2015). Making sense of implementation theories, models and frameworks. Implement Sci, 10, 53. doi:10.1186/s13012-015-0242-0

Occupational Therapy Practice Framework: Domain and Process-Fourth Edition. (2020). Am J Occup Ther, 74(Supplement_2), 7412410010p7412410011-7412410010p7412410087. doi:10.5014/ajot.2020.74S2001

Siegert, R. J., McPherson, K. M., & Dean, S. G. (2005). Theory development and a science of rehabilitation. Disabil Rehabil, 27(24), 1493-1501. doi:10.1080/09638280500288401

Whyte, J. M. D. P. (2014). Contributions of Treatment Theory and Enablement Theory to Rehabilitation Research and Practice. Archives of physical medicine and rehabilitation, 95(1), S17-S23.e12. doi:10.1016/j.apmr.2013.02.029

Whyte, J. M. D. P., & Barrett, A. M. M. (2012). Advancing the Evidence Base of Rehabilitation Treatments: A Developmental Approach. Archives of physical medicine and rehabilitation, 93(8), S101-S110. doi:10.1016/j.apmr.2011.11.040