Research

"I must study politics and war, that our sons may have liberty to study mathematics and philosophy. Our sons ought to study mathematics and philosophy, geography, natural history and naval architecture, navigation, commerce and agriculture in order to give their children a right to study painting, poetry, music, architecture, statuary, tapestry and porcelain."

                                                                                       - John Adams

Publications

Highlighting the strength of ‘partyism’ in many democracies, recent scholarship pays keen attention to increasing hostility and distrust among citizens across party lines, known as affective polarization. By combining a conjoint analysis with decision-making games such as dictator and trust games, we design a novel survey experiment to systematically estimate and compare the strength of the partisan divide relative to other social divides across 25 European democracies. This design also allows us to investigate how the two components of affective polarization, in-group favoritism and out-group derogation, are moderated by the way parties interact with each other. We first find dominance of the partisan divide compared to other social divides that constitute traditional cleavages such as social class and religion. Second, we show that affective polarization in Europe is not primarily driven by out-group animus. Finally, we demonstrate that coalition partnership lessens affective polarization by reducing both in-group and out-group biases.

As European integration has become politicized over the last several decades, scholars have paid keen attention to the role of identity in shaping political conflicts and contestation in Europe. We investigate the microfoundation of the political divide over European integration by building on and extending theories of social identity and recent studies on affective polarization. We design a survey experiment that allows us to explore the extent of divides over European integration. We find a statistically significant and substantively large magnitude of the divide based on European identity. Our results also show that this divide over European integration deserves particular attention as it is largely driven by out-group animosity, rather than in-group favoritism. Lastly, we show that electoral context, such as electoral salience, involvement in election, elite polarization, and the strength of Eurosceptic parties, influences the intensity of the European divide.

In the face of the discourse about the democratic deficit and declining public support for the European Union (EU), institutionalist scholars have examined the roles of institutions in EU decision making and in particular the implications of the empowered European Parliament. Almost in isolation from this literature, prior research on public attitudes toward the EU has largely adopted utilitarian, identity and informational accounts that focus on individual-level attributes. By combining the insights from the institutional and behavioral literature, this article reports on a novel cross-national conjoint experiment designed to investigate multidimensionality of public attitudes by taking into account the specific roles of institutions and distinct stages in EU decision making. Analyzing data from a large-scale experimental survey in 13 EU member states, the findings demonstrate how and to what extent the institutional design of EU decision making shapes public support. In particular, the study finds a general pattern of public consensus about preferred institutional reform regarding powers of proposal, adoption and voting among European citizens in different countries, but notable dissent about sanctioning powers. The results show that utilitarian and partisan considerations matter primarily for sanctioning dimension.

What type of trade agreement is the public willing to accept? Instead of focusing on individual concerns about market access and trade barriers, we argue that specific treaty design and, in particular, the characteristics of the dispute settlement mechanism, play a critical role in shaping public support for trade agreements. To examine this theoretical expectation, we conduct a conjoint experiment that varies diverse treaty-design elements and estimate preferences over multiple dimensions of the Transatlantic Trade and Investment Partnership (TTIP) based on a nationally representative sample in Germany. We find that compared to other alternatives, private arbitration, known as investor-state dispute settlement (ISDS), generates strong opposition to the trade agreement. As the single most important factor, this effect of dispute settlement characteristic is strikingly large and consistent across individuals’ key attributes, including skill levels, information, and national sentiment, among others.

At the beginning of 2012, the 17 countries of the eurozone and eight of the ten remaining countries of the EU reached an agreement on the Treaty on Stability, Co-ordination, and Governance in the Economic and Monetary Union (TSCG, known as the Fiscal Compact). The article traces six successive drafts of the agreement to discover how these countries reached agreement. We argue that there are three different procedures that can lead different actors with veto power over an agreement to suspend their veto – they increase, decrease or preserve the dimensionality of the underlying space. We call the three methods compensation, elimination and compromise respectively, and discover that in the Fiscal Compact the agreement was achieved mainly through elimination.

Dissertation

“The Partisan Secret: Institutional Constraints on Policy Change and Partisanship.”

Committee: Robert J. Franzese, Jr. (co-chair), Ted Brader (co-chair), George Tsebelis, Phoebe C. Ellsworth (Psychology)

Manuscripts under Review

Hahm, Hyeonho, and Michael Zilis. “A Countermajoritarian Institution in the Public Mind: Judicial Legitimacy of the Federal Constitutional Court in Germany.” Under Review

Hahm, Hyeonho. “Partisans in Institutional Context: Institutional Constraints on Policy Change and Mass Partisanship.” Revise and Resubmit, British Journal of Political Science

Hahm, Hyeonho, and Michael Zilis. “The Supreme Court at the Bar of Politics: An Interbranch Perspective on Judicial Legitimacy.” Under Review

Hahm, Hyeonho. “The Partisan Secret: Institutional Constraints on Policy Change and Party Unity.” Under Review

Manuscripts in Preparation

Hahm, Hyeonho. “Political Costs of Noncompliance: An Experimental Analysis of EU Implementation.” Working Paper

Hahm, Hyeonho, Thomas König and David Hilpert. “Populism Against the Europe: Estimating Populists’ Multidimensional Policy Preferences.” Working Paper

Hahm, Hyeonho and David Hilpert. “Partisan Love and Hate After the European Parliament Elections” Working Paper

Hahm, Hyeonho, Thomas König and David Hilpert. "Judicial Legitimacy of the Court of Justice of the EU: an Engine of European Integration or a Countermajoritarian Institution?” Working Paper