Comparative-historical analysis (CHA) has a long and distinguished pedigree in political science. In a discipline in which a succession of different movements has advocated new approaches promising more powerful theory or new methodologies for more rigorously testing theory, or both, CHA has stood the test of time. It remains the approach of choice for many scholars spanning all generations and continues to set agendas – both theoretical and substantive – for many other scholars who use alternative analytical and methodological tools.

In this introductory chapter, we explore the resilience and continuing influence of CHA in contemporary political science. We attribute the enduring impact of CHA to strengths built into its very defining features: its focus on large-scale and often complex outcomes of enduring importance; its emphasis on empirically grounded, deep case-based research; and its attention to process and the temporal dimensions of politics. These features not only distinguish CHA but also endow the approach with comparative advantages not found in other research.

The methodological churning within political science is not new, and yet it seems to have intensified over the past several years. Beginning in the late 1980s, the field underwent important changes as rational choice theory made its way into the mainstream of the discipline. Scholarship using game theory was greeted with considerable fanfare and controversy, celebrated by some for the theoretical elegance of its models, criticized by others for the limited leverage that these models often seemed to offer in explaining real world outcomes. Even if this line of work did not have the transformative effects that some predicted, clearly it now occupies an important place in the discipline.

More recently, an empiricist strand of work has emerged with similar energy and force. Billed by its proponents as a “revolution in causal inference,” the experimental method has been sweeping through many departments. Today's experimentalists put great emphasis on research design, often recruiting subjects – in the lab, in the field, or online – to participate in experiments that attempt to isolate the effects of variables of concern.

Until recently, institutionally minded scholars in the social sciences generally treated institutions as fixed. Whether defined as the rules of the political game, the standard operating procedures of bureaucracies, or the regularized norms guiding organizational behavior, institutions were associated with stability and were invoked as independent or intervening variables to explain persistent cross-national differences in outcomes. More recent work in the field, however, has attempted to provide greater insight into how institutions evolve and how institutional effects can change over time. Instead of seeing institutions as largely unchanging features of the political environment, these arguments seek to specify what kinds of institutional changes propelled by what kinds of social processes are most likely under what kinds of political configurations.

This chapter advances this more recent agenda, examining two important, common, and theoretically explicable processes through which institutional effects change over time, which we call “drift” and “conversion.” Drift occurs when institutions or policies are deliberately held in place while their context shifts in ways that alter their effects. A simple example is the US minimum wage, which is not indexed to inflation and thus declines in value as prices rise unless new federal legislation is enacted. Those wishing to effect change through drift need only prevent the updating of existing rules. Drift thus depends on how sensitive the effects of an institution are to its context, whether policies are designed in ways that foster updating in the face of changing circumstances, and whether it is easy or difficult to block such updating.

Conversion, by contrast, occurs when political actors are able to redirect institutions or policies toward purposes beyond their original intent. An example is the ability of corporations to use the Sherman Antitrust Act of 1890 to hinder labor unions. Passed amid widespread concern about corporate collusion, the legislation was meant to break up business trusts that were “in restraint of trade.” Yet corporations managed to convince federal courts that union organizing was “in restraint of trade.”

This volume originated in a conversation in 2010 in which Lewis Bateman of Cambridge University Press expressed interest to James Mahoney in a second edition of Comparative Historical Analysis in the Social Sciences (coedited by Mahoney and Dietrich Rueschemeyer, 2003). The following year, Kathleen Thelen and Mahoney began discussions about a new project along these lines. Although a fresh programmatic statement about comparative historical analysis (CHA) seemed appropriate and much needed, it was also apparent that any new undertaking could not replicate – or even simply update – the earlier book. For one thing, Dietrich Rueschemeyer had retired from sociology, making unavailable the senior leader of the earlier project. Moreover, developments in political science and sociology spoke against following the previous book's approach of simultaneously engaging both disciplines. In particular, the rise of new methodologies and approaches in political science seemed to require a new programmatic statement about CHA focused on political science.

Advances in Comparative-Historical Analysis features original contributions that situate CHA within present-day debates in political science. The book retains the earlier volume's threefold structure – exploring the substantive contributions, theoretical accomplishments, and methodological strategies of CHA. It also follows the earlier book in being a collective effort, bringing together leading CHA scholars who otherwise work in diverse empirical areas. However, the essays in this book cover wholly new topics and tools, and they engage recent and ongoing debates and problems in the field.

To us, this project seemed especially important now because of the excitement surrounding the “revolution in causal influence” currently gripping political science. In recent years, the discipline has witnessed an explosion of interest in the experimental method and a smaller but significant movement advocating the use of “big data.” In light of the growing interest in new techniques for data collection and theory testing, we felt it important to call to mind the ongoing contributions that CHA has made to theory generation the explanation of large and complex outcomes at the macro level – outcomes that newer approaches often shy away from as empirically intractable.