This work provides a game theoretical analysis of the classical idea of a social contract. According to what we might call the Hobbesian justification of the state, coercion is necessary in order to provide people with basic security and to enable them to successfully engage in mutually beneficial cooperation. The establishment and maintenance of a central coercive power, i.e. a state, can therefore be said to be in everyone's interest. The aim of this essay is to examine and evaluate these (...) claims. It is common to interpret the problem of cooperation in a Hobbesian state of nature as a Prisoner's Dilemma game. In this kind of game, each agent prefers that cooperation is brought about, but each also prefers not to cooperate herself, regardless of what others do. Most studies, however, have focused on the prospects for spontaneous cooperation in the 2-player PD. This work focuses instead on the generalized, n-player version of the same game. Invoking an evolutionary game theoretical model, it is argued that the prospects for spontaneous cooperation to emerge in an n-player PD are much worse than in the 2-player case. In order to analyze how the existence of sanctions might affect the prospects for cooperation, a model of a limited sanction system is developed. It is demonstrated that the game that emerges when an n-player PD is modified by a suitable system of sanctions is an n-player version of what Sen has called an Assurance game. It is also demonstrated that in this game, unlike the n-player PD, general cooperation is evolutionarily stable. It is also discussed whether the establishment and maintenance of such a sanction system does itself constitute an n-player PD. It is argued that it does not. (shrink)

National greenhouse-gas accounting should reflect how countries’ policies and behaviours affect global emissions. Actions that contribute to reduced global emissions should be credited, and actions that increase them should be penalized. This is essential if accounting is to serve as accurate guidance for climate policy. Yet this principle is not satisfied by the two most common accounting methods. Production-based accounting used under the Kyoto Protocol does not account for carbon leakage — the phenomenon of countries reducing their domestic emissions by (...) shifting carbon-intensive production abroad1. Consumption-based accounting2,3 does not credit countries for cleaning up their export industries, and it also punishes some types of trade that could contribute to more carbon efficient production worldwide. We propose an improvement to consumption-based carbon accounting that takes technology differences in export sectors into account and thereby tends to more correctly reflect how national policy changes affect total global emissions. We also present empirical results showing how this new measure redraws the global emissions map. (shrink)

According to the so-called “Folk Theorem” for repeated games, stable cooperative relations can be sustained in a Prisoner’s Dilemma if the game is repeated an indefinite number of times. This result depends on the possibility of applying strategies that are based on reciprocity, i.e., strategies that reward cooperation with subsequent cooperation and punish defectionwith subsequent defection. If future interactions are sufficiently important, i.e., if the discount rate is relatively small, each agent may be motivated to cooperate by fear of retaliation (...) in the future. For finite games, however, where the number of plays is known beforehand, there is a backward induction argument showing that rational agents will not be able to achieve cooperation. On behalf of the Hobbesian “Foole”, who cannot see any advantage in cooperation, Gregory Kavka (1983, 1986) has presented an argument that significantly extends the range of the backward induction argument. He shows that, for the backward induction argument to be effective, it is not necessary that the precise number of future interactions be known. It is sufficient that there is a known definite upper bound on the number of interactions. A similar argument is developed by John W. Carroll (1987). We will here question the assumption of a known upper bound. When the assumption is made precise in the way needed for the argument to go through, its apparent plausibility evaporates. We then offer a reformulation of the argument, based on weaker, and more plausible, assumptions. (shrink)

: A popular belief is that the process whereby search engines tailor their search results to individual users, so-called personalization, leads to filter bubbles in the sense of ideologically segregated search results that would tend to reinforce the user’s prior view. Since filter bubbles are thought to be detrimental to society, there have been calls for further legal regulation of search engines beyond the so-called Right to be Forgotten Act. However, the scientific evidence for the filter bubble hypothesis is surprisingly (...) limited. Previous studies of personalization have focused on the extent to which different users get different results lists without taking the content on the webpages into account. Such methods are unsuitable for detecting filter bubbles as such. In this paper, we propose a methodology that takes content differences between webpages into account. In particular, the method involves studying the extent to which users with strong opposing views on an issue receive search results that are correlated content-wise with their personal view. Will users of with strong prior opinion that X is true on average have a larger share of search results that are in favor of X than users with a strong prior opinion that X is false? We illustrate our methodology at work, but also the non-trivial challenges it faces, by a small-scale study of the extent to which Google Search leads to ideological segregation on the issue of man-made climate change. (shrink)