Latent Space and Social Psychological Models of Diffusion

The problem of social diffusion has animated sociological thinking on topics ranging from the spread of an idea, an innovation or a disease, to the foundations of collective behavior and political polarization. While network diffusion has been a productive metaphor, the reality of diffusion processes is often muddier. Ideas and innovations diffuse differently from diseases, but, with a few exceptions, the diffusion of ideas and innovations has been modeled under the same assumptions as the diffusion of disease. In this dissertation, I develop two new diffusion models for "socially meaningful" contagions that address two of the most significant problems with current diffusion models: (1) that contagions can only spread along observed ties, and (2) that contagions do not change as they spread between people. I augment insights from these statistical and simulation models with an analysis of an empirical case of diffusion - the use of enterprise collaboration software in a large technology company. I focus the empirical study on when people abandon innovations, a crucial, and understudied aspect of the diffusion of innovations. Using timestamped posts, I analyze when people abandon software to a high degree of detail.

To address the first problem, I suggest a latent space diffusion model. Rather than treating ties as stable conduits for information, the latent space diffusion model treats ties as random draws from an underlying social space, and simulates diffusion over the social space. Theoretically, the social space model integrates both actor ties and attributes simultaneously in a single social plane, while incorporating schemas into diffusion processes gives an explicit form to the reciprocal influences that cognition and social environment have on each other. Practically, the latent space diffusion model produces statistically consistent diffusion estimates where using the network alone does not, and the diffusion with schemas model shows that introducing some cognitive processing into diffusion processes changes the rate and ultimate distribution of the spreading information. To address the second problem, I suggest a diffusion model with schemas. Rather than treating information as though it is spread without changes, the schema diffusion model allows people to modify information they receive to fit an underlying mental model of the information before they pass the information to others. Combining the latent space models with a schema notion for actors improves our models for social diffusion both theoretically and practically.

The empirical case study focuses on how the changing value of an innovation, introduced by the innovations' network externalities, influences when people abandon the innovation. In it, I find that people are least likely to abandon an innovation when other people in their neighborhood currently use the software as well. The effect is particularly pronounced for supervisors' current use and number of supervisory team members who currently use the software. This case study not only points to an important process in the diffusion of innovation, but also suggests a new approach -- computerized collaboration systems -- to collecting and analyzing data on organizational processes.

The Didache and Traditioned Innovation: Shaping Christian Community in the First Century and the Twenty-First Century

Church leaders, both lay and clergy, shape Christian community. Among their central tasks are: building communal identity, nurturing Christian practices, and developing faithful structures. When it comes to understanding the approach of the earliest Christian communities to these tasks, the Didache might well be the most important text most twenty-first century church leaders have never read. The Didache innovated on tradition, shaping the second generation of Christians to meet the crises and challenges of a changing world.

Most likely composed in the second half of the first century, the Didache served as a training manual for gentile converts to Christianity, preparing them for life in Christian community. This brief document, roughly one third the length of Mark’s gospel, developed within early Jewish-Christian communities. It soon found wide usage throughout the Mediterranean region, and its influence endured throughout the patristic and into the medieval period.

The Didache outlines emerging Christian practices that were rooted in both Jewish tradition and early Jesus material, yet were reaching forward in innovative ways. The Didache adopts historical teachings and practices and then adapts them for an evolving context. In this respect, the writers of the Didache, as well as the community shaped by its message, exemplify the pattern of thinking described by Greg Jones as “traditioned innovation.”

The Didache invites reflection on the shape and content of Christian community and Christian leadership in the twenty-first century. As churches and church leaders engage a rapidly changing world, the Didache is an unlikely and yet important conversation partner from two millennia ago. A quick read through its pages – a task accomplished in less than half an hour – brings the reader face to face with a brand of Christianity both very familiar and strikingly dissimilar to modern Christianity. Such dissonance challenges current assumptions about the church and creates a space in which to re-imagine our situation in light of this ancient Christian tradition. The Didache provides a window through which we might re-examine current conceptualizations of Christian life, liturgy, and leadership.

This thesis begins with an exploration of the form and function of the Didache and an examination of a number of important background issues for the informed study of the Didache. The central chapters of this thesis exegete and explore select passages in each of the three primary sections of the Didache – the Two Ways (Didache 1-6), the liturgical section (Didache 7-10), and the church order (Didache 11-15). In each instance, the composers of the Didache reach back into a cherished and life-giving aspect of the community’s heritage and shape it anew into a fresh and faithful approach to living the Christian life in a drastically different context.

The thesis concludes with three suggestions of how the Didache may provide a resource for the way the Church in the present thinks about training disciples, shaping community, and developing leadership structures. These conversation starters offer beginning points for a richer, fuller discussion of traditioned innovation in our current church context. The Didache provides a source of wisdom from our spiritual forebears that modern Christian leaders would do well not to ignore. With a look through the first century window of the Didache, twenty-first century Christians can discover fresh insights for shaping Christian community in the present.