 In the history of theorizing about explanation, Skow argues, the higher and lower levels of reasons-why have been conflated as far back as the Deductive-Nomological theory of Hempel and Oppenheim (1948). According to the D-N model, an answer to the question of why an event occurred must cite both prior conditions and a law of nature, and the occurrence of the explanandum event must be deducible from the latter jointly. For example, certain physical laws are involved in the lighting of a match when it is struck. According to the D-N model, but not according to the account of reasons-why in Skow 2016, those laws are part of the explanation of why the match lit.