Common Factors and the Pinhole Fallacy

I am writing about a logical fallacy that I have been calling a “pinhole fallacy” and I would like to know what it is actually called.

The general form is this: First, a lot of empirically generated data is summarized into a few ideas, then those few ideas are then used to generate a lot of ideas which are assumed to be empirically generated because of their apparent origin in empirically derived data.

I’ve actually been calling it “family therapy’s Lambert-pinhole common factors fallacy” because I came across it in this form (greatly simplified, of course):  There has been a lot of research into what effective (individual-based) therapeutic modalities have in common. As far as I can tell, this research is pretty good, on the whole, though it has not come close to showing anything like causation, mediation, or mechanisms of change in therapy.  A guy named Lambert wrote a paper about this evidence, summarizing all of the many elements common to therapy modalities into four broad categories: the therapeutic relationship, model-specific factors, hope and expectancy on the part of the client, and extratherapeutic factors. Many writers in family therapy has gone on to take his summary as new data, creating new models of therapy based on the four-common-factor idea, and apparently thinking of this common-factor model as empirically generated and supported.

This process relies on a “hasty generalization” fallacy, and also a “post hoc” fallacy, but it seems to me that it should have its own name. What is it, logicians?

(First published as “Know Your Logic? Help Me Out!”  May 7, 2011, on Nathen’s Miraculous Escape.)

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