Shusuke Ioku

井奥 崇輔

CV RESEARCH CONTACT

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 explores state formation, state-building processes, and state repression through the integration of formal theory with micro-level geographic and personal data. My current research topics range from the mechanisms of state subversion from both below and above to the strategic interplay between state repression and dissident responses.

Email: sioku[at]ur.rochester.edu

RESEARCH

Exit: Mobility and State Extraction in Early Modern Japan

Under Review DOWNLOAD

Abstract. Throughout history, subjects have exploited their mobility across jurisdictions to constrain rulers’ extractive capacity. I develop a formal model specifying the conditions under which mobility, while weakening subjects’ ability to directly confront authority, nonetheless constrains taxation. I test the model’s implications in Tokugawa Japan’s context using original geo-referenced data on domains, villages, and peasant resistance. A novel measure of village mobility—based on the relative distance between home and foreign capitals—captures exposure to alternative authorities. The analysis shows that (i) villages more exposed to foreign authority favored exit over confrontation; (ii) domains facing higher mobility imposed lower taxes, a finding robust to alternative mechanisms; (iii) this constraining effect weakened where neighboring domains had saturated labor markets; and (iv) distance to borders is a weaker predictor than capital-based exposure, underscoring that access to alternative authority, rather than simple proximity to foreign territory, enabled mobility to function as a constraint on state extraction.

Self-State Subversion: The Birth of Feudalism in Early Medieval Japan

Work In Progress

Abstract. While scholars broadly agree that feudal orders arose from the limitations of centralized state control, much less is known about the mechanisms through which this process began and unfolded—specifically, who fostered the fragmentation of state power and where it originated. I propose a theoretical framework identifying the conditions under which statebuilders deliberately hollow out their own administrative apparatus by privatizing extraction: granting fiscal immunities in exchange for a share of the returns. I evaluate the model’s implications using the case of early medieval Japan, where varying degrees of feudalization across regions can be systematically observed through estate commendations to the imperial court. Consistent with the theory, I find that estate commendation by emerging local warrior elites occurred most prominently in peripheral regions where central authority was weak but local administrative capacity remained strong.

Thought Police: Theory and Evidence of Ideological Repression

Work In Progress

Abstract. Autocratic regimes frequently employ repression to target specific groups of citizens. This paper examines state repression directed at particular ideologies—a form of control that creates unique enforcement challenges. Since individuals’ ideological commitments are unobservable to authorities, thought repression generates a fundamental information problem compounded by pooling incentives among dissidents. Under this endogenously reinforced information asymmetry, optimal state repression exhibits a tendency toward increasing indiscrimination. I develop this theoretical logic through a formal model of ideological oppression and provide empirical support using evidence from communist repression by Japan’s special higher police between 1911 and 1945. Employing an event-study design with original individual-level data on 16,811 activists, I demonstrate two concurrent trends: over time, dissidents both with and without radical ideologies became equally likely to engage in organizational activities, while the government’s repression strategy became increasingly indiscriminate on both low- and high-profile citizens.

Hydraulic Civilizations

Work In Progress

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

Coauthored with Scott Abramson, Sergio Montero, and Michael Gibilisco

Work In Progress

Abstract. Social scientists have argued that conflict and military technological innovation fostered the formation of territorial states. While the literature has predominantly examined European history, Japan’s Warring-States Period offers a unique context to test this claim; the island country initially composed by more than 100 autonomous local powerholders (daimyo) was exposed to an exogenous shock of military innovation, an accidental importation of firearms in 1543, after which the fragmented society rapidly transformed into a centralized state under a singular authority. Using original grid-year datasets of battles, castles, and territorial changes, we show (preliminary, descriptive) results suggesting that the technological shock diminished defensive advantage and made economic power better translate into battleground success, thereby inducing small rulers to concede their autonomy.

外交の計量分析：外交使節制度の衰微と再生

Coauthored with Shuhei Kurizaki and Rui Asano
A book chapter in 『国際関係研究の方法』（東京大学出版会）

Published in 2021

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, Casey Petroff, Hein Goemans, 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)

  B.A. in Philosophy + M.P.P