Here are a few of the central questions the still haunt Mexican politics that I address in my book, and some nutshell versions of my best efforts to answer them.
1) What were the origins of the PRI, and why did the Mexican Revolution, a notably heterogeneous conflict with a multiplicity of discrete factions, produce a single party-dominated political system?
One of the things I try to do in my book is to illuminate the relationship between the Mexican Revolution and the political system that took root in Mexico in the decades that followed, and to provide a clear explanation of how and why the former produced the latter. This is why I describe my book as "a new genealogy of the modern Mexican political system."
It is very easy and perfectly reasonable to be cynical about the very notion of an "institutional revolution," particularly with the benefit of historical retrospect. It is nevertheless worth remembering that many politicians of the first few postrevolutionary generations took the immense task of institutionalizing the Mexican Revolution both seriously and literally, and the regional Socialist parties that inspired the initial design of the PRI and its predecessors were intended to be the peaceful, institutionalized expression of the Revolution and one of the primary tools for fulfilling its extensive commitments to Mexican citizens. Subsequent failures by the three successive parties of the revolution to make good on those commitments in a sustained and meaningful way are of course a different matter, but we cannot really understand the form those parties took without taking seriously the intentions that inspired their original design.
The Socialists of the Southeast (Campeche, Chiapas, Tabasco and Yucatán) fervently believed that the political system they created via their corporatist political parties, comprised of ligas de resistencia (local organizations that were typically a cross between a trade union and a mutual aid society) that all belonged to a centralized, state-wide umbrella organization, were democratic; however, although elections remained a key element of the Socialists' political practice, by "democracy" they meant state-led progressive reform intended to insure social welfare, labor rights and a more just and equitable relationship between labor and capital, overseen and regulated by the state. Electoral democracy was another matter: unanimity among the Socialist base was the expectation on election day, even when opposition candidates were allowed to run (which they were not always). This was hugely influential as a model for building substantive, durable working relationships between constituents and political elites at the national level. But as it was applied at the national level with the creation of the National Revolutionary Party (PNR) in 1929, much of the idealism and reformist fervor was stripped away, leaving a powerful tool for organizing popular support for politicians, whether or not they planned to uphold revolutionary principles. No opposition faction was nearly successful at building a durable political party during the 1920s. What's more, in nearly every case, the powerful parties that did emerge either failed or declined to build substantive and lasting relationships with popular constituencies. Lastly, most opposition leaders were either dead or in exile by 1929 (see below re: violence). For all of these reasons, the PNR, which borrowed liberally from the Socialist model, was able to dominate the political system so thoroughly from a very early point, and no tradition of multi-party competition was established.
2) Why did that system work for as long as it did, and why was/is it so hard to uproot it?
As idealistic as southeastern Socialism inarguably was in its design, it always had some authoritarianism in it, too. This varied a bit from state to state: the most authoritarian version of Socialism in the region was in Tabasco, which, for various reasons, was the brand of Socialism that ended up being most influential at the national level. Some of that had to do with the personality of Tomás Garrido Canabal, who led the Socialist party and movement there, but some of it was also about local circumstances. With good reason, Socialists across the Southeast felt that they had to protect their hard-won political rights at all costs in the face of a constant onslaught of well-financed counterrevolutionary attacks against them by local elites whose political power and economic prospects were substantially threatened by Socialist governments. This was all the more true after the assassination of Felipe Carrillo Puerto of Yucatán, the leader of Socialism across the region, in January of 1924, by delahuertista rebel forces, almost certainly with the enthusiastic support of local henequen barons. The Socialists accordingly designed their parties and their movements to be as impervious as possible to attack by reactionary outsiders. In practice, this impulse made the Socialist political system less democratic and party leaders less tolerant of organized challenges to Socialist dominance. Socialists (again, especially in Tabasco), were extremely determined to give no ground to their opponents or enemies, and created a political system that was extremely difficult to reform, in which there was very little opportunity for participation in the political system outside of the Socialist party and the ligas de resistencia. At the same time, there were real, material incentives for citizens to work within the system: workers in Tabasco had some of the highest wages and most extensive workplace protections in Mexico by the early 1930s. The same general arrangement eventually also turned out to work very well at the national level, although with the same weaknesses and liabilities in practice in the long-term.
3) What is the long-term relationship between Mexico's postrevolutionary process of state formation, and state-sponsored (and/or tacitly sanctioned) violence?
It is commonly suggested that the assassination of Alvaro Obregón in 1928 was the catalyst for the formation of the single party-dominated system in Mexico. It is indubitable that it was critically important to the ability of Plutarco Elías Calles and his allies to marshal the majority of the Mexican political class into the PNR once it was founded in 1929. But other deaths also made this possible. The history of southeastern Socialism makes this plain. Felipe Carrillo Puerto was assassinated by counterrevolutionary forces in 1924. Socialist governor Carlos Vidal of Chiapas was killed in the Huitzilac Massacre of 1927, after he helped to lead the movement that opposed Obregón's reelection to the presidency in 1928; by that time he had already survived at least two previous assassination attempts. Hundreds of people who joined the anti-reelectionist movement were also killed, in addition to the opposition presidential candidates, Generals Francisco Serrano and Arnulfo Gómez. Meanwhile, their sympathizers were purged out of the federal legislature, and effectively silenced under the implied threat of further violence. Tomás Garrido Canabal survived the 1920s, but barely: there were several attempts made on his life, just none that succeeded. By the time Calles and his allies convened the PNR, very few opposition leaders were left standing. Some, like Serrano and Gómez, had been killed. Others, like Jorge Prieto Laurens, Adolfo de la Huerta and José Vasconcelos, had fled into exile. Likewise, radicals who were allied with Calles were sidelined or killed, Carrillo Puerto being the most important example (and Garrido Canabal being the most important counter-example), meaning that there were many fewer powerful voices to object to the PNR's turn away from land and labor reform than there once were. At the same time, it is important to recognize that while Mexico had no postrevolutionary purges on the scale of Russia, China or Cuba, the lived experience and firsthand witnessing of violence was deeply influential to the framers of the modern Mexican political system, as well as to everyday citizens who had seen that you could very conceivably be killed for voting a particular way on election day.
In sum, on the one hand, the bloody attrition within the political class over the course of the 1920s made possible the creation of a single party-dominated system by ridding those left standing of thorns in their collective sides, like Gómez and Serrano. On the other, the framers of the PNR designed a political system with the prevention of recurring political violence very much in mind. Nevertheless, targeted political violence was deeply embedded in the foundations of the party and the system it and its successors collectively dominated for so long, from the outset.