My approach to Sociology

I am fascinated by Durkheim's notion of the “whole does not equal the sum of its parts; it is something different, whose properties differ from those displayed by the parts from which it is formed.” Dynamics in groups, organisations, and societies are often very difficult to explain and seem to be inconsistent with the aims and motives of the individuals that constitute the collective. This suggests that even a model that perfectly captures the patterns of individual behaviour might sometimes fail to explain the behaviour of groups, organisations, and societies.

On the one hand, I am fascinated by the idea that sometimes the whole is more than the sum of the parts. On the other hand, I am convinced that social phenomena (the whole) can be traced back to the behaviour of individuals (the parts). Accordingly, the overarching research question of my research is the following. If the whole is more than the sum of the parts, what is missing on the right hand side of the equation?

To answer this question, I study the following three theoretical ingredients that have an impact on how the behaviour of individuals aggregates to the behaviour of social collectives:



Feedback loops
Sociology is so fascinating but also so challenging because we do not study individuals in isolation. Thus, in order to develop a valid model of social collectives, we need more than a good understanding of individual behavior (which is also not easy). In addition, we need to understand how the behavior of individuals affects others’ behavior and how they, in turn, affect the decisions of others, and so on. These chains of reaction can generate very surprising outcomes. 

A famous example is Schelling’s model of residential segregation. Schelling’s model shows how cities that are perfectly mixed can segregate into ethnically homogenous neighborhoods. Strikingly, Schelling showed that residential segregation emerges even when individuals are very tolerant and accept to live in neighborhoods where their own group is the minority (see animation movie below). Segregation can emerge because whenever an individual moves to another place, she is changing the composition of the neighborhood that she leaves and of her new neighborhood. These changes might motivate individuals who used to be happy with the composition of their neighborhoods to also move away, sparking a cascade of moves that will increase segregation even further.

Another example of an unexpected macro-outcome comes from our work on social-influence dynamics. In one of our models, a population of agents who hold identical opinions at the outset of the dynamics can fall apart into subgroups with maximally opposing opinions, even though the individuals do not seek to distance themselves from others (see the movie at the very bottom of this page). You find more information on this here.


Social Institutions
In the past 10 years, we have witnessed the emergence of new forms of cooperation. People surf couches of strangers; programmers make their code freely available online; laymen team up and create the biggest encyclopedia that ever existed; experts offer help in question-and-answer forums; and people use their private cars as taxicabs. All of these instances of cooperation were completely unheard of just a few years ago.

Some scholars interpret this as a change in individuals’ sociality, arguing that in particular young people have very strong pro-social motives. However, I do not believe that individual motives have changed dramatically. In contrast, new social institutions have been developed that allow individuals to get into contact with others, to place trust in them, and to punish defectors. Uber taxis are a great example, as the Uber app makes it virtually impossible for taxi drivers and customers to hornswoggle each other.

This illustrates that one cannot explain the behavior of individuals without a proper understanding of the institutional setting. In my research, I study how different social institutions (e.g. signaling, peer-punishment, cheap-talk communication) affect individuals’ behavior in social situations. Plus, I try to develop and test theories of the evolution of social institutions. In a recent experiment, for instance, I conducted a tournament of social institutions to test whether social groups that have certain social institutions have a competitive advantage over other groups.


Noise
There is no doubt that a big part of individual behavior follows patterns that can be described by general theories. However, there is also no doubt that individuals often deviate from these behavioral patterns. These deviations are not of great interest for someone who seeks to explain the behavior of isolated individuals. However, when individuals are integrated in a bigger group, deviations can have a decisive impact on the behavior of the collective, even when deviations are rare and entirely random (noise).

I have developed formal models of the intriguing macro-patterns that random deviations on the micro-level can generate. Plus, I conducted a laboratory experiment to test the hypothesis that a micro-model that takes into account random deviations makes more accurate macro-predictions than a model that neglects deviations. What is more, the experiment demonstrated that it is possible to predict the conditions under which random micro-deviations affect macro-patterns.

I believe that noise and its consequences needs to be studied also from an empirical perspective. Obviously, it is challenging to study something that is rare and potentially random. However, a recent paper by Heinrich Nax and myself proves that it is possible. In addition, a recent paper together with Dirk Helbing provided empirical support for the notion that noise on the micro-level can have decisive impact on macro-patterns.



Schelling's model of residential segregation


Opinion polarization without negative influence