While multi-method research is experiencing a surge of popularity, there are reasons to worry about whether multi-method applications are producing more grounded, justified, and persuasive inferences than single-method studies. These concerns arise from the 'triangulation' framework as prototypical research design for multi-method social science. Simply put, triangulation designs involve asking the same causal inference question using two different methods, checking same substantive conclusions. The metaphor is to the geometric technique of estimating distance by measuring the angle of sight toward an object from two different vantage points.

Triangulation in social sciences has major flaws. One is well-known and widely discussed: what conclusion should be drawn when the two methods produce different findings? Unfortunately, the list of intellectually plausible responses to such an outcome is all but unbounded.