ABSTRACT
If advice as apparently innocuous and “theoretically sound” as recommending a babys sleeping position can be lethal, there is clearly no room for complacency among professionals about their potential for harming those whom they purport to help. Evidence of collective uncertainty about the effects of their policies and prac tices should prompt the humility that is a precondition for rigorous evaluation. In a moving account, Judith Gueron (2002, 27-28) has reported how professionals delivering an education and training program for high school dropouts agreed to a randomized trial to assess its effects, in spite of their concern that this might fail to find any beneficial effects of their work. (In fact, the results of the trial were posi tive and led to a fifteen-site expansion serving hundreds of disadvantaged youth.)
A recent example from medical research illustrates the importance of remaining uncertain about the effects of an intervention until reliable evidence is available showing that it has at least some beneficial effects that outweigh negative effects (Freed et al. 2001). There have been reasons to hope that transplantation of fetal tissue into the brains of people with Parkinson s disease can improve the symptoms of that distressing condition. Accordingly, a randomized trial comparing fetal implants with placebo surgery was done to assess whether these hopes were borne out by experience. Not only did the study fail to detect any beneficial effects of the implants; it eventually showed that they seemed to cause a serious deterioration in symptoms in some patients.
