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Diversity and Cooperation


The present dissertation is an exploration of the effect of diversity on social contract formation and the evolution of cooperation. This work stems from the pioneering efforts of economist Arthur Robson, who first explored the role of costless pre-game communication in strategic interactions. When communication is permitted, individuals playing a game can condition their behavior on the signal received from their counterpart. For my purposes, I interpret these signals as racial markers or cultural identifiers, which in turn provides a formal framework to precisely study a number of issues relevant to political and social philosophy.

My first chapter, "Diversity, Tolerance and the Social Contract," starts by formalizing the state of nature as a game in which individuals can either choose to remain in the state of nature or attempt to found a social contract. I assume there exists some natural diversity in the population, and that individuals are pre-disposed to behave cooperatively with those who are more similar to themselves. I uncover an interesting relationship between diversity, tolerance and the social contract. Social contract formation is possible but initially comes with a cost for both diversity and tolerance. That is to say, individuals quickly all adopt the same signal and only behave cooperatively with those who send similar signals. This, however, is not a long-term feature of the population. In the long run, individuals slowly become more tolerant, cooperating with those who are quite dissimilar to themselves. The circle of cooperation expands, and soon all can partake in a thriving social contract.

My second chapter, "Racists and Minorities in Population Games," focuses on the welfare of racial minorities, as well as explores one means of expunging racist attitudes and behaviors from a population. I show that in a wide range of games, minorities are at a distinct disadvantage. Consider the Nash demand game, a canonical bargaining game in which a resource is to be divided between two individuals. I show that in this game, minority status translates into a bargaining disadvantage. In other words, the population tends to settle on an equilibrium in which individuals from theracial majority receive the bulk of the resource. Interestingly, this minority disadvantage is not due to differential abilities or effort, but is instead simply in virtue of the minority's relative size. Second, I consider one means of reducing racist behavior. If individuals are allowed to send a plastic signal that is independent of their fixed racial signal, then individuals tend to condition their behavior on the plastic signal of their counterpart, which in turn facilitates high levels of cooperation.

My final chapter, "The Possibility of Pluralism," explores cooperation and diversity in the context of a liberal pluralistic society. In such a society, many different valid conceptions of the good would exist, and individuals would ideally be tolerant of different moral beliefs and practices. Yet under what conditions is such an arrangement possible? Taking my cue from the political philosopher Gregory Kavka, I investigate how disagreement among individuals with different value systems would be settled. Individuals can either compromise and find some middle ground, or dig their heels in and refuse to concede. Using computer simulations, I identify that conflict is minimized when, among other things, individuals are embedded on a social network and are allowed to employ somewhat sophisticated strategies, such as tit-for-tat.

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