Some historical junctures loom larger than others in the imaginations of political scientists. These may be the wars, revolutions, economic collapses, or other big events that have reshaped states and societies. They may be student uprisings, sovereign debt crises, terrorist attacks, or other events that equally have impacted the path of polities. But not all junctures leave legacies. Not all junctures are “critical,” at least not if understood as an interval of time that marks a substantial change from the past. Some junctures may be less important for explaining later outcomes, and exaggerated attention to them may mask the actual reasons for those outcomes. For this among other reasons, researchers must remain open to examining other, prior junctures for their potentially lasting impact. However, where to stop that pursuit remains a thorny challenge for political scientists. How to deal with this so-called infinite regress problem is the core methodological rationale behind this volume.

No body of scholarship has made it a bigger priority to find solutions to the infinite regress problem than that which has become known as the critical juncture tradition. And at fully nineteen chapters and four weighty appendices, no collection offers a more complete account of this tradition than David Collier and Gerardo L. Munck’s edited volume, Critical Junctures and Historical Legacies: Insights and Methods for Comparative Social Science. It is a superbly edited book that details the stakes in critical juncture analysis and offers extensive guidance for how it can be used in qualitative historical research to answer whether and how specific junctures impacted “big” political developments, for example: levels of economic development after colonialism, the purpose and stability of international order after wars end, the organization of civil society after student uprisings, the social consequences of debt crisis, and more. The volume argues that a juncture is critical when it has identifiable legacies, which are understood as cases of “discontinuous change.” If there is no meaningful legacy of change beyond that which would have been the case without a juncture, then the juncture is not critical. This distinction helps resolve the problem of infinite regress.

The volume carefully reviews the existing literature on historical junctures, details the rationale for the editors’ approach, and provides extensive empirical illustrations to make a persuasive case for critical juncture analysis as a major element of the discipline’s methodological toolbox. The first section is devoted to “Basics” and opens with an excellent chapter by David Collier who details a “five-step template” with which to study historical discontinuity. The five steps concern “antecedent conditions,” “cleavages and shocks,” the “critical juncture” itself, its “aftermath,” and any “legacies” and are each carefully discussed in the context of classics and recent research contributions to comparative politics. Three chapters follow by distinguished scholars who recount how their answers to “big substantive questions” can be productively informed by critical juncture analysis. James A. Robinson examines the legacies of colonialism for paths of economic development; G. John Ikenberry examines how postwar settlements shape international political orders; and Sidney Tarrow probes the legacies of the 1960s for social mobilization in later decades.

The second section on “Frameworks and Methods” starts with Gerardo Munck’s careful dissection of how distinct challenges in critical juncture analysis can be resolved, including how to conceptualize the infinite regress problem. For Munck, critical junctures are “qualitative novelties” that designate a “before” and “after” that jointly furnish a “point of entry into the stream of history.” Other contributions entail friendly critiques, such as the deeply engaging chapter by Rachel Beatty Riedl and Kenneth M. Roberts, who contend that critical juncture analysis at times employs overly static concepts. They urge more flexibility, especially in how antecedent conditions and contingency are understood; for example, Riedl and Roberts argue that studies must be more open to considering degrees of contingency and different strengths to antecedent conditions. David Waldner wishes that studies in this tradition would double-down on causal identification and would be more precise in how they address the “problem of backdoor paths.” These are situations where an outcome (Y) is produced not directly by a factor (X), but where X impacts a different factor (Z) that in turn causes Y. For Waldner, attention to potential backdoors is a better long-term solution than taking refuge in notions of contingency when theorizing why X sometimes causes Y and sometimes not. Munck closes the section on a collaborative note and suggests that the standard qualitative methods used by scholars in this tradition can be productively complemented by quantitative analysis.

The gears shift in the third and fourth sections to the application of critical juncture analysis in the study of political regimes and neoliberalism, mostly in Latin America. Sebastian L. Mazzuca looks at the role of state formation for economic performance over two centuries in South America. Ruth Berins Collier, who authored foundational texts in the tradition, concludes that critical juncture analysis of internal (national) dynamics more fully explains the varied ways in which labor was incorporated into the political coalitions and regimes that took form in Brazil, Chile, Mexico, and Venezuela in the 1940s than do analyses focused on international factors. Kenneth M. Roberts studies the origins and impact of the neoliberal transition in Latin America and reveals that standard critical juncture analysis struggles to explain incremental patterns of change. Samuel Handlin identifies the uses and limitations of critical juncture analysis for understanding contemporary developments in the political systems of Latin America. Timothy R. Scully uses the case of political reforms in Chile to make an impassioned plea that researchers be patient in accumulating evidence and letting time pass, or, he warns, they will risk identifying “false positives” when searching for the sources behind durable change.

A smaller number of chapters reach beyond Latin America, principally to Europe. Andrew Gould examines the influence of religion on political liberalism, Robert M. Fishman examines the impact of democratization on culture in Spain and Portugal, and Danielle N. Lussier and Jody LaPorte inquire into the legacies of Communist rule for political developments in Eastern Europe. Beyond brief mentions of developments in Africa and Asia in some of the early chapters, there is not much coverage outside Latin America and Europe. While this is bound to disappoint researchers who are focused on Africa, Asia, the Middle East, North America, and other regions, the silver lining is that there now exists an analytical springboard from which to begin such explorations.

While this volume is a celebration of the contributions of critical juncture analysis, the editors are not shy to feature criticisms and acknowledge limitations. In two notable contributions, Taylor C. Boas and Robert R. Kaufman urge researchers to recognize some inherent limitations in critical juncture analysis. Boas underscores that any attempt to study the present and recent past must let considerable time pass before they have their claims “fully evaluated,” which makes study of the present or recent past an inherently risky and analytically imprecise affair. Meanwhile, Kaufman suggests that this type of analysis is overly focused on examples of discontinuous change and does not recognize that the sources of continuity may also be found in historical junctures.

Critical Junctures and Historical Legacies concludes with a chapter by Munck, who makes a passionate case for continuously refining the means scholars use to determine if, when, and how the past has critical legacies. In considering Munck’s sage advice, researchers also may want to consult the four inspired appendices that feature a coded literature review, a glossary, a bibliography, as well as a brief summary of eight classical texts. Altogether, this volume is a milestone in critical juncture analysis that will serve as a major resource for seasoned and early career researchers alike.