 After explaining that the meaning of a term depends on the theory to which it belongs, and that a consequence of theoretical advance is meaning change, Duhem continued: “If the theories admitted by this physicist are those we accept, and if we agree to follow the same rules in the interpretation of the same phenomena, we speak the same language and can understand each other. But that is not always the case. It is not so when we discuss the experiments of a physicist who does not belong to our school; and it is especially not so when we discuss the experiments of a physicist separated from us by fifty years, a century, or two centuries” (1954 [1906], 159). Duhem continued: “How many scientific discussions there are in which each of the contenders claims to have crushed his adversary under the overwhelming testimony of the facts! … How many propositions are regarded as monstrous errors in the writings of those who have preceded us! We should perhaps commemorate them as great truths if we really wished to enquire into the theories which gave their propositions their true meaning” (Duhem 1954 [1906], 160–161). These passages make the same basic points that both Feyerabend and Kuhn made with their claims about incommensurability of scientific theories: Because older ideas are misunderstood, as a result of taking them out of their theoretical context, proponents of incommensurable scientific theories misunderstand each other, both claiming to have the facts on their side. Kuhn and Feyerabend both claimed that in such a situation, even empirical arguments can become circular (Feyerabend 1965b, 152; Kuhn 1962, 94).