This presidential lecture argues that agent-based modeling contributes to the development of theories of social change. Although social change has been an attractive topic to many sociologists, they have mainly focused on the analysis of social change at the macro level with little attention to the micro-macro linkage. Takatoshi Imada's theory of self-organization, as an exceptional case, clearly studies the linkage, but even his theory does not provide a clear analysis of the transition from the micro to the macro level. Agent-based modeling, I would argue, clearly analyzes the transition. However, we need to clarify the concept of role when applying the method to the study of structural change, which has been the main theme in theories of social change. Recently, a few studies of formalizing the concept of role have been published, so agent-based modeling will contribute to the development of theories of social change by combining its ideas and the studies.

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Twenty years have passed since quantitative sociologists launched life course research in the mid-1980s. A large number of life course researches are roughly classified into two types in terms of characteristics of data set. The first type is studies based on surveys that followed up life histories of unique groups. This paper describes the life history data of three famous studies: Children of the Great Depression, Freedom Summer, and Crime in the Making. The second type is studies based on standardized life history surveys that allow us to compare birth cohorts. The German retrospective life history study, which started in 1981 and completed in 2004, is a typical example. This paper introduces research methods that the German life history study has developed, and discusses results of the current study that analyzed quantitative life histories of German women and men born in 1964 and in 1971. In order to develop quantitative life course studies furthermore, it is necessary to conduct comparative studies hat examine the influence of contemporary social changes on life course. Path dependency and reconstructing individualism are two key concepts to clarify the current state of the post-war Japanese life course regime from a comparative perspective

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Quantitative sociological researches in Japan have not tried to apply the simultaneous analysis employing interaction variables but have used the comparison of separated analyses among sub-samples by a model with the same independent variables, when the research task accompanies multiple-comparison. However, the comparison of separated analyses tends to be influenced by subjective eyeballing judgment about differences among sub-samples. How to carry out multiple-comparison by the simultaneous analysis using logit models on educational achievement was examined and illustrated. As the simultaneous analysis model concerning educational attainment, ordered logit model which is more parsimonious than transitional model and multinominal logit model in terms of the number of parameters is advantageous to multiple-comparison. Efforts to explore the possibility of simultaneous analysis should be required for not only logit models but other kinds of models.

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This paper explores the effects of solidarity group upon collective dilemma using game theory, and investigates the conditions and mechanism on which this dilemma is resolved. This dilemmatic situation means that rational and self-interested individuals in a group may not achieve their common goal even if all of them would be better off. Although social theories based on rationality pay attention to solidarity group, it is not enough to capture its effect through micro-macro level linkage. This study formulates such a problematic situation as a game theoretic model called an “n-person chicken game”. Surveying previous Nash equilibrium analysis, this paper analyzes the “n-person chicken game” using the strong Nash equilibrium that considers not only individual deviations but also the possibility of coalitional deviations. The result implies that the coalitional corporations achieved by communication between members of solidarity group resolve the dilemma. This implication supports the importance of solidarity group emphasized by Resource Mobilization Theory.

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The purpose of this paper is to lay theoretical foundations of social motives in dyad model from the view point of altruism and egalitarianism. I show following two findings. First, I show some criteria for classifying four approaches to social motives that were introduced by Umino. Second, by using the plane of altruism and egalitarianism I put in order various social motives. Then I clarify mutual relations among typical 13 social motives: for example “maxmin” is the weak type of altruistic and egalitarian motive and strong type of it is “a pang of conscience”.

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On the economic background of the People's Rights Movement, there has been contradictory between the “Agriculture Commercial Economy Theory” and the “Middle-zone Theory”. This paper aims to resolve this contradictory by combining the fluctuation of land tax and the local characteristics of the movement. Assuming that the agriculture in the earlier stage of Meiji period was a transitional economy, we built a model to describe the dynamic process of the land tax fluctuation. Furthermore, using the land tax data from 1875 till 1887, we deduced the values of parameters α and θ, which measuring the speed and the friction cost of the capital transfer respectively. As a result, the “Middle-zone Theory” is more reasonable if we focus on the intensified events. However, the “Agriculture Commercial Economy Theory” is more persuasive if we observe the movement from the whole picture.

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The purpose of this paper is to characterize the Talmud solution in the bankruptcy game by using the core of the fuzzy valued TU game. It has the feature that the Talmud solution is an advantageous distribution rule for the player who is lending the little capital from a relative viewpoint. Additionally, it is clear that the distribution rule in Mishnah is the only stable method with no bias from viewpoint of satisfaction.

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Social influence is a feature indicating the degree to which a member is remarked upon in a society or a community. Social influence could also be regarded as the degree to which a member is given priority for the distribution of social resources through social evaluation and its results. An ideal environment where individuals were able to decide which of all members warranted attention is impossible in actual environments because of the combinatory explosion. As a result, in actual environments, given the sensitivity of the initial conditions of a complex system, a state of local minimum where existing values (abilities) and social influence correspond becomes rarer and rarer. When this happens, we find members where social influence does not match existing values (latent abilities), members who, in spite of having little existing value, yet possess social influence (arrogance), and other conditions that result in an implicit social unfairness and ineffective communication, which, from the perspective of the entire society/ community, represents a great loss. In this paper, we construct a model of the interdependent relationships of the unique characteristics of social influence and it is shown that in ideal environments a member's existing values (abilities) and social influence correctly correspond to one another whereas on the other hand, in actual environments, the problems of latent abilities and arrogance occur. Based on that, this research proposes new models of protocol for communication controls to solve such problems and testifies to their effectiveness. Some of the models are proven to be effective for an efficient and fair society by simulations, so experimentation within an online community was conducted to prove its effectiveness in an actual environment of a online bulletin board.

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Recent research (Flache 1996; Flache and Macy 1996) suggests a “weakness of strong ties.” Cohesive social networks may undermine group solidarity, rather than sustain it. In the original analysis, simulations showed that adaptive actors learn cooperation in bilateral exchanges faster than cooperation in more complex group exchanges, favoring ties at the expense of the common good. This article uses game theory to demonstrate that cognitive simplicity is not a scope condition for the result. The game theoretical analysis identifies a new condition for the failure of group solidarity in a cohesive group. Task uncertainty may make rational cooperation increasingly inefficient in common good production. Accordingly, rational actors may increasingly sacrifice benefits from common good production in order to maintain social ties, as their dependence on peer approval rises.

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[in Japanese]

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[in Japanese]

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