Shusuke Ioku
井奥 崇輔
Welcome to my website. I am a Ph.D. candidate in Political Science at the University of Rochester, specializing in historical political economy and conflict studies. My research examines state formation, state-building processes, and state repression through a combination of formal theory and micro-level historical data. I focus particularly on how patterns of popular resistance shape state development and how state repression strategies, in turn, influence forms of popular resistance.
Email: sioku[at]ur.rochester.edu
RESEARCH
Covert Subversion: Population Mobility and the Construction of the State in Early Modern Japan
Abstract. Throughout history, mobile subjects have constrained states’ extractive potential, yet this passive resistance has received far less systematic attention than direct resistance. I provide evidence that population mobility constrains states’ extractive capacity, even while undermining subjects’ ability to directly confront authority. I formally identify the conditions under which mobility constrains state taxation, and then test the model’s predictions by exploiting the unique context of Tokugawa Japan, where hundreds of local domains sharing basic institutional settings exhibited divergent tax rates. Leveraging original georeferenced data on peasant uprisings and domain taxation, I show that (i) villages farther from their home capital and closer to foreign capitals rebelled through exit rather than direct confrontation, and (ii) domains with more exit-prone villages imposed lower tax rates—a pattern persisting after accounting for various alternative mechanisms. As predicted by the model, this relationship is conditioned by neighboring domains’ labor-to-land ratios, which limited the feasibility of migration.
Thought-Based Targeted Repression: Theory and Evidence
Abstract. While scholars widely recognize targeted repression as an effective tool of autocratic control, I argue that such strategies can paradoxically undermine regime stability by inadvertently empowering the targeted faction, especially when that faction is defined by ideology rather than ethnicity or race. Although targeted repression fragments opposition movements, it enables leaders of the targeted faction to credibly signal their commitment to resistance, thereby garnering broader public support. I develop a formal theoretical model illustrating this mechanism and test its implications using the case of ideology-based repression in colonial Korea under Japanese rule. Following partial liberalization in the 1920s, Korean dissidents divided into communist and nationalist factions—a division the Japanese colonial government strategically exploited. Using a difference-in-differences (DiD) approach with novel individual-level data on dissident activities and punishments, I find evidence that (i) the government implemented biased judicial punishment against communists following the 1925 Public Order Preservation Act, which (ii) caused fragmentation between communist and nationalist factions, yet (iii) produced only limited suppressive effects on communist activities.
Nonstate Formation
Abstract. I analyze the formation of non-state polities at peripheries as a result of state formation. Intensive extraction efforts by the state compel subjects to flee toward peripheral regions beyond state control. Some elites capitalize on these displaced populations to build a centralized polity specialized in violence production. The resulting dynamic creates a self-enforcing regime with dual power structure, where both the central ruler and peripheral elites share common interests in extracting resources from sedentary populations, confining them within the territory and curbing irregular banditry. I illustrate this logic through the formation of military elites in early medieval Japan.
Hydraulic Civilizations
Abstract. Although agricultural surplus was vital for early state formation, it also exposed states to external threats. I claim that while surplus itself jeopardized states, the administrative capacity to generate it—specifically hydraulic management—promoted state persistence. Maintaining costly irrigation systems provided rulers with bargaining leverage over both external predators and internal subjects, deterred both invasions and defections, and thereby fostered stable territorial control. I illustrate this argument through a formal model and test it using global data of historical polities since 3400 BCE. Duration analysis shows that states with greater hydraulic dependence, measured by the potential yield gap between irrigated and rainfed farming, tended to endure longer without losing territories, while higher absolute yields accelerated territorial loss. The result was exclusively found in earlier periods, where developing hydraulic systems was more costly. Additionally, polities with greater hydraulic dependence tended to develop more complex social structures.
Military Innovation and Territorial State Formation
外交の計量分析：外交使節制度の衰微と再生
TALKS
- Weapons of the Weak
MPSA 2025; JSQPS 2024 Summer
- Teppo Made Japan
Waseda University, 2023
- Empirical Model of Alliance Formation
Waseda University, 2022
- Threats and Assurances in Crisis Bargaining
MPSA 2021
AWARDS & GRANTS
- Best Paper/Presentation Award
2024, Graduate Seminar, Department of Political Science, University of Rochester
- Best Graduation Thesis Award
2021, Waseda University
TEACHING
- TA for ECO 288, Game Theory
2025 Spring, Prof. Tasos Kalandrakis, University of Rochester
2024 Spring, Prof. Romans Pancs, University of Rochester - TA for ECO 255, Poverty and Development
2024 Fall, Prof. Anderson Frey, University of Rochester
- TA for PSCI 407, Mathematical Modeling
2023 Fall, Prof. John Duggan, University of Rochester
A core method course in the Political Science Ph.D. program - TA for 国際政治学
2021 Spring, Prof. Shuhei Kurizaki, Waseda University
EDUCATION
- University of Rochester (Aug 2021 - Present)
Ph.D. in Political Science
Major: Formal Theory, International Relations
Advisors: Scott F. Abramson, Hein Goemans, Casey Petroff, Sergio Montero - Waseda University (Apr 2020 - Aug 2021)
M.A. in Political Science
Advisors: Shuhei Kurizaki, Atsushi Tago - University of Tokyo (Apr 2011 - Aug 2017)
M.P.P / B.A. in Philosophy