The Weaknesses of Strong Inference

Platt’s 1964 paper “Strong Inference” (SI), published in Science, has had considerable influence upon the conception of the nature of the scientific method held in both the social and physical sciences. Platt suggests that a four-step method of specifying hypotheses and conducting critical experiments that systematically eliminate alternatives has been responsible for progress in the history of the successful sciences and, if adopted, will allow the less successful sciences to make greater progress. This paper criticizes SI on a number of grounds including: 1) no demonstration of the central historical claim, that is, that the more successful sciences actually have utilized this method more frequently than the less successful sciences; 2) poor historiography, in that more faithful explications of some of the historical case studies Platt cites as canonical examples of SI fail to support that SI was actually used in any of these cases; 3) failure to identify other cases of important scientific progress that did not use SI and instead used distinct scientific methods; 4) neglect of the importance and implications of background knowledge used in problem formulation; 5) the impossibility of enumerating a complete set of alternative hypotheses; 6) no acknowledgement of the Quine-Duhem thesis indicating that “critical” experiments are actually logically inconclusive; 7) the assumption that there is one scientific method; and 8) significant ambiguity regarding exactly how each of the four steps of SI is to be faithfully implemented. Some recommendations regarding a normative scientific method are given.