Reflection by Tobias Lindstad on N=1
Philosophers often argue that it is virtuous to be informed by psychology. Psychologists however, might accept philosophy as a source of inspiration, but may only reluctantly admit being informed by it. Hopefully, the interdisciplinary spirit of the January-2016 CauseHealth workshop may contribute to change this for the better. After all, the dispositional account of causation, which is an important point of departure for the gathering, raises ground-breaking questions for any health science. This time, more medical scientists, physicians, physiotherapists and philosophers attended the workshop than did psychologists. However, the dispositional account matters no less to psychology, I think. Here are some thoughts about why:
A prevailing idea among psychologists is that in order to make psychotherapy evidence-based one has to prove the relevance of therapeutic models and the effects of specific techniques on a group-level. Thus, hundreds of perspectives, models and theories have been thrown into rivalry competing for the best mean results. However, this idea, that the only proper way to uncover the relevant causes is to observe their regular effects (the regularity view) threatens to throw the baby out with the bathwater. Since statistics does not take individual experiences into account, information about aspects that are relevant in each case are lost. Thus, one size does not necessarily fit all, and we must qualify our services locally and individually in any case.
Fortunately, the regularity-view is not the only one in town. According to a dispositional account, causes may only tend towards their effects, they may not necessitate them and may never result in any observable regularity. Are not our thoughts, feelings, memories, expectations and wants like this? If they are, then rather than to think of psychotherapy-models as competing hypotheses of regular causal relationships, would it be better to think of them as compatible and/or overlapping attempts to put possible causal relations between dispositions of persons into words? If so, this remains to be expounded. Furthermore, one may wonder how we are able to do so (without stastistics). And how might this be psychotherapeutically helpful, if ever?
Causality, Complexity and Evidence in Health Sciences 
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