Ideological Entrepreneurs and the Diffusion of Radical Innovation Martin Luther’s Personal Ties and the Spread of the Early Reformation* Sascha O. Becker Yuan Hsiao Monash University University of Washington Steven Pfaff Jared Rubin University of Washington Chapman University 9 August 2019 Abstract What makes societies adopt radically new institutions and ideas, especially when they are likely to face (often violent) resistance? Is there room for ideological entrepreneurs in this process? We address these questions in the context of Martin Luther’s effect on the early spread of the Reformation, one of the most important religious, political, and economic events of the last millennium. We employ multiple newly-digitized panel datasets: the universe of known letters Luther sent in his early career, the towns he visited, and the locations of publication of Luther’s works. We use these data to construct a network of Luther’s pre-Reformation contacts. Comparisons to trade networks indicate that towns in which he had ties were significantly more likely to adopt the Reformation in its early “bottom-up” stages. JEL codes: D85, N34, Z12, N44, C81 Keywords: Martin Luther, Reformation, networks, diffusion, social movements * We thank Robert Barro, Benjamin Elsner, Sean Everton, Rachel McCleary, James Moody, Kevin O’Rourke, Alejandra Ramos, Mara Squicciarini, Guido Tabellini, Noam Yuchtman, and participants in workshops at Bocconi University, Trinity College Dublin, Warwick University, the 2019 ASREC Conference, the 2019 Symposium on Quantitative History (Yantai), and the North American Social Networks Conference for helpful comments. Song Yuan and Hannah Ravitch provided excellent research assistance. All errors are our own. I. Introduction How important are leaders for the spread of social and political movements? Even if we accept that the presence of a leader is important, does it matter who leads? Leaders are often ideological entrepreneurs, who reframe grievances and offer new ways of understanding the world. Leaders can help overcome practical issues such as coordination and collective action problems. They can also help formulate a coherent ideology that binds the movement together and attracts new followers. They model courage and commitment to the cause. All this may be especially important for movements that disturb the status quo, since followers may face serious, even violent, repercussions for joining the movement. In addition, effective leadership may make the movements they lead especially infectious by crafting persuasive appeals and by forging personal ties to sympathizers and potential supporters. Intuitively, we know that leadership can make an enormous contribution to the spread of movements. But how important are ideological innovators like Martin Luther King or Nelson Mandela to the success of their movements, conditional on other factors? Identifying the unique effect of such figures is difficult: we rarely have counterfactual worlds that exclude those individuals. Without such counterfactuals, it is difficult to parse out the role that ideological entrepreneurs play relative to macro or institutional phenomena.1 Network data provides a solution. Leaders influence people to achieve success, and via the connections made by the leader we can capture the scope of their influence. To isolate the role of ideological entrepreneurs, we need significant data about the individuals and their network—who they knew, what they did, where they went—to estimate their influence. Moreover, we need 1 A recent literature in economics suggests that “superstars” can affect a host of economic and scientific outcomes (Johnson et al. 1985; Bertrand and Schoar 2003; Jones and Olken 2005; Azoulay et al. 2010; Waldinger 2010; Moser et al. 2014; Borowiecki 2017). 1 network data to be able to simulate the spread of a movement with and without the unique role played by the leader. In this paper we provide insight into the role that leadership can play in facilitating social and political movements by studying the network of the leader of one of the most important movements of the last millennium: Martin Luther, the father of the Reformation. Within a decade of Luther’s posting of the Ninety-Five Theses in 1517, many towns and cities across the Holy Roman Empire adopted the reforms Luther advocated. In a little over a decade, about ten percent of German cities were already Protestant, a share that would expand much further after 1530 (Rubin 2014). Yet, Luther did much more than simply spark the Reformation. Over its first decade, Luther was its tireless proponent and leader, risking his life to defy the will of the emperor and the pope, reorganizing Wittenberg University to provide it with an institutional home, printing a blizzard of pamphlets, and writing hundreds of letters that facilitated its spread. The combination of his intellect and organizational capabilities raises the question of whether an event as monumental as the Reformation could have succeeded without someone so capable leading it. We analyze the role that Luther’s personal influence—as determined by a newly-digitized data set of his personal correspondence, the tracking of places he visited, and the students he taught— played in the early spread of the Reformation. Specifically, we ask whether the social network ties between Luther and the cities forged by correspondence, visits and teaching, can help explain the early adoption of Protestantism by German towns and cities.2 To test whether personal ties to Luther made a city more prone to adopt Protestantism, we code a number of characteristics of Luther’s ego-centric network as revealed by his collected correspondence, visits, and students by 2 In social network analysis, social ties between people are relations that serve as conduits through which information, opinions, resources and influence can flow. The spread of religious movements is a topic especially well-suited to social network concepts and methods, as recently demonstrated by Everton (2018). 2 the end of 1522. This period represents the formation of Luther as a dissident theologian, prominent critic of the Roman Church, and proponent of radical religious reform. It ends before the formal adoption of Protestant reforms, which began in 1522 following Luther’s defiance of the emperor and the pope at the Diet of Worms in 1521 and his year-long protective incarceration on the Wartburg. Our study contributes to both empirical and theoretical puzzles. Empirically, our analysis sheds new light on one of the great, enduring puzzles in the social sciences: why the Reformation spread so rapidly and where it did so (for a review of the literature, see Becker, Pfaff, and Rubin 2016). This is a puzzle because previous attempts at reform, many of which raised similar complaints to Luther were violently suppressed or failed to diffuse widely. It has been argued that, on the demand side, the increasingly temporal and avaricious actions of the Church placed numerous “consumers” on the “margin of defection” from the Roman Catholic Church (Ekelund et al. 2002). Yet, this had been the case for centuries—focusing only on the demand side leaves the “when” and “where” questions unanswered. On the supply side, the recent spread of the movable type printing press (invented in 1450 by Gutenberg in Mainz, Germany) helped the reformers rapidly spread their anti-papal propaganda before the Church and its secular allies could respond. Rubin (2014) finds that cities that were early adopters of the press were 29 percentage points more likely to be Protestant by 1600.3 However, even if the press were important for spreading the message of the reformers, social network theory suggests that the success of a movement in the face of (probable and violent) resistance requires broad social influence on the part of the initial instigators (Centola 2018; 3 Another important factor allowing for the spread of the Reformation was the Ottoman advance into South-Eastern Europe (Iyigun 2008). The Ottomans threatened the eastern flank of the Holy Roman Empire—reaching the gates of Vienna—at precisely the time of Luther’s movement. This diverted Catholic resources away from Luther’s movement and towards the more “existential threat” imposed by the Ottomans (Iyigun 2015). 3 Centola and Macy 2007). Otherwise, not enough individuals will join the cascade of revolt, even if their private preferences are that it succeeds (Granovetter 1978; Oliver 1993; Kuran 1989, 1995; Lohmann 1994; Rasler 1996; Kim and Bearman 1997; Siegel 2009; Slater 2009; Ellis and Fender 2011).4 Rubin (2014) found that cities which were early adopters of printing were about 29 percentage points more likely to adopt Protestantism. Does printing account for the rapid diffusion of Protestantism? Whereas printing could have facilitated the spread of the Reformation chiefly through the mechanism of informational diffusion, 5 the role of relational diffusion has been relatively neglected in explaining the rise of Protestantism.6 Social relations are implicated in the diffusion of the Reformation because the spread of heterodox ideologies and their institutionalization relies not only on private “infection” through contact with a novel idea, but rather active conversion to and the promotion of that new faith through collective action. An extensive literature in the social sciences has shown how movements tend to diffuse not through ideological infection but through social linkages between actors (Centola 2018; Hedström 1994; Hedström, Sandell,