Qualitative research is just as able as quantitative research to follow certain fundamental principles of logic in general and scientific reasoning in particular. Two such principles are the logic of modus ponens and the logic of modus tollens. In this essay, we frame different research approaches—positivist research, interpretive research, action research, and design research—in the forms of modus ponens and modus tollens. Three issues emerge from this framing and call into question how research is now conducted in the discipline of information systems. They are the issue of a common scientific basis, the issue of the fallacy of affirming the consequent, and the issue of summative validity. Both rigor and relevance in information systems research may be better achieved by attending to the three issues.