著者

土屋 大洋

出版者

一般財団法人 日本国際政治学会

雑誌

国際政治 (ISSN:04542215)

巻号頁・発行日

vol.2009, no.155, pp.155_109-125, 2009

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This paper analyzes political connections using a method based on network theory. Recent developments in network theory, which have been accelerated by advances in computers and data collection, can be applied to various research areas including physics, information society studies, sociology and other social sciences.<br>This paper uses network theory to analyze networks among U.S. senators who submitted bills related to Japan in the 109th Congress, focusing on cosponsorship of bills. Senators sometimes submit bills with other senators to make them more prospective, to gain more attentions, or just to deal with political bargains. This paper assumes that senators who co-submit bills more often have tighter connections and organize wider networks. Although it is difficult for an outsider to know who has what kinds of connections with whom in politics, it is easier to track who acted with whom in co-sponsoring bills in Congress.<br>The results of the analysis show that Japan-related bills were led by influential leaders in the senate such as Barack Obama, Joe Biden, Hillary Clinton and Joseph Lieberman, who played important roles in the 2008 Presidential election. They were active in submitting and co-sponsoring bills and had higher scores in network indexes such as degree, between centrality, and closeness centrality. This implies two possible hypotheses. First, those influential leaders themselves were interested in Japan-related issues. Second, no specific senators were interested in the issues and that is why the influential senators seemed to be leading. These hypotheses should be tested in combination with other analytical methods.<br>Network analysis has three advantages. First, it focuses more on relationships among actors instead of looking at the characters of individual actors. Most of conventional analysis methods look at who actors are and what they do. In contrast, network analysis focuses on who is connected to whom and how. Second, the development of network analysis and data collection could give us alternative perspectives and new results based on large amounts of data. Third, network analysis could be used not only for proving hypotheses, but also for finding new ones.<br>Network analysis can be applied both to case studies in international relations and to enriching the theories of international relations. Actors in international relations vary from nation states (or governments), multi-national or global corporations, non-profit or non-state organizations, and even to individuals. Network analysis tells how they are connected and how they are interacting. It should reveal more dynamic relations rather than stable structures.