Boolean comparative analysis of qualitative data

This paper explores the use of Boolean logic in the analysis of qualitative data, especially on the basis of so-called process theories. Process theories treat independent variables as necessary conditions which are binary rather than variable in nature, while the dependent variable is a final cause. In this respect, Boolean comparison appears to be a rigorous method for testing process theories on the basis of qualitative evidence, for example, from case studies. It is argued that Boolean logic may compensate for some of the weaknesses of the conventional approach to process studies — going back to Stuart Mill's (1843) system of logic — by systematically comparing observations without forsaking complexity too much. In addition, Boolean logic systematically structures the kind of interpretive dialogue between theory and evidence typically found in qualitative research. Finally, a procedure for using Boolean analysis is outlined. This procedure involves systematic attempts to falsify and identify hypotheses on the basis of truth tables constructed from qualitative data.