单选题 .  ①Historian E.H Carr's thesis that all debates concerning the explanation of historical phenomena revolve around "the question of the priority of causes" is so familiar to historians as to constitute orthodoxy within their profession. ②The "true historian", as Carr puts it, will feel a professional obligation to place the multiple causes of a historical event in a hierarchy by means of which the primary or ultimate cause of the event can be identified. ③In the Marxist mode of historical explanation (historical materialism), a universal hierarchy of causes is posited in which economic factors are always primary. ④In the classic, more widely accepted alternative ultimately derived from Weberian sociology, hierarchies of causes are treated as historically specific: explanatory primacy in any particular historical situation must be established by empirical investigation of that situation, not by applying a universal model of historical causation.
    ①While the need to rank historical causes in some order of importance may seem obvious to most historians, such hierarchies raise serious philosophical difficulties. ②If any historical event is the product of a number of factors, then each of these factors is indispensable to the occurrence of the event. ③But how can one cause be "more indispensable" than another? ④And if it cannot, how can there be a hierarchy of indispensable causes? ⑤It was this problem that first led Weber himself to argue for the impossibility of any general formula specifying the relative importance of causes; we cannot, for example, conclude that in every capitalist society religious change has been more significant than economic change (or vice versa) in explaining the rise of capitalism.
    ①Runciman offers a different argument leading to the same conclusion. ②He points out that it is possible to identify specific factors as the primary causes of a particular historical event only relative to an initial set of background conditions. ③For instance, if we accept English defeats after 1369 in the Hundred Years War as a given, then we may identify the high levels of taxation necessitated by these military reverses as the "main" cause of the Peasants Revolt of 1381. ④If instead we regard the financing of warfare by taxation in this period as a background condition, then we will see the English reverses themselves as the main cause of the revolt. ⑤However, neither ordinary life nor historical practice offer reliable criteria by which to distinguish causes from background conditions and thus to resolve historical debates about the relative importance of causes. ⑥And this difficulty casts doubt not only on the Marxist effort to identify a universal hierarchy of causes, but also on any attempt to identify an objective hierarchy of causes—even of the historically specific kind favored by non-Marxists.27.  The primary purpose of the passage is to ______