This study examines specialization in Dutch Lower House debates between 1945 and 1994. We study how specialization translates in the phenomenon of ``epistemic capture'' in democratic politics. We combine topic modeling, network analysis and community detection to complement lexical ``distant reading'' approaches the history of political ideas with a network-based analysis that illuminates political-intellectual processes. We demonstrate how the breadth of political debate declines as its specialist depth increases. To study this transformation, we take a multi-level approach. At the (institutional) macro-level, network modularity shows an increase in the modularity of topic linkage networks, indicating growing specialization post-1960, linked to institutional reforms. At the (political) meso-level, we similarly observe specialization in node neighborhood stability, but also variation as the consequence of ideological and party political change. Lastly, micro-level analysis reveals persistent thematic communities tied to increasingly stable groups of individuals, revealing how policy domains and politicians are captured in ossified specialisms. As such, this study provides new insights into the development of twentieth-century political debate and emergent tensions between pluralism and specialism.