Philosophy of Science Considerations for the Evidence-Based
Practice (EBP) Controversy in Psychotherapy
Faculty Mentor: Brent D. Slife, Psychology
The modern age is an age of evidence. A library search of “evidence-based” returns hundreds of
entries: evidence-based auditing, social work, wound management, crime prevention,
educational methods—the list goes on and on. Virtually any discipline or industry is receiving
increased pressure to justify their methods and practices with evidence. Perhaps nowhere is this
pressure more evident than in the healthcare arena, including mental health services such as
Psychotherapy researchers and practitioners agree that psychological practices should be justified
by evidence; however, there has been much disagreement about what qualifies as evidence. A
growing movement, the empirically supported treatment (EST) movement, has insisted that
treatments be empirically validated through the “gold standard” of medical research, the
randomized controlled trial (RCT). Others have argued that psychotherapy is often inconsistent
with a medical-model approach such as the RCT; therefore, other methods of validation are more
appropriate. In the midst of the conflict, in 2005, a Presidential Task Force of the American
Psychological Association (APA) sought to reach consensus on a “middle ground” policy for
APA. A key purpose for the policy was to reflect “the diverse perspectives within the field”
(APA, 2006, p. 273). The result was a policy for evidence-based practice in psychology (EBPP)
that was approved by a near-unanimous vote by APA’s Council of Representatives.
Using the new APA policy as a central document, I investigated the strengths and weaknesses of
EBPP from a philosophy of science perspective. This endeavor involved library research, as well
as attending presentations and symposia at two APA conventions. My central argument, which is
elaborated briefly in this report, is that although the APA policy is a step forward for evidence-
based practice, it contradicts its fundamental goals of objectivity and diversity. In fact, the policy
makes the same fundamental error as the EST movement: it is based upon an implicit framework
that commits a preinvestigatory bias against certain conceptions of evidence and the methods
they imply. Although the APA policy claims to be committed to diversity, its assumptions are
too narrow for it to consider and recognize the legitimacy certain conceptions of evidence.
A primary reason for the narrowness of the APA policy is its failure to explicitly address and
justify its empiricist framework. A likely reason for this omission is the implicit assumption that
empiricism is “a transparent window to objective reality” (Wendt, 2006, p. 91), rather than one
philosophy among many, each with inherit weaknesses and biases. As a result, the Task Force
(APA, 2006) equates “evidence” with “empirical,” without justification, throughout its
explanatory report of the policy. In fact, in the same way that an EST framework restricts
acceptable evidence to a single method (RCT), the APA policy restricts acceptable evidence to a
single epistemology (empiricism).
Ironically, an exclusively empiricist framework is not justified with evidence or rationale; it is
merely assumed a priori. As a result, unobservable (not strictly observable or empirical, yet
experienced) phenomena that are reported by therapists and patients to be essential for effective
therapy (e.g., therapeutic relationship) are either ignored or forced into empirical categories (i.e.,
“operationalized”). In fact, the Task Force explicitly requires for the operationalization of
evidence-based practices (APA, p. 274).
This a priori empiricist assumption ignores the existence of qualitative methods, which were
developed to enable the investigation of unobservable phenomena, without making such
phenomena observable via operationalizations. Although the Task Force includes qualitative
research as an acceptable method, it does so in a marginalized and misunderstood fashion that
exposes the policy’s empiricist framework. For example, in the Task Force’s descriptions of
acceptable methods, the word “subjective” is reserved for qualitative research only, implying that
all other methods are “objective.” These subjective/objective categories make sense only from an
empiricist framework—and “subjective” is clearly the second-class citizen (Wendt & Slife, in
press). More importantly, such categories fail to account for the diverse perspectives within the
entire discipline, including qualitative researchers who do not view their research as a
Considering the failure of the APA policy to achieve its goals of unbiased objectivity and
diversity, Dr. Slife and I articulated an alternative framework for evidence-based practice—
objective methodological pluralism (OMP). Unlike the APA policy, OMP requires an
epistemological pluralism that better considers the epistemological diversity of psychotherapy.
Rather than being driven by a particular method (e.g., RCT) or epistemology (e.g., empiricism),
OMP would be driven by the object of study (hence the term, “objective”) or, in other words,
“the truth of our practical experience” (Slife, 2006). Such a pragmatic framework is modeled
after the philosophy of William James, one of the fathers of psychology. The details of OMP are
beyond the scope of this brief report; in short, OMP is designed to better incorporate the diverse
perspectives of the discipline, and it avoids being driven by a prized method or epistemology.
We are currently developing OMP in further detail, and plan to publish our work.
APA Presidential Task Force on Evidence-Based Practice. (2006). Evidence-based practice in
psychology. American Psychologist, 61, 271-285.
Slife, B. D. (2006, April). A practical alternative to the EBPP framework: Objective
methodological pluralism. Paper presented at the meeting of the Rocky Mountain
Psychological Association, Park City, UT.
Wendt, D. C. (2006). The unevaluated framework of APA’s policy on evidence-based practice in
psychology (EBPP). New School Psychology Bulletin, 4(1), 89-99.
Wendt D. C., & Slife, B. D. (in press). Is evidence-based practice diverse enough?
Philosophy of science considerations [Comment]. American Psychologist, 62.