Research Statement
My research advances the field’s understanding of how humanitarian and liberal democratic institutions, norms, and social identity influence the domestic politics of war and conflict. In my scholarship, I am particularly focused on producing new knowledge about the impact of individuals, including everyday citizens, elites, and policymakers. My approach contrasts with studies that emphasize the international system, nation-states, and other macro-level factors. Due to my interest in individuals and their political opinions, I frequently employ surveys and experimental survey methodologies. However, my major projects also incorporate other data sources and methods, such as qualitative case studies and macro-level statistical analysis.
Below, I elaborate on my research regarding (1) humanitarianism in the laws of war, (2) the social consequences of liberal democracy in world politics, and (3) democratic values in comparative politics. For each section, I provide a descriptive narrative of my scholarship and explain its significance to social scientific knowledge.
Narrative #1: Can international law humanize people’s opinions about war?
One of human society’s significant achievements in the 20th century was embedding humanitarian principles into nearly universally accepted international laws of war, such as the Geneva Conventions. Optimists argue that this legalization encourages people worldwide to embrace deeper moral commitments to reducing human suffering resulting from war and wartime conduct. This accomplishment should be celebrated, but my research raises new concerns: these laws and institutions interact with human psychology, norms, and identity in ways that limit the impact of international law on society.
To begin, international humanitarian law unconditionally bans certain types of wartime conduct, such as the abuse of prisoners of war. Chu (2019), however, demonstrates that people’s deeply held commitments to reciprocity persist: they largely support reciprocal wartime abuses and are only willing to adhere to international law if other countries commit to doing the same. Thus, in this case, international law can stabilize mutual good behavior, but once one side breaks the rules, the law will struggle to prevent the other side from also breaking the rules.
Relatedly, international law bans all wars except those fought in self-defense or those authorized by the United Nations Security Council. However, according to Chu (2025), international public opinion on war still aligns with a moral and social-psychological logic: people approve of illegal wars that pursue humanitarian aims (i.e., military humanitarian intervention). Furthermore, when assessing the legitimacy of humanitarian wars, people often prioritize fitting in with their social peers over adhering to the rules of universal and legal institutions like the United Nations Security Council.
Second, international norms broadly dictate that we must evaluate people’s intentions to assess the legality of their wartime actions. For instance, the law differentiates between intentionally and accidentally bombing a civilian building. However, people’s psychological predispositions lead them to first respond to the moral harm caused by an action and then infer intentions: if an action causes harm, they tend to assume it was done intentionally. When something bad occurs, people are biased to assume it is a purposeful conspiracy (Chu, Holmes, and Traven 2020; Traven, Holmes, and Chu 2023).
Third, people’s attitudes toward war are significantly shaped by their social identity. For example, according to various international norms and legal doctrine, humanitarian action should, in theory, be taken to save innocent civilians without discrimination. However, in practice, people are more likely to support actions to save people they identify with, particularly along religious lines (Chu and Lee 2024). Similarly, even policymakers express identity biases in their openness to refugees, which should instead be received based on humanitarian standards (Shaffer, Pinson, Chu, and Simmons 2020). People’s attitudes toward post-war reconciliation, such as having their government apologize for war crimes, are also heavily influenced by their nationalistic sentiment or identity-based attachments to their country (Kitagawa and Chu 2021).
Thus, my research ultimately demonstrates that international law shapes society’s understanding of warfare, but people’s preexisting norms, identities, and psychological biases significantly limit the contexts in which it can exert such influence.
Scientific contributions. A fundamental question in the social sciences is whether laws and institutions can shape human behavior, including people’s opinions and moral beliefs. In international relations scholarship, the debate often revolves around optimists who believe that international institutions influence domestic norms and state behavior, versus pessimists who argue that they are primarily ineffective. My research intervenes in this debate with theory and evidence, generally siding with the pessimists. Existing literature reaches its pessimistic conclusions mainly by pointing to macro-level phenomena, such as the observation that countries tend to sign international treaties only when they align with their convenience or self-interest. In contrast, my work demonstrates the micro-level processes through which international law may be limited in its influence, providing new insight into the relationship between rules, institutions, and human values and behavior.
Beyond making theoretical and substantive contributions, my scholarship also advances applied survey methodology in studying the laws of war. Chu (2019), for example, shows how the field’s previous use of “no-information” control groups in survey experiments led to incorrect conclusions about whether reciprocity affects public opinion on war. To provide another example, Blair, Chu, and Schwartz (2022)’s novel application of the list experiment, a survey technique used to reveal people’s hidden beliefs, has helped the field more accurately document people’s true attitudes toward the use of chemical and nuclear weapons during war.
Narrative #2: What are the social consequences of liberal democracy on world politics?
Democracy, especially liberal democracy, creates social divisions in international relations. Liberal democratic countries tend to form an exclusive club or ingroup, and their citizens express this worldview. The social cohesion among democracies enables their leaders to maintain greater domestic support for military alliances by invoking shared values in public rhetoric and diplomacy (Chu, Ko, and Liu 2021). The ideational affinity among democracies also explains why organizations representing the liberal community, like NATO, can exert political legitimacy and influence on citizens and policymakers within its social borders (Chu 2025).
This democratic social identity is not only about building ingroup cohesion; it also creates friction with outgroups. Citizens of liberal democracies, for example, view nondemocratic powers as greater threats to the international system, even after accounting for traditional economic and security factors (Chu 2021). Similarly, policymakers in liberal democracies tend to discriminate against economic investments from autocratic countries, particularly in the context of U.S.-China rivalry (Chen and Chu w.p.). Significantly, political regime and ideology seem to influence these preferences more than factors like race (Chu 2025; Chen and Chu w.p.).
Thus, the social divide between democracies and non-democracies shapes how elites and citizens perceive international relations, leading to significant consequences. The influence of elites is crucial because they formulate policy. Additionally, public opinion is important as it affects policymaking, especially in democratic countries (Chu and Recchia 2022).
Scientific contributions. My work advances international relations theory concerning the link between social identity and (democratic) political regimes, as well as the political consequences of this link on substantive issues like military intervention, alliances, and great power politics. Social identity theory (SIT), initially developed in social psychology, has been widely applied to explain political phenomena. Earlier IR applications of SIT draw from the social constructivist paradigm and focus on macro-level dynamics (e.g., explaining how countries hold identities); however, there have also been breakthroughs in micro-level research.
My work makes fundamental contributions to understanding the impact of liberal democracy on the international system, largely by applying and developing SIT. For example, my book on social cues innovates within SIT to address the following question: why can some international institutions “legitimize” a country’s foreign policy, increasing domestic and foreign approval for that policy? I reframed legitimization as a form of identity politics, where group members sharing a common identity (ingroup members) can influence each other. The book further clarifies the causal process to explain how social cuing works and theorizes why specific institutions can facilitate social cuing among certain audiences (e.g., how NATO mobilizes support among liberal democracies). My theory challenges the dominant explanations in the field, which focus on legitimization from legal, material, and rational-informational perspectives. In conjunction with the extensive empirical work in this book, my research thus develops foundational theory about social identity in politics, while also providing a new answer to an enduring question in the field of IR regarding international institutions and their political legitimacy.
My other research further demonstrates how democratic social identity and values influence China’s global soft power (Chu 2021) and the political rhetoric of military alliances (Chu, Ko, and Liu 2021). I have also applied SIT to explain how racial and religious identities might affect Americans’ support for humanitarian intervention in other countries (Chu and Lee 2024). Collectively, these articles make significant theoretical contributions to understanding how identity, norms, and values operate in international relations, as well as substantive contributions to the understanding of consequential phenomena, such as the nature and determinants of China’s soft power.
Narrative #3: How do people from different societies think about democracy?
Over the last century, most of the world has increasingly embraced liberal democracy, particularly electoral democracy, as a way to organize political society. The number of democratically governed countries has grown rapidly, and, equally important, the number of autocratic governments that have adopted democratic institutions—such as holding elections and permitting multiparty competition—has also risen (Magaloni, Chu, and Min 2013). Citizens living under both democratic and nondemocratic regimes demonstrate similar democratic norms in holding political leaders accountable for unilateral actions that disregard the legislative process (Chu and Williamson 2025). Additionally, people from diverse cultures coherently and consistently recognize competitive elections and civil liberties as fundamental components of democracy, in the face of growing attempts by certain global actors to redefine democracy (Chu, Williamson, and Yeung 2024).
Scientific Contributions. My primary subfield within political science is international relations. However, due to my interest in the intersection of domestic and international politics, I also contribute to the comparative politics subfield. In this area, my research documents the existence and variation (or lack thereof) of democratic values and norms across different societies worldwide. Contrary to some existing scholarship, my work reveals surprising convergence and consistency in people’s understanding of democratic governance across various societies, including the use of competitive elections to select leaders, the desirability of civil liberties, and the need for political leaders to face checks and balances (e.g., Magaloni, Chu, and Min 2016; Chu and Williamson 2024; Chu, Williamson, and Yeung 2025).
Discovering this empirical regularity is significant to the CP field for at least two reasons. First, it breaks through a gridlocked debate in the field, as prior studies found it challenging to systematically document people’s understandings of democracy due to its multi-dimensional nature across different contexts. My work applied novel research designs to provide fresh insights. Second, many scholars debate the causes of democratic fragility and, these days, democratic erosion and backsliding. These questions are especially puzzling because most people in the world say, at least in the abstract, that they highly value democracy and want their government to be democratic. An influential hypothesis in the literature is that democracy may be weak because people understand democracy in very different ways, so even if they say they like “democracy,” different people mean different things. My research helps rule out this hypothesis so the field can focus on other answers.
My research advances the field’s understanding of how humanitarian and liberal democratic institutions, norms, and social identity influence the domestic politics of war and conflict. In my scholarship, I am particularly focused on producing new knowledge about the impact of individuals, including everyday citizens, elites, and policymakers. My approach contrasts with studies that emphasize the international system, nation-states, and other macro-level factors. Due to my interest in individuals and their political opinions, I frequently employ surveys and experimental survey methodologies. However, my major projects also incorporate other data sources and methods, such as qualitative case studies and macro-level statistical analysis.
Below, I elaborate on my research regarding (1) humanitarianism in the laws of war, (2) the social consequences of liberal democracy in world politics, and (3) democratic values in comparative politics. For each section, I provide a descriptive narrative of my scholarship and explain its significance to social scientific knowledge.
Narrative #1: Can international law humanize people’s opinions about war?
One of human society’s significant achievements in the 20th century was embedding humanitarian principles into nearly universally accepted international laws of war, such as the Geneva Conventions. Optimists argue that this legalization encourages people worldwide to embrace deeper moral commitments to reducing human suffering resulting from war and wartime conduct. This accomplishment should be celebrated, but my research raises new concerns: these laws and institutions interact with human psychology, norms, and identity in ways that limit the impact of international law on society.
To begin, international humanitarian law unconditionally bans certain types of wartime conduct, such as the abuse of prisoners of war. Chu (2019), however, demonstrates that people’s deeply held commitments to reciprocity persist: they largely support reciprocal wartime abuses and are only willing to adhere to international law if other countries commit to doing the same. Thus, in this case, international law can stabilize mutual good behavior, but once one side breaks the rules, the law will struggle to prevent the other side from also breaking the rules.
Relatedly, international law bans all wars except those fought in self-defense or those authorized by the United Nations Security Council. However, according to Chu (2025), international public opinion on war still aligns with a moral and social-psychological logic: people approve of illegal wars that pursue humanitarian aims (i.e., military humanitarian intervention). Furthermore, when assessing the legitimacy of humanitarian wars, people often prioritize fitting in with their social peers over adhering to the rules of universal and legal institutions like the United Nations Security Council.
Second, international norms broadly dictate that we must evaluate people’s intentions to assess the legality of their wartime actions. For instance, the law differentiates between intentionally and accidentally bombing a civilian building. However, people’s psychological predispositions lead them to first respond to the moral harm caused by an action and then infer intentions: if an action causes harm, they tend to assume it was done intentionally. When something bad occurs, people are biased to assume it is a purposeful conspiracy (Chu, Holmes, and Traven 2020; Traven, Holmes, and Chu 2023).
Third, people’s attitudes toward war are significantly shaped by their social identity. For example, according to various international norms and legal doctrine, humanitarian action should, in theory, be taken to save innocent civilians without discrimination. However, in practice, people are more likely to support actions to save people they identify with, particularly along religious lines (Chu and Lee 2024). Similarly, even policymakers express identity biases in their openness to refugees, which should instead be received based on humanitarian standards (Shaffer, Pinson, Chu, and Simmons 2020). People’s attitudes toward post-war reconciliation, such as having their government apologize for war crimes, are also heavily influenced by their nationalistic sentiment or identity-based attachments to their country (Kitagawa and Chu 2021).
Thus, my research ultimately demonstrates that international law shapes society’s understanding of warfare, but people’s preexisting norms, identities, and psychological biases significantly limit the contexts in which it can exert such influence.
Scientific contributions. A fundamental question in the social sciences is whether laws and institutions can shape human behavior, including people’s opinions and moral beliefs. In international relations scholarship, the debate often revolves around optimists who believe that international institutions influence domestic norms and state behavior, versus pessimists who argue that they are primarily ineffective. My research intervenes in this debate with theory and evidence, generally siding with the pessimists. Existing literature reaches its pessimistic conclusions mainly by pointing to macro-level phenomena, such as the observation that countries tend to sign international treaties only when they align with their convenience or self-interest. In contrast, my work demonstrates the micro-level processes through which international law may be limited in its influence, providing new insight into the relationship between rules, institutions, and human values and behavior.
Beyond making theoretical and substantive contributions, my scholarship also advances applied survey methodology in studying the laws of war. Chu (2019), for example, shows how the field’s previous use of “no-information” control groups in survey experiments led to incorrect conclusions about whether reciprocity affects public opinion on war. To provide another example, Blair, Chu, and Schwartz (2022)’s novel application of the list experiment, a survey technique used to reveal people’s hidden beliefs, has helped the field more accurately document people’s true attitudes toward the use of chemical and nuclear weapons during war.
Narrative #2: What are the social consequences of liberal democracy on world politics?
Democracy, especially liberal democracy, creates social divisions in international relations. Liberal democratic countries tend to form an exclusive club or ingroup, and their citizens express this worldview. The social cohesion among democracies enables their leaders to maintain greater domestic support for military alliances by invoking shared values in public rhetoric and diplomacy (Chu, Ko, and Liu 2021). The ideational affinity among democracies also explains why organizations representing the liberal community, like NATO, can exert political legitimacy and influence on citizens and policymakers within its social borders (Chu 2025).
This democratic social identity is not only about building ingroup cohesion; it also creates friction with outgroups. Citizens of liberal democracies, for example, view nondemocratic powers as greater threats to the international system, even after accounting for traditional economic and security factors (Chu 2021). Similarly, policymakers in liberal democracies tend to discriminate against economic investments from autocratic countries, particularly in the context of U.S.-China rivalry (Chen and Chu w.p.). Significantly, political regime and ideology seem to influence these preferences more than factors like race (Chu 2025; Chen and Chu w.p.).
Thus, the social divide between democracies and non-democracies shapes how elites and citizens perceive international relations, leading to significant consequences. The influence of elites is crucial because they formulate policy. Additionally, public opinion is important as it affects policymaking, especially in democratic countries (Chu and Recchia 2022).
Scientific contributions. My work advances international relations theory concerning the link between social identity and (democratic) political regimes, as well as the political consequences of this link on substantive issues like military intervention, alliances, and great power politics. Social identity theory (SIT), initially developed in social psychology, has been widely applied to explain political phenomena. Earlier IR applications of SIT draw from the social constructivist paradigm and focus on macro-level dynamics (e.g., explaining how countries hold identities); however, there have also been breakthroughs in micro-level research.
My work makes fundamental contributions to understanding the impact of liberal democracy on the international system, largely by applying and developing SIT. For example, my book on social cues innovates within SIT to address the following question: why can some international institutions “legitimize” a country’s foreign policy, increasing domestic and foreign approval for that policy? I reframed legitimization as a form of identity politics, where group members sharing a common identity (ingroup members) can influence each other. The book further clarifies the causal process to explain how social cuing works and theorizes why specific institutions can facilitate social cuing among certain audiences (e.g., how NATO mobilizes support among liberal democracies). My theory challenges the dominant explanations in the field, which focus on legitimization from legal, material, and rational-informational perspectives. In conjunction with the extensive empirical work in this book, my research thus develops foundational theory about social identity in politics, while also providing a new answer to an enduring question in the field of IR regarding international institutions and their political legitimacy.
My other research further demonstrates how democratic social identity and values influence China’s global soft power (Chu 2021) and the political rhetoric of military alliances (Chu, Ko, and Liu 2021). I have also applied SIT to explain how racial and religious identities might affect Americans’ support for humanitarian intervention in other countries (Chu and Lee 2024). Collectively, these articles make significant theoretical contributions to understanding how identity, norms, and values operate in international relations, as well as substantive contributions to the understanding of consequential phenomena, such as the nature and determinants of China’s soft power.
Narrative #3: How do people from different societies think about democracy?
Over the last century, most of the world has increasingly embraced liberal democracy, particularly electoral democracy, as a way to organize political society. The number of democratically governed countries has grown rapidly, and, equally important, the number of autocratic governments that have adopted democratic institutions—such as holding elections and permitting multiparty competition—has also risen (Magaloni, Chu, and Min 2013). Citizens living under both democratic and nondemocratic regimes demonstrate similar democratic norms in holding political leaders accountable for unilateral actions that disregard the legislative process (Chu and Williamson 2025). Additionally, people from diverse cultures coherently and consistently recognize competitive elections and civil liberties as fundamental components of democracy, in the face of growing attempts by certain global actors to redefine democracy (Chu, Williamson, and Yeung 2024).
Scientific Contributions. My primary subfield within political science is international relations. However, due to my interest in the intersection of domestic and international politics, I also contribute to the comparative politics subfield. In this area, my research documents the existence and variation (or lack thereof) of democratic values and norms across different societies worldwide. Contrary to some existing scholarship, my work reveals surprising convergence and consistency in people’s understanding of democratic governance across various societies, including the use of competitive elections to select leaders, the desirability of civil liberties, and the need for political leaders to face checks and balances (e.g., Magaloni, Chu, and Min 2016; Chu and Williamson 2024; Chu, Williamson, and Yeung 2025).
Discovering this empirical regularity is significant to the CP field for at least two reasons. First, it breaks through a gridlocked debate in the field, as prior studies found it challenging to systematically document people’s understandings of democracy due to its multi-dimensional nature across different contexts. My work applied novel research designs to provide fresh insights. Second, many scholars debate the causes of democratic fragility and, these days, democratic erosion and backsliding. These questions are especially puzzling because most people in the world say, at least in the abstract, that they highly value democracy and want their government to be democratic. An influential hypothesis in the literature is that democracy may be weak because people understand democracy in very different ways, so even if they say they like “democracy,” different people mean different things. My research helps rule out this hypothesis so the field can focus on other answers.