This thesis is inspired by an ending—that of a cowboy hero riding away, back turned, into the setting sun. That image, possibly the most evocative and most repeated in the Western, signifies both continuing adventure and ever westward motion as well as a restless lack of final resolution. This thesis examines the ambiguous endings and the conditions leading up to them in two film Westerns of the 1950s, George Steven's Shane (1953) and John Ford's The Searchers (1956). Fascinatingly, the tension and uncertainty conveyed throughout these films is also characteristic of life in modernity, a connection which has previously gone overlooked. In my analysis, I study the ties between the postwar film Western and the philosophy of modernity to interpret these works in a new light, illuminating their generic context and their understudied philosophic dimensions. This reading highlights these films' continued relevance, showing how they have enabled creators and audiences to reflect on experiences of modernity in the idiom of the celluloid century.