Philipp Rehm’s elegant and important book breaks new ground in one of the most tilled areas in the study of advanced industrial democracies: the welfare state. The history of twentieth- and early twenty-first-century democratic politics is in part the history of building, and at times dismantling, institutions that modify market forces through wide-scale social insurance. Scholars looking to explain this history have pointed to numerous factors—most prominently left parties and union strength, but also the structure of business preferences, religious organizations, war, bureaucratic capacity, and strategic electoral calculations. Yet in the face of a seemingly anemic democratic response to rising inequality, the question of why citizens (sometimes successfully) demand state activity, and other times do not, remains a puzzle of not just academic but also social importance.

Rehm’s ambition is to take a step back from the panoply of arguments used to explain welfare states and advance a parsimonious theoretical framework that travels from individual voters to macro-policy outcomes. The concept of “risk” grounds this framework. The author argues that individuals facing more economic risk demand more insurance, and that the structure of social insurance follows from the position of the median voter in varying risk distributions.

What then is risk? Rehm defines it as “the probability of experiencing a bad event” (p. 19). Risk, in this rendering, is clearly not a uniquely modern experience. But for Rehm, the confluence of particular types of risk, largely those experienced with the advent of industrial labor markets and democratic politics, leads to modern welfare states. State intervention via social insurance primarily aims to moderate risks—redistribution across classes is a by-product, not a primary motivator, of action. The author is hardly the first person to theorize risk as a foundation for social policy demand (or success). This book builds on his own earlier work, as well on as classic studies of the welfare state, such as Peter Baldwin’s The Politics of Social Solidarity: Class Bases of the European Welfare State, 1875–1975 (1990); Karl Ove Moene and Michael Wallerstein's “Inequality, Social Insurance, and Redistribution,” American Political Science Review, 95(4), 2001; Torben Iversen and David Soskice’s work on skill specificity (“An Asset Theory of Social Policy Preferences,” American Political Science Review, 95(4), 2001); and Isabela Mares’ The Politics of Social Risk: Business and Welfare State Development (2003).

The novelty of Rehm’s framework lies, however, in the way he theorizes both individual experiences of risk and their social distributions, or “risk inequality.” He conceptualizes social distributions of risk as differing in their mean levels, variance, and structure; and he uses this variation to derive a powerful set of hypotheses about the position of the median voter under varying distributions. Where the risk distribution is skewed to the left—many people face high risk—voters are likely to demand more insurance; where it is skewed to the right—there are few high risk individuals—voters demand less insurance. Rehm argues that these structural features explain cross-national variation and that changes in the distribution of risk, so-called risk flips, precede the critical junctures of social policy development.

Rehm’s attempt to link recent micro theorizing on the welfare state to macro outcomes is both ambitious and successful, offering a framework that illuminates important puzzles in contemporary politics: for instance, why crises sometimes lead to support for expanded welfare provision and at other times provoke a backlash (because crises differentially affect the risk distribution), why countries with similar levels of market inequality often support different types of redistribution (because the underlying risk structure varies), and so on.

Next to this impressive theoretical contribution, Rehm offers evidence that moves from the broad correlations that motivate his argument to its core mechanisms. He uses both existing cross-national surveys and an original multiwave U.S.-based panel study to show that occupational unemployment rates and other measures of material risk do indeed predict preferences. Moreover, he convincingly shows that people are able to accurately estimate both their own objective risk and their relationship to the broader risk distribution. Building on his prize-winning 2012 American Political Science Review article (with Jacob Hacker and Mark Schlesinger), Rehm shows that the joint distribution of risk and income in a polity go a long way toward explaining mean social support for the welfare state (Philipp Rhem, Jacob Hacker and Mark Schlesinger, “Insecure Alliances: Risk, Inequality, and Support for the Welfare State,” American Political Science Review, 106(2): 386–406).

The latter part of the book turns to the thorny question of change. Rehm argues (against the grain of institutionalist welfare-state scholarship) that changes in the welfare state are much like their origins, in that they follow from changes in risk distribution. He demonstrates this argument through case studies of large-scale partially exogenous changes in the structure of risk distribution, using the case of German unification and more recent insurance expansions, as well as a quantitative study of U.S. state-level policy adoption in the Great Depression.

While one could quibble with aspects of the empirics—especially the extremely short vignettes of recent social-policy adoption in Turkey, South Korea, Thailand, and Taiwan—the empirical foundation of the book is impressive. Rehm convincingly shows that those in occupations with more risk demand more insurance, that places where the distribution of risk and income are cross-cutting provide more insurance, and that crises systematically affect welfare demand through the way they alter the risk pool. To connect these three features to a single concept in a clear and productive way is no small feat.

As with any ambitious work, Risk Inequality and Welfare States also raises questions that it does not completely answer. Risk, for Rehm, is often operationalized through labor market risk, but is not fully defined by it. Unlike Iversen and Soskice‘s work, where risk follows from how an individual’s human capital endowment (the specificity of skills) shapes the probability of prolonged income shocks, Rehm defines risk more broadly. Risks can emerge from changes in family structures and uncertainty created by technological shifts but also from institutions themselves. This widening offers the scope for new research, but also hints at analytical complexity that Rehm’s parsimonious approach often moves away from. If risk is endogenous to broader economic institutions, which are themselves political creations, how do we think about the causal priority assigned to risk? The case studies of adoption—particularly those of the U.S. states, where early risk structures often followed from policies built on racial hierarchies and the demands of mobilized populist movements—raise the question of the endogeneity of risk to broader power structures.

In some ways, these questions are external to Rehm’s framework. The author swaps traditional sociological concepts of class, solidarity, and mobilization for risk, voters, and policy. These moves, as mentioned, provide an analytically robust framework, and the insights they yield speak to their value. Nonetheless, scholars who emphasize the role of unions and left parties (the traditional “power resource” school) might question whether the history of welfare states (and their varying distributional character) can be told without theorizing collective mobilization. Risk groups rarely exist, to use Marxist terminology, explicitly “for themselves.” In a model of the political process in which policy largely emerges through diffuse voter preferences, less attention to organizational solidarity and collective action is less problematic, and yet the history of welfare state programs is rife with group mobilization ostensibly aimed at changing power relations. One potentially interesting extension of Rehm’s work, but an extension that may require contemplation of less tractable concepts like power, would involve examining such mobilization.

Rehm has written an important book. His work has already profoundly influenced the fields of social policy and political economy, and Risk Inequality and Welfare States takes these contributions forward in ways that are elegant, ambitious, and ultimately deeply productive for our understanding of contemporary welfare states.