Robustness has long been recognized as an important parameter for evaluating game-theoretic results, but talk of ‘robustness’ generally remains vague. What we offer here is a graphic measure for a particular kind of robustness (‘matrix robustness’), using a three-dimensional display of the universe of 2 × 2 game theory. In such a measure specific games appear as specific volumes (Prisoner’s Dilemma, Stag Hunt, etc.), allowing a graphic image of the extent of particular game-theoretic effects in terms of those games. The (...) measure also allows for an easy comparison between different effects in terms of matrix robustness. Here we use the measure to compare the robustness of Tit for Tat’s well-known success in spatialized games (Axelrod, R. (1984). The evolution of cooperation . New York: Basic Books; Grim, P. et al. (1998). The philosophical computer: Exploratory essays in philosophical computer modeling . Cambridge, Mass: MIT Press) with the robustness of a recent game-theoretic model of the contact hypothesis regarding prejudice reduction (Grim et al. 2005. Public Affairs Quarterly, 19 , 95–125). (shrink)

A scientific community can be modeled as a collection of epistemic agents attempting to answer questions, in part by communicating about their hypotheses and results. We can treat the pathways of scientific communication as a network. When we do, it becomes clear that the interaction between the structure of the network and the nature of the question under investigation affects epistemic desiderata, including accuracy and speed to community consensus. Here we build on previous work, both our own and others’, in (...) order to get a firmer grasp on precisely which features of scientific communities interact with which features of scientific questions in order to influence epistemic outcomes. (shrink)

‘The problem with simulations is that they are doomed to succeed.’ So runs a common criticism of simulations—that they can be used to ‘prove’ anything and are thus of little or no scientific value. While this particular objection represents a minority view, especially among those who work with simulations in a scientific context, it raises a difficult question: what standards should we use to differentiate a simulation that fails from one that succeeds? In this paper we build on a structural (...) analysis of simulation developed in previous work to provide an evaluative account of the variety of ways in which simulations do fail. We expand the structural analysis in terms of the relationship between a simulation and its real-world target emphasizing the important role of aspects intended to correspond and also those specifically intended not to correspond to reality. The result is an outline both of the ways in which simulations can fail and the scientific importance of those various forms of failure. (shrink)

In this paper I offer a distinctive epistemic rationale for the liberal practice of constant and ostentatious reason-giving in the political context. Epistemic trust is essential to democratic governance because as citizens we can only make informed decisions by relying on the claims of moral, scientific, and practical authorities around us. Yet rational epistemic trust is also uniquely fragile in the political context in light of both the radical inclusiveness of the relevant epistemic community (i.e., everyone who participates in the (...) political process) and the conflicting interests bound up in policy debate. I argue that liberal justification is a necessary condition for warranted epistemic trust in this context, and therefore a necessary condition for healthy public inquiry about politically significant questions. (shrink)

Philosophers and social scientists have recently turned to game theory and agent-based models to better understand social contract formation. The stag hunt game is an idealization of social contract formation. Using the stag hunt game, we attempt to determine what, if any, barrier diversity is to the formation of an efficient social contract. We uncover a deep connection between tolerance, diversity, and the social contract. We investigate a simple model in which individuals possess salient traits and behave cooperatively when the (...) difference between their trait and the trait of their counterpart is less than their ‘tolerance level’. If traits are fixed and correspond to permanent or semipermanent features of the individual, such as religion or race, social contract formation is a remote possibility. If traits are malleable, social contract formation is possible but comes at the steep cost of diversity and tolerance, that is, individuals are unwilling to cooperate with those much different from themselves. Yet homogeneity and intolerance are not a long-term feature of the population. Over time mutations allow for increasingly tolerant agents to prosper, thereby ushering in trait diversity. In the end, all reap the benefits of cooperation. (shrink)

Cooperation in the prisoner’s dilemma is possible if interactions are sufficiently correlated. We show that when conditions favorable to the evolution of cooperation hold (rb > c) tag-based strategies dominate. Thus, well-meaning interventions aimed at promoting cooperation may succeed but will often lead to in-group favoritism and ethnocentric behavior. Exploring ways that promote cooperation but do not usher in tag-based strategies should be a focal point of future work on the evolution of cooperation.

Cellular automata (henceforth: CA) are discrete, abstract computational systems that have proved useful both as general models of complexity and as more specific representations of non-linear dynamics in a variety of scientific fields. Firstly, CA are (typically) spatially and temporally discrete: they are composed of a finite or denumerable set of homogeneous, simple units, the atoms or cells. At each time unit, the cells instantiate one of a finite set of states. They evolve in parallel at discrete time steps, following (...) state update functions or dynamical transition rules: the update of a cell state obtains by taking into account the states of cells in its local neighborhood (there are, therefore, no actions at a distance). Secondly, CA are abstract, as they can be specified in purely mathematical terms and implemented in physical structures. Thirdly, CA are computational systems: they can compute functions and solve algorithmic problems. Despite functioning in a different way from traditional, Turing machine-like devices, CA with suitable rules can emulate a universal Turing machine, and therefore compute, given Turing's Thesis, anything computable.... (shrink)