Replication Data for: Party system types and the decline of systemness in Western Europe: are party system classifications still useful?

Party system classifications have been central in political science, especially until Sartori’s influential typology in 1976. However, recent years have seen diminished attention to such classifications. Western European party systems have significantly transformed, particularly over the last 15 years due to multiple crises, affecting their core structure, or what Sartori termed ‘patterns of interparty competition’. This raises questions about whether these changes have undermined the very concept of systemness, making classifications irrelevant. This research note redefines party systems based on the number and composition of relevant political poles (governing alternatives) and, through a long-term analysis of Western Europe (20 countries since 1945), assesses their degree of systemness. Results indicate that many systems have become ‘non-systems,’ with fluctuating and unstable party poles. Most Western European systems have exhibited this ‘non-system’ type for at least half of legislatures since 1989, thus making classifications only short-lived snapshots and inevitably useless for long-term accounts.政党体系分类始终是政治学研究的核心议题，在1976年萨托里（Sartori）发表极具影响力的类型学研究之前，这类分类的核心地位尤为凸显。然而近年来，学界对这类分类的关注度已大幅下滑。西欧政党体系已发生显著变革，尤其是在过去15年间，多重危机冲击了其核心结构——即萨托里所称的「政党间竞争模式（patterns of interparty competition）」。这不禁引发疑问：这类变革是否已侵蚀了政党体系的「体系性（systemness）」核心内涵，使得此类分类研究失去意义？本研究简报基于相关政治阵营（political poles，执政备选主体）的数量与构成，重新定义了政党体系；并通过对1945年以来西欧20个国家的长期分析，评估了各体系的体系性程度。研究结果显示，诸多政党体系已演变为「非体系」，其政党阵营处于波动且不稳定的状态。自1989年以来，多数西欧政党体系在至少半数的议会任期内都呈现出「非体系」特征，这意味着此类分类仅能作为短暂的快照式记录，无法用于长期的研究阐释。