The Deductive-Nomological Model and the Limits of Scientific Explanation

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Explanation is one of the highest functions of scientific knowledge. To describe a phenomenon is to record it; to explain it is to understand it, to relate it to general principles that clarify its cause or reason. Since the origins of modern science, the question of what it means to “explain” has accompanied the very idea of knowledge. The positivist tradition sought to define explanation as a logical process in which a particular phenomenon can be deduced from general laws and initial conditions. If I know that all metals expand when heated and that iron is a metal, I can deduce that iron will expand when heated. Explanation thus becomes a form of rational deduction, the application of general rules to specific cases. This conception is immediately attractive: it offers a rigorous and orderly image of science, in which every phenomenon fits within a network of universal laws. Yet precisely this logical elegance has raised profound questions about its adequacy in capturing the complexity of actual scientific practice and the diversity of ways in which scientists make sense of the world.