Funded Grants

Complexity and Diversity

Diversity seems to be on everyone's mind these days. Universities want to build on it. Businesses want to manage it. Politicians and religious leaders want to embrace it. Despite its prominence, more than two thirds of American college campuses require a diversity course, and consulting firms with expertise in diversity training abound, diversity is not well understood. There is little formal theory of diversity. The goal of my research is to develop such a theory by constructing Foundational models of diverse, complex systems.

This effort belongs to the larger agenda to develop complex systems' theory. Complex systems models are typically agent-based. The agents, who could be amoeba or nations, satisfy four criteria: (i) they are diverse, (ii) they are adaptive (iii) they interact locally and, (iv) they exist in dynamic environments. Complex systems exhibit perpetual novelty, they generate emergent behavior at the macro level that might not have been predicted from their micro Foundations, and they are often robust. The science of complex systems attempts to explain these and other phenomena.

I focus on diversity for three reasons: its prominence, the abundance of data, and its scientific interest. Diversity awareness is high because America is becoming more diverse while simultaneously the world is becoming more interconnected. These two facts drive the movement toward the aforementioned diversity courses. In these courses, students learn about identity diversity and its implications for how people interpret their worlds. But identity diversity differs from economic, biological, and ideological diversity in important ways. Basic theory will help us explain how and why these differences matter.

My second reason for focusing on diversity is data availability. A few years ago, you could find only a handful of studies of the impact of identity diversity on businesses, organizations, and schools. Today, the number of such studies is enormous and growing.

In ecology, there are several studies that analyze ecological robustness as a function of species diversity. And the fossil record itself, offers a compelling time series on the rise and fall of diversity levels. There are also data sets on language, cultural, and product diversity, not to mention diversity in clothing, gestures, and architecture.

My final motivation stems from the scientific questions, which, absent public interest, would remain compelling. Why does diversity arise? Do systems tend to evolve too much diversity or too little? Can simple interventions tune diversity to the ensure robustness or efficiency? Does agent?level diversity increase system level efficiency? Or, does the context determine the answer? So economists would see diversity as good but some sociologists seeing it as creating problems. Does diversity increase robustness, as ecologists suggest? Or is the relationship more complex, as political scientists might argue, on the one hand pointing to uprisings in Uganda and the former Yugoslavia as examples where diversity provided fuel for nationalistic uprisings. While on the other hand, demonstrating that one cause of the Civil War was an economic cleavage between the South and the North and the lack of natural coalitions that crossed the Mason Dixon line. So, in this case, a lack of diversity fueled the secession movement. It appears that a complete theory of the interplay between diversity and robustness must explain why economic diversity ensures robustness, but ethnic diversity undermines it.

My theory building process has three steps: first, building a suite of computational models to generate insights; second, the derivation of general theories, concepts, and insights; and third, the creation of a representative computational model that captures the main features of the theory. I have begun or completed three projects in the area of diversity and complexity. Lu Hong, a mathematical economist, and I develop a model of diverse problem solving agents endowed with perspectives (problem representations) and heuristics (thinking tools). We create thousands of agents and form teams of problems solvers who attempt to find good solutions to difficult problems. Surprisingly, we find that teams of randomly selected, intelligent problem solvers outperform teams comprised of the best problem solvers. We prove mathematically why this occurs; the random selection of agents is more diverse. This relationship between diversity and optimality is generic.

Results such as these can influence how we interpret phenomena. They tell us that we should maintain and encourage intellectual diversity, that thermometer measures of intelligence, though possibly correlated with heuristic breadth and depth, sweep important attributes under the table, that universities should be looking for people with the ability to think differently, and that the person who finds the cure or makes the scientific breakthrough need not be the only one who deserves credit. The real breakthrough may have been an overlooked contribution of someone else. Alternatively, when someone makes a huge contribution it may owe as much to that person thinking about the problem differently than it does with that person being intelligent in the traditional sense.

In the second project, Jenna Bednar, a political scientist, and I show how agents adapt cognitive tools that depend upon the ensemble of games that they play. We cast this as a model of "games" theory as opposed to game theory. We provide an explanation for cultural differences: they emerge because societies confront distinct problems and situations, and people adapt their cognitive skills to their environments. In our formulation, the level of cooperation in a culture may be a function of the number of strategic interactions in which people benefit by being cooperative. In two papers published in the American Economic Review, Henrich has found empirical support for this idea.

Finally, in sole authored work, I show how humans choosing economic routes--where and when to shop for food, buy gas, go out to eat, etc.--evolve collections of routes which are efficient but not fully robust. My intuition is that this cannot be true for all systems. Other systems must evolve robustness at the expense of efficiency.

The eventual theory of diversity will provide us with a common understanding of the nature and importance of differences. We may find that only some types of diversity should be embraced. We may find that some systems generate more diversity than we need and that others produce less. We may discover that the types of diversity necessary for efficiency are distinct from those needed for robustness.

At the completion of this project, we will not have developed a complete theory, but we will have made significant progress in that direction. We intend to take what we have learned to produce models and templates that can be used in courses in diversity theory. These courses will have a scientific basis, something lacking in the present undergraduate curricula, management books, and political manifestos that address diversity. We will convene educators and other interested parties in an outreach effort in an effort to change how "diversity" is taught and understood.

In sum, this project will move us from merely recognizing diversity to a deeper understanding of it. Presently, we work to preserve it in our environment, and we require it in our schools. Our business and political leaders speak of harnessing and exploiting it. Yet, we lack the subtle understanding of diversity that can only come from a solid theoretical Foundation. In this project, we intend to begin building that Foundation.