Annual Review of Political Science - Volume 24, 2021

Taking liberalism's measure as an indispensable yet inherently fragile design grounded in the rule of law, government by consent, individual and public rights, and political representation, my work at the intersection of ideas, institutions, and methods to appraise behavior has focused on origins and transitions, membership boundaries and domination, and an unsteady bonding with the older regime model of democracy. Shaped by early and later life experiences and guided by the good fortune of stimulating networks and enabling institutions, my analytical histories of thought and events, primarily in the American experience, have asked when and why liberal democracies become normatively appealing (less closed and more tolerant) and more effective (less vulnerable and more secure). As a political scientist trained in history, I have been keen to advance a discipline that refuses to be enclosed or too crisply divided into subfields, or, indeed, to choose between quests for causality and understanding.

Contrary to stylized accounts of policy making in democracies, it is routine for presidents, governors, and other chief executives to issue directives such as decrees and executive orders to make law on their own. This article evaluates what political scientists have learned about presidential unilateral power. In our view, while a quarter century of scholarship on the topic has yielded a variety of theoretical predictions, the empirical record offers conflicting and perhaps unreliable evidence to substantiate and adjudicate between them. We review the dominant theoretical perspectives, which focus largely on constraints related to the separation of powers and political accountability. We then evaluate the evidence supporting these arguments and conclude with recommendations for conceptual, theoretical, and empirical advancement.

Early research on wartime violence against civilians highlighted a distinction between macro- and micro-level approaches. Macro-level approaches, grounded in the international relations subfield, focus on variation across countries or conflicts, while micro-level approaches, more influenced by the comparative politics subfield, focus on variation within countries or conflicts. However, some of the recent research on civilian targeting does not fit neatly into this dichotomy—such as research comparing subnational units or armed groups across conflicts or research relying on geo-referenced event data for multiple conflicts. We review the literature and advocate moving beyond the language of the micro- and macro-level divide, instead focusing on the determinants of violence against civilians at five different levels of analysis: international, domestic, subnational, organizational, and individual. While acknowledging significant advances in the field, we argue for continued research aimed at developing a more integrated theoretical understanding of the multiple actors and interactive social processes driving violence against civilians.

The global ascendance of populism has produced an explosion of research, bringing together scholarship on American and comparative politics as well as encouraging intellectual exchange among political scientists, economists, and sociologists. A good way to get a handle on what is now a wide-ranging and interdisciplinary literature is to focus on the key debates characterizing it. This article reviews the literature on the causes of populism, and in particular right-wing populism, in the United States, Europe, and other advanced industrial nations generally, but much of this literature draws on and refers to research on other parts of the world as well. This review analyzes the nature as well as the strengths and weakness of demand- and supply-side explanations of populism, economic grievance–based and sociocultural grievance–based explanations of populism, and structure- and agency-based explanations of populism.

Conflict and cooperation do not result from isolated individual actions. In settings such as insurgency, interstate conflict, protest mobilization, and informal governance, actors are highly interdependent. The study of networks aims to identify what the relevant interdependencies are and, crucially, how they shape conflict and cooperation outcomes. Although this is a relatively new research area, its early results convincingly establish that networks matter. Social networks provide information, transmit peer pressure, and structure interactions in ways that help groups overcome social dilemmas. With much research documenting the importance of particular outcomes in particular areas, the next major step will be putting the pieces together. Which connections between actors matter in which circumstances and how? The groundwork has been well laid for this large future research endeavor.

Amid the global resurgence of nationalist governments, what do we know about nationalism? This review takes stock of political science debates on nationalism to critically assess what we already know and what we still need to know. We begin by synthesizing classic debates and tracing the origins of the current consensus that nations are historically contingent and socially constructed. We then highlight three trends in contemporary nationalism scholarship: (a) comparative historical research that treats nationalism as a macropolitical force and excavates the relationships between nations, states, constitutive stories, and political conflict; (b) behavioral research that uses survey data and experiments to gauge the causes and effects of attachment to nations; and (c) ethnographic scholarship that illuminates the everyday processes and practices that perpetuate national belonging. The penultimate section briefly summarizes relevant insights from philosophy, history, and social psychology and identifies knowledge gaps that political scientists are well-positioned to address. A final section calls for more comparative, cross-disciplinary, cross-regional research on nationalism.

For decades, research on US local politics emphasized the distinctiveness of local government, but that has begun to change. In recent years, new data on partisanship and ideology have transformed the study of local politics. Much of the ensuing scholarship has concluded that local politics resembles politics in state and national governments: partisan and ideological. I argue that such a conclusion is premature. So far, this newer literature has been insufficiently attentive to the policies US local governments make—and to the fact that they are mostly different from the issues that dominate national politics. Going forward, scholars should prioritize measurement of preferences on these local government issues, develop theories of when and why local political divisions will mirror national partisanship and ideology, and investigate why there are links between some local policies and national partisanship and ideology—and whether those links also exist for core local government issues.

Grounded in social-contractual ideas about relationships between the governed and those who govern, the provision of social benefits to citizens has historically been predicated on expectations of acquiescence to state authority. However, the rapid expansion of noncontributory social assistance in sub-Saharan Africa, often supported by global donors through technical assistance programs, raises myriad questions about the relationship between social protection and the social contract in fragile and low-capacity contexts. Focusing on sub-Saharan Africa, but drawing on the theoretical and empirical literature on social protection from around the world, this review parses out the redistributive, contractual, and reconstitutive effects of social protection programming on citizen–state relations. We argue that program features—including targeting, conditionality, accountability mechanisms, bureaucratic reach, and the nature and visibility of state–nonstate partnerships—interact dialectically with existing state–society relationships to engender different social contract outcomes for differently situated populations.

This article traces the development of the study of race and class in American political behavior. It starts by challenging the American exceptionalism thesis, particularly its premises regarding the diminutive role of social class and the absence of serious discussions about race. It then critically reviews the conventional scholarship on American political behavior and its reliance on objective indicators of social class as predictors of political preferences and participation. The article also highlights studies that have conceived of class as an important social identity and have thus measured it subjectively. It then discusses the surge of identity studies in the field of race, ethnicity, and politics (REP) and the turn toward an intersectional approach that rarely includes social class. The article ends with a discussion of the handful of studies that do consider the intersections of race and class, and underscores the need for more research of this type to advance our understanding of contemporary American political behavior.

This article reviews the remarkable growth in empirical literature in political science on wartime sexual violence against civilians, including rape, sexual slavery, forced marriage, and other forms. Early work, motivated by ongoing conflicts in the former Yugoslavia and Rwanda, tended to portray these forms of violence as inevitable, ubiquitous, and either opportunistic or strategic. However, recent literature and new data sources have documented substantial variation in sexual violence across countries, conflicts, perpetrators, and victims and survivors. Building on this observed variation, scholars have developed and tested a wealth of theories about when, where, why, and under what conditions sexual violence occurs as well as its consequences. We highlight the core findings from the literature, explain the key debates among experts, and explore several avenues for future research. We conclude by detailing what the study of wartime sexual violence—both the findings and the research process—offers to a broader set of political science scholars.

Scholarship on the politics of secrecy in international relations and foreign policy has experienced tremendous growth in recent years. This article begins by providing an overview of this literature, analyzing the conditions under which leaders opt for secrecy in both economic and security domains. These motivations differ greatly depending on whether the presumed audience from which a leader keeps a secret is domestic, international, or corporate in nature. Next, it considers methodological innovations and challenges, particularly in the measurement of secrecy. Finally, it reflects on the lessons learned and discusses some exciting questions that scholars could explore in future research. As a burgeoning field within international relations, the study of secrecy offers a variety of promising and potentially fruitful directions.

Electoral gender quotas now exist in a majority of national legislatures worldwide. In general, quotas are followed by greater legislative attention to the interests and priorities of women as a group. Across cases, effects have been most pronounced on issues related to women's rights, public health, and poverty alleviation. Quotas can influence policy in two general ways: First, quotas may send cues to all officeholders, prompting broad changes in legislator behavior among both men and women. Second, quotas typically bring more women into legislatures, causing a shift in aggregate legislator preferences and increasing women's ability to collectively influence legislative decisions. Yet, the positive effects of quotas are not universal, and some research reveals instances in which quotas have led to limited policy changes or even to more gender-inegalitarian outcomes. I suggest several variables that may moderate the relationship between quota adoption and policy change, including underexplored dimensions of quota design.

Despite the importance of politicians, empirical work rarely examines who decides to enter politics and why. This survey presents conceptual issues in measuring political entry; reviews work on individual, organizational, and institutional determinants of political entry; and summarizes the main findings and puzzles related to the representation/competence trade-off in recent microcensus studies on who runs for office. Fruitful directions for future work are highlighted throughout the article.

Political scientists are increasingly conducting field experiments that raise ethical issues that standard review criteria and processes are ill equipped to address. Field experiments can answer important questions, but they can also present various harms to individuals, communities, and political processes; undermine autonomy; introduce partnerships that present complex questions of responsibility; and damage the public's trust in the discipline. This article reviews published empirical and theoretical research, professional guidelines, and media accounts, blog posts, and other sources when appropriate. It characterizes the state of the field regarding the identification of ethical problems, relevant normative guidance, proposed strategies for managing ethical concerns, and issues on the horizon. It concludes that the discipline is making good progress, with robust guidelines and strategies for conducting field experiments ethically. However, there is still much work to be done in refining and expanding current guidance, addressing remaining issues, and promoting norms. This review concludes with some general recommendations for researchers conducting political science field experiments.

This article reviews the literature on the persistence of racial cues and appeals in American elections. I focus on three central themes: racial priming, the influence of the Obama presidential campaigns on racial cues, and racial appeals in the context of a diversifying United States. I identify linkages across these domains while also suggesting avenues for future research. I argue that in the context of a diversifying United States, scholars should develop more measures that capture attitudes that are specific to groups other than African Americans. The nation's growing racial and ethnic diversity is also an opportunity to develop and test more theories that explain the political behavior of racial and ethnic minorities beyond the traditional black–white divide. Finally, since much of the research on racial cues focuses on whites’ racial animus, I suggest that scholars spend more time exploring how racial cues influence the behavior of whites with positive racial attitudes.

This article responds to a set of well-known challenges to empirical research on formal institutions in comparative politics. We focus on the case of written constitutions and discuss the scholarly utility of studying such documents in the face of four analytic and theoretical challenges. Each of these challenges, in turn, implies a set of empirical questions, for which we invoke original data to sketch a broad-brushed set of answers. The data analysis and accompanying discussion suggest a set of guidelines for how written constitutions should be deployed in comparative research designs on topics that involve political institutions.

Not all politics is local. Not even local politics is necessarily local. The reemergence of local politics is not comparable to the nationalization of politics but is rather an element making multilevel policies more or less interconnected. This global review (not including North America) suggests that the rise of local politics is explained by three set of processes—(a) democratization, including protest, (b) economic globalization, urbanization, and the deepening of territorial inequalities, and (c) decentralization or deconcentration and the rise of local governance and policies. The rise of local politics is not a revival of the past but an element of the politics of scale taking. All over the world, local politics is increasingly about policies, governance, and political choice.

External validity captures the extent to which inferences drawn from a given study's sample apply to a broader population or other target populations. Social scientists frequently invoke external validity as an ideal, but they rarely attempt to make rigorous, credible external validity inferences. In recent years, methodologically oriented scholars have advanced a flurry of work on various components of external validity, and this article reviews and systematizes many of those insights. We first clarify the core conceptual dimensions of external validity and introduce a simple formalization that demonstrates why external validity matters so critically. We then organize disparate arguments about how to address external validity by advancing three evaluative criteria: model utility, scope plausibility, and specification credibility. We conclude with a practical aspiration that scholars supplement existing reporting standards to include routine discussion of external validity. It is our hope that these evaluation and reporting standards help rebalance scientific inquiry, such that the current obsession with causal inference is complemented with an equal interest in generalized knowledge.

Social scientists are now in an era of data abundance, and machine learning tools are increasingly used to extract meaning from data sets both massive and small. We explain how the inclusion of machine learning in the social sciences requires us to rethink not only applications of machine learning methods but also best practices in the social sciences. In contrast to the traditional tasks for machine learning in computer science and statistics, when machine learning is applied to social scientific data, it is used to discover new concepts, measure the prevalence of those concepts, assess causal effects, and make predictions. The abundance of data and resources facilitates the move away from a deductive social science to a more sequential, interactive, and ultimately inductive approach to inference. We explain how an agnostic approach to machine learning methods focused on the social science tasks facilitates progress across a wide range of questions.

In recent years, the world has seen a rising backlash against globalization. This article reviews the nature, causes, and consequences of the globalization backlash. It shows that, contrary to a popular narrative, the backlash is not associated with a large swing in public opinion against globalization but is rather a result of its politicization. The increasing influence of globalization-skeptic actors has resulted in more protectionist, isolationist, and nationalist policies, some of which fundamentally threaten pillars of the contemporary international order. Both material and nonmaterial causes drive the globalization backlash, and these causes interact and mediate each other. The consequences are shaped by the responses of societal actors, national governments, and international policy makers. These responses can either yield to and reinforce the global backlash or push back against it. Understanding these dynamics will be an important task for future research.