Existential approach has some very attractive and effective techniques, however, some people have referred to this theoretical approach as a philosophy, not a treatment. While an argument can be made relative to epistemology and methodology, it is obvious to me that the existential approach has not been subjected to tests (e.g., randomized clinical trials), usually requirements that are needed to meet the criteria for a scientific approach. So my question is how you reconcile the existentialist approach versus an evidence-based treatment, knowing that the psychology field is moving towards the implementation of evidence-based interventions?
Existential therapy is philosophy-based of course, and since philosophy is not science, the approach pairing it into counselling makes it look like pseudo-science. Yet, in the field of clinical psychology, existential-therapy is seen as a model for evidence-based practice, primarily because the approach allows for quantifying how effective or appropriate the treatment was in treating disorders. A good study that shows this is that of Hoffman, Dias & Choi-Soholm (2012), entitled "Existential-Humanistic Therapy as a Model for Evidence-Based Practice" of Saybrook University. The authors agree that those who practice existentialist therapy are "oppos[ing] assessing therapy effectiveness in a reactionary manner, objecting to any external oversight or critique of their practice...due to epistemological, practical,and value-based reasons." What this means, in practical terms, is that existential therapists do not like critique primarily because, like you, they also see that what they are using as application to treatment is philosophy and this is open to critique by those who go down the scientific and medical route. What Hoffman, et. al. are saying in this study is this - existential therapy is one of the best models of evidence-based practice. You are right in saying that the methods that existentialists use have not been subjected to assessments to ascertain their 'scientificity;' they certainly would not agree to be subjected to randomized clinical trials for sure.
Understanding the Debates
One thing that you have to remember in the practice of psychology is the divide between clinicians and experimentalists. I believe that in your view of the issue, you think a lot like an experimental psychologist - dealing with the science and exploring experimental methods to study human behavior to come to understand it. Clinical psychologists, meanwhile, are much more focused on applying psychological principles to 'fix' disorders, to help individuals suffering from a variety of psychological, emotional and behavioural issues. Essentially, the difference between them is that clinical psychologists are like ...
The solution discusses the existentialist approach vs. an evidence-based treatment.