Shusuke Ioku
井奥 崇輔
Thank you for visiting 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 authoritarian politics through a combination of formal theoretical models and analysis of fine-grained historical data.
Email: sioku[at]ur.rochester.edu
RESEARCH
Weapons of the Weak
Abstract. Throughout history, mobile subjects have constrained states’ extractive potential, yet this passive resistance technique has received far less systematic attention than direct collective confrontation. In this paper, I (i) formally identify the conditions under which population mobility restrains state taxation, and (ii) provide empirical evidence for this relationship using the ideal historical context of Tokugawa Japan, a setting with nearly 300 autonomous domains that shared basic institutional features but exhibited remarkably divergent tax rates (20-70%). Leveraging newly digitized data on domain capitals, 40,086 villages, and records of peasant revolts, I show that (i) peripheral villages (those farther from their home capital and closer to foreign capitals) are more likely to resist through exit rather than collective confrontation, and (ii) domains with more peripheral village distributions imposed lower tax rates, a pattern that persists after accounting for various alternative mechanisms. The mobility-taxation link, as theoretically predicted, is attenuated by high labor-to-land ratios in neighboring domains.
Counterfeit Liberty
Abstract. Autocrats can strategically expand freedom to gain intelligence about dissident organizations (e.g., identifying leaders), thereby improving the efficiency of future repression. I formalize this logic through a dynamic model of autocratic repression and illustrate it using the case of Korea under Japanese rule (1910-1945). Drawing on original data from biographies of over 18,000 independence activists and their criminal court records, I demonstrate that following a sharp rise in public grievances, the government initially softened punishment for organizational activities—encouraging the growth of dissident organizations—before subsequently intensifying repression against these same activities, effectively suppressing dissent through this strategic sequence.
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
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