Many analysts seem to agree that, since the election of Lula in 2002, Brazilian politics has been strongly shaped by the conflict between those who favor the Partido dos Trabalhadores (PT)— in power from 2002 until 2016—known as petistas, and those who oppose the party, often referred to as antipetistas. Given that Brazil is a young and unequal democracy with a complex electoral environment, the fact that the country’s political competition is structured around a party organization poses a challenge to existing comparative politics scholarship.

David J. Samuels and Cesar Zucco’s book is an ambitious effort to answer the puzzle of partisanship in Brazil. Their approach has three main parts. They start by proposing a new classification of voters’ orientations toward parties. The authors replace the conventional divide between partisans and nonpartisans with a classification that identifies hardcore partisans (those who like a party and dislike others), positive partisans (those who like a party without disliking others), antipartisans (those who dislike one or more parties without liking a party), and nonpartisans (those who are indifferent toward parties). Based on this conceptual scheme, they argue that the PT was able to gather unexpectedly large levels of mass support because, since its founding, it has used its organizational structure to engage individuals who were already mobilized in civil society. Moreover, once petismo became a widespread social identity in the country, antipetismo also developed as an out-group orientation among some voters. Therefore, antipetismo is not a new phenomenon, predating the PT’s time in power, and is not directly related to the efforts of PT’s political adversaries to build it.

To provide evidence for their argument, Samuels and Zucco proceed in a careful multistep examination of partisanship in Brazil that relies on surveys from 1989 to 2014, survey experiments, and municipal-level data, all of which are analyzed by sophisticated methods and techniques. They operationalize their classification of partisan attitudes and use surveys to show that, although partisans and antipartisans do not differ dramatically in their socioeconomic backgrounds, the latter tend to be less democratic and politically engaged than the former (chap. 2). They also use panel-survey data to show that partisan attitudes are relatively stable in Brazil and demonstrate with survey experiments how those attitudes shape voters’ opinions on issues and policies (chap. 3).

Possibly the most interesting part of the book comes in their examination of the rise and fall of petismo (chap. 4). The authors combine survey data with municipal-level information on the party’s organizational presence and civil society density. They show that the PT’s effort to establish its organizational presence over time was rewarded with higher levels of partisanship mainly in municipalities with higher civil society engagement. This is a novel insight in understanding how parties can foster partisanship in democracies where those attitudes are less likely to develop. Once established, those partisan and antipartisan attitudes translated into consistent voting patterns that are different from those of nonpartisans (chap. 5). The book concludes by showing the extent of partisanship and antipartisanship cross-nationally, using comparative surveys to demonstrate that the patterns observed in Brazil are also present in other countries (chap. 6).

As with any rich scholarly enterprise, the book also opens points to be clarified and further examined. For instance, the authors claim that previous scholars “have underestimated the extent of partisanship in Brazil” (p. 160). On the one hand, like partisans, antipartisans do have parties as reference points in their voting behavior and opinions, as the book shows. On the other hand, antipartisans are not partisans in a crucial sense that matters for the previous scholarship. When studying the institutionalization of new party systems, the key component of partisanship is the positive support for parties and its subsequent translation into support for democratic institutions. As the authors show, antipartisans are more like nonpartisans than partisans in that respect, because they are less democratic and engaged (chap. 2). Because levels of partisanship, in its conventional conception, are low and decreasing in Brazil, there is support for the concerns of the previous scholarship that the authors criticize.

The evidence in the book also suggests that the numerator (partisans) may be even smaller compared to the denominator (electorate). Although the authors investigate the heterogeneity within nonpartisans (antipartisans and nonpartisans), they do not consider how the conceptual heterogeneity that they propose exists within partisans (hardcore and positive partisans) could blur some of the distinguishing behavioral features of partisans demonstrated elsewhere in the book. Samuels and Zucco acknowledge that the proportion of stable partisans is lower in Brazil than in other countries (chap. 3), but do not consider the possibility that heterogeneity in partisan stability could explain heterogeneity in partisan strength. Further evidence of this heterogeneity within partisans appears in the discussion about the decline of the PT. The authors propose that the number of petismo increased during Lula’s two terms and decreased rapidly during Rousseff’s first term because of negative perceptions of the party’s performance in office. They explain that process by raising the possibility that some voters might have weaker and ambivalent partisan attitudes (p. 102), but the authors do not explore how the extent of those weaker attitudes further reduces the numerator that the book often celebrates.

Notably, the book thoroughly explores the analytical advantages of distinguishing antipartisans from nonpartisans in the study of public opinion and elections. Given that this is the main angle by which the book approaches the puzzle, some normative implications of the findings could be further explored. If one considers antipartisans as a separate category from partisans and nonpartisans, it is hard to avoid the conclusion that partisanship in Brazil is indeed lower and declining faster than elsewhere (chaps. 2 and 6). The opposite is true for antipartisanship, which is higher and increasing faster than in most other countries. Moreover, the growing number of antipartisans share the flaws of partisans (motivated reasoning, chap. 3) and of nonpartisans (being less democratic and engaged, chap. 2) while failing to display any of those groups’ democratic virtues. As the book shows, antipartisans turn out to vote and display consistent voting patterns (chap. 5) when compared to nonpartisans, which suggests that they can turn their undemocratic and stubborn political dispositions into electoral results. This point reveals an accomplishment of the book, because it seems to foreshadow the victory of Jair Bolsonaro’s antipartisan and authoritarian candidacy that came months after its publication.

After Samuels and Zucco’s excellent contribution, there should be no doubt that antipartisanship is a phenomenon to be carefully examined in the study of comparative political behavior. By showing how the PT engaged and fostered mass partisanship in an environment where those attitudes are not likely to spread and develop, the book also provides a theoretical framework that challenges explanations for partisanship that are centered on personalist leadership, pork barreling, and clientelism. All in all, this is a mandatory book in the study of Brazilian politics and the subfield of comparative political behavior. Future scholarship must continue exploring the relevant implications of such an outstanding effort, with proper credit to Samuels and Zucco.