Since the late 1960s, the Iranian-American artist Siah Armajani has primarily worked on the border between sculpture and architecture, creating large-scale public installations such as reading rooms, gardens and bridges. These works commonly evidence a formal concern with relationships between part and whole. This article connects Armajani’s interest in part–whole relations with the writings of Robert Venturi, arguing that Armajani’s practice establishes a critical dialogue with the history of modernist architecture. However, it also demonstrates that Armajani’s practice complicates the proto-postmodern approach of Venturi’s Complexity and Contradiction in Architecture (1966) in several ways. Unlike Venturi, Armajani explicitly politicizes the question of part–whole relations, presenting it not as a purely aesthetic question, but as a formal metaphor for egalitarian social relations. By incorporating certain distinctly modernist techniques into his sculptures, Armajani also shows that, contra Venturi, the question of how to safeguard diversity within a social collective was already a concern among modernists themselves. Finally, Armajani's work further contrasts with Venturi’s writing through its turn to the politics of class struggle. Drawing on the writings of the Marxist theorist Ellen Meiksins Wood, the article argues that Armajani drew attention to the limitations inherent in postmodernism’s ‘politics of diversity’, demonstrating its class blindness and thus its failure to sufficiently challenge contemporary capitalist ideologies.