A major contention of Rick Altman's sweeping study Film/Genre (1999) is that traditional genre criticism all too routinely assumes generic fixity at the expense of generic historicity. “Genre films” are often considered to have fixed narrative patterns and to repeat a relatively unchanging set of codes. Moreover, genre films are thought to be derivative, commercial in both aim and scope, and as a consequence not art. Fritz Lang's Rancho Notorious (1952), to take one example, may be read as a “classic” Western in this regard, exhibiting clear-cut and enduring conventions: the mythical settings on the nineteenth-century American frontier, the encounter between law and lawlessness, and the use of stock characters such as cowboys, outlaws, and “noble” Native Americans. While traditional genre criticism has deemed such elements to be timeless and transhistorical, Altman notes that this use of genres overlooks the historical ebb and flow that consolidates not only specific genres but also the concept of genre itself. “Stressing the apparently representative straight stretches of the mighty genre river rather than its tortuous tributaries, its riverbed-defying floods, or its tidewater-dominated estuary, recent genre theory has devoted too little attention to the logic and mechanisms whereby genres become recognizable as such.” Traditional genre criticism has not drawn sufficient attention to the varied contestations and negotiations that consolidate genre categorization. Challenging the notion that genre categories exist outside the flow of time, Altman argues that the categories themselves, in close conjunction with the generic cues through which they are constituted, are always already embedded in a historical trajectory, a “mighty genre river,” and are thus always in flux.