From malfunction to mechanism

Malfunctions, deficits, and errors provide considerable insight into key features of the entities in which they occur. In particular, the careful analysis of patterns of functioning and malfunctioning facilitate discovery, explanation and theorizing about structure, function, and underlying mechanisms of a system. In some cases, malfunctions even supply the unique probe into the internal workings of a system. This essay analyzes methods used by various disciplines involving malfunctions such as mutations, visual illusions, action slips, or speech errors, and identifies common patterns of malfunction-based research strategies that contribute to the decomposition of systems, the tracing of sequences of events, the localization of subsystems, and the generation and testing of complex mechanistic hypotheses.