UNDERDETERMINATION AND INCOMMENSURABILITY IN CONTEMPORARY EPIDEMIOLOGY

In the shadowy world between philosophy of science and ethics lie the paired concepts of underdetermination and incommensurability. Typicall y scientific evidence underdetermines the hypotheses tested in researc h studies, providing neither proof nor disproof. As a result, scientis ts must judge the weight of the evidence, and in doing so, bring scien tific and extrascientific values to bear in their approaches to assess ing and interpreting the evidence. When different scientists employ ve ry different values, their views are said to be incommensurable. Less prominent differences represent partial incommensurabilities. The defi nitions and analyses provided by McMullin and by Veatch and Stempsey l ay the foundation for the description of partial incommensurabilities in the current practice of assessing and interpreting epidemiologic ev idence. This practice is called ''causal inference'' and is undertaken for the purpose of making causal conclusions and public health recomm endations from population-based studies of exposures and diseases. Fol lowing the work of Bayley and Longino, several suggestions are examine d for dealing with the partial incommensurabilities found in the gener al practice of causal inference in contemporary epidemiology. Two spec ific examples illustrate these ideas: studies on the relationship betw een induced abortion and breast cancer and those on the relationship b etween moderate alcohol consumption and breast cancer.