In the 2000s, the “pink tide” was all the rage in Latin America. The term typically refers to the electoral success of parties on the left. Starting in the late 1990s, it seemed as if country after country in the region was electing leftist parties to office, often by a landslide. By 2010, at least 11 Latin American countries were governed by pink candidates. Political scientists were puzzled—why was this happening? In political science, theories that seek to explain the vote are plentiful. Queirolo therefore needed a research design that would allow her to test a great number of competing explanations—and what is even harder—yield a new one. She succeeded.

Her answer is that the left in the 2000s emerged as a result of voters wanting to try something different (a “new alternative”), but also something cleaner. Rather than a preference for leftist policies per se, or a repudiation of prevalent market policies, Latin Americans wanted change, and they wanted clean parties to bring it about. In the author's words, Latin American voters are driven by “outcome” preferences, not by “policy” or “partisan” preferences.

Queirolo is at the top of her craft when it comes to debunking myths. The first important myth is the idea that the pink tide was a novelty. When it began, in the late 1990s, many analysts heralded it as unprecedented—the first time that popular, equity-oriented parties had managed to come to power in the region. But Queirolo shows that the region has had “ideological cycles” in the past, and that the left was a previous favorite. To prove this point, she makes a methodological innovation by enhancing an existing method. That method was developed by political scientist Michael Coppedge for classifying parties on a left-to-right spectrum. Queirolo's exercise was not without problems, but the results are truly eye-opening. It turns out that the left was predominant in Latin America during a previous cycle (1969–1976) and at least as competitive as the right in another cycle (1956–1968). In other words, the 2000s did not bring in a new era but rather repeated a phase in a cycle.

The second set of myths Queirolo debunks is the idea that the current phase represents a rejection of the neoliberal policies predominant in the 1990s, or conversely, a sign of “disadvantaged classes” rising politically, or something even simpler—a mere reflection of economic indicators. Using data from 1980 to 2010, Queirolo finds no confirmation for any of these variables. Regarding neoliberalism, she finds no correlation between the depth of neoliberal reforms and the pink tide. Think Mexico and Venezuela. In Mexico, neoliberalism went far in 1990s, but the left stagnated in the 2000s. In Venezuela, the reverse was true. Regarding class, Queirolo finds that successful leftist parties have built cross-class coalitions, rather than relying exclusively on the have-nots. And regarding economic variables, Queirolo finds no clear correlation between macroeconomic or personal income variables and the vote for the left. The only economic factor that matters is high levels of unemployment. But even there, the variable is only meekly influential.

If it isn't ideology or economics, what then is the explanation for the pink tide? It's the combination of voters being somewhat inclined toward risk-taking and the belief that leftist parties are decidedly “untainted.” Using survey data about voter characteristics and views, Queirolo shows that voters chose the current crop of leftist parties because they were interested in trying a new alternative as a way to improve the status quo, in line with what prospect theory would suggest. And they chose parties on the left simply because they were not in power and thus could easily bill themselves as “alternative.” But here is a big catch: only those leftist parties that had never before never been in charge of government and were therefore not responsible for the country's welfare were preferred.

This latter point is the centerpiece of Queirolo's notion of untainted parties and the book's most significant theoretical contribution. She argues that where leftist parties were competing against other untainted parties, they did not necessarily enjoy an electoral advantage. To make this point, she takes three case studies: Uruguay, Brazil, and Mexico. In Uruguay and Brazil, the left (Frente Amplio and the Partido dos Trabalhadores, respectively) prevailed, whereas in Mexico the leftist PRD lost because it faced competition from another untainted party, the center-right PAN.

Here is where one might begin to quarrel a bit with Queirolo. While the Uruguay and Mexico cases prove her point well, the Brazil case seems a stretch, mostly because the Partido dos Trabalhadores had had ample experience in (sub-national) office prior to Lula's election. To explain the party's rise, Queirolo thus needs to stress the notion of the party's credibility, rather than its lack of taint. This seems a bit of a deviation, not to mention a too-subjective appreciation.

Further, Queirolo could have tested two other arguments: whether the rise of the left has had anything to do with commodity dependence (a structural argument) or party-system collapse (an institutional argument). It may seem unfair to demand that more variables be included in Queirolo's models, but these two arguments have been strongly argued by others in the field. Because Queirolo makes little mention of them, she misses an opportunity for wider debate.

Finally, the classification of parties as left or right is, as always, problematic. Queirolo knows this, and she thus does one of the best jobs I have seen to defend and improve the classification scheme that she adopts. Yet, the possibility of making subjective judgments, or of simply relying too much on how parties describe themselves, or what a few experts agree on, is still there. More important, even by Queirolo's admission, the methodology does not always work. Parties that could not be classified either way were therefore omitted from the dataset. For example, Queirolo does not include the Peronist Party in Argentina in several elections nor the Partido Reconstrução Nacional in Brazil (in 1989), nor the Partido Verde, also in Brazil (2010).

In almost every country she has studied, there is at least one party that wins at least 20 percent of the vote in at least one election that Queirolo's methodology cannot classify as either left or right, and which therefore is omitted from her tests. These exclusions are too large for comfort.

Even with the preceding taken into account, Queirolo has made a significant intellectual achievement. By stressing the notion of untainted parties she has provided a most nuanced understanding of Latin American voters, who are, at their best, bounded risk-takers. At some point, they get dissatisfied with incumbent parties and seek out new representation. And in experimenting, Latin Americans are not entirely reckless—they choose newness (hence their risk-taking) only after applying an important quality test centered on untarnished performance. Latin American voters are both risk-takers and reassurance-seekers.

One could walk away from this book feeling quite optimistic. Queirolo's depiction of the Latin American voter is exactly what democratic political systems need in order to generate leadership rotation and renewal, and thus stay democratic. Yet, I would still urge caution. One might wonder, for instance, what has happened to these Latin American voters since the late 2000s, when they started reelecting leftist parties that were no longer untainted, and in fact, the source of world-class corruption scandals. It seems that we will need additional studies to understand why the current ideological cycle has lasted longer than Queirolo would have predicted. But that still does not diminish the point that Queirolo has offered one of the best explanations in the literature for the origins of all this pink.