Plausibility and Early Theory in Linguistics and Cognitive Science

Various notions of plausibility are used in cognitive science to argue for or against the "goodness of theories." However, plausibility remains poorly understood and difficult to analyze. We review debates in the philosophy of science on uses of plausibility in the assessment of novel scientific theories as well as recent attempts to formalize, reform, or eliminate specific notions of plausibility. Although these discussions highlight important concerns behind plausibility claims, they fail to identify viable notions of plausibility that are sufficiently different from other criteria of "good theory," such as prior probability or external coherence. We survey uses of plausibility in linguistics and cognitive science, confirming that plausibility is often a proxy for other criteria of good theory. We argue that the need remains for concepts of plausibility that can be employed to assess the quality of proposals at the early stages of theory development when other criteria are not yet applicable. We identify two such notions: one relating to formal constraints on theories and another capturing initial epistemic consensus, if not necessarily convergence on the truth, about the target system in a community of inquiry. We briefly assess the specificity and added value of these notions of plausibility relative to other criteria for good theory.