AI 中文总结
该研究提出基于智能体的模型，对比四种民主制度，发现分裂议会的法案通过率骤降源于反对派凝聚阻挠，禁用纪律可恢复通过率，且四种制度中通过率与代表权呈单一权衡谱系。
AI 中文摘要
议会制在基准情形下通过的法案比总统制更多，但在政党体系分裂时法案通过率会骤降至接近零。现有文献提出了三种相互竞争的微观解释：联盟组建失败、政党纪律以及委员会守门机制。这些机制在任何真实立法机构中同时发挥作用，因此观察性研究难以区分它们的贡献。我们提出了一个基于智能体的模型，用于比较四种民主制度：纯议会制、纯共和制/总统制、总理-总统制（法国）以及总统-议会制（俄罗斯）。在四个场景及每个单元N=200个随机种子的设置下，我们报告了自助法置信区间、莫里斯筛选、索伯尔方差分解、机制消融实验以及悬峙议会变体的对比。研究得出三项发现：其一，仅政府组建失败并不会停止立法：当分裂的议会回归个人投票时，议会通过率（46.4%）与总统制基准（44.8%）在统计上无差异；法案通过率降至0.05%需依靠凝聚的反对派阻挠。其二，禁用纪律可使分裂情形下的法案通过率恢复至46.7%，且恢复幅度在四种制度中呈单调变化，该模式在改变共同纪律水平时依然成立。其三，通过率与代表权之间的权衡是单一谱系：议会制以代表保真度为代价最大化产出；共和制通过总统否决最大化保真度；半总统制变体则介于两者之间。
英文摘要
Parliamentary systems pass more bills than presidential systems at baseline, but collapse to near-zero passage under party-system fragmentation. The literature offers three competing micro-explanations: coalition-formation failure, party discipline, and committee gatekeeping. These operate simultaneously in any real legislature, so observational studies struggle to separate their contributions. We present an agent-based model that compares four democratic institutions: pure parliamentary, pure republican/presidential, premier-presidential (France), and president-parliamentary (Russia). Across four scenarios and N=200 seeds per cell we report bootstrap confidence intervals, Morris screening, Sobol variance decomposition, mechanism ablations, and a hung-parliament variant comparison. Three findings emerge. First, government formation failure alone does not halt legislation: when a fragmented parliament reverts to personal voting, parliamentary passage (46.4%) is statistically indistinguishable from the presidential benchmark (44.8%); collapse requires cohesive opposition obstruction, which drives passage to 0.05%. Second, disabling discipline restores fragmented passage to 46.7%, and the rescue magnitude is monotone across the four institutions in a pattern that survives varying the common discipline level. Third, the passage-representation tradeoff is a single spectrum: parliamentary maximises throughput at the cost of representational fidelity; republican maximises fidelity via the presidential veto; semi-presidential variants split the difference.
CommentsCode, data, and interactive demo: https://github.com/tofuadmiral/institutional-representation-abm
