¹ See Diana C. Mutz, ‘Cross-cutting Social Networks: Testing Democratic Theory in Practice’, American Political Science Review, 96 (2002), 111–26; and Diana C. Mutz, Hearing the Other Side: Deliberative Versus Participatory Democracy (New York: Cambridge University Press, 2006).

² For example, see Allan Cigler and Mark R. Joslyn, ‘The Extensiveness of Group Membership and Social Capital: The Impact on Political Tolerance Attitudes’, Political Research Quarterly, 55 (2002), 7–25.

³ For example, see Robert Huckfeldt, Ken’ichi Ikeda and Franz Pappi, ‘Political Expertise, Interdependent Citizens, and the Value Added Problem in Democratic Politics’, Japanese Journal of Political Science, 1 (2000), 171–95.

⁴ John L. Sullivan, James E. Piereson and George E. Marcus, Political Tolerance and American Democracy (Chicago: The University of Chicago Press, 1982).

⁵ Robert Huckfeldt, P. E. Johnson and John D. Sprague, Political Disagreement: The Survival of Diverse Opinions Within Communication Networks (Cambridge: Cambridge University Press, 2004).

⁶ Henry S. Richardson, Democratic Autonomy: Public Reasoning About the Ends of Policy (Oxford: Oxford University Press, 2000).

⁷ Katherine C. Walsh, Talking About Politics: Informal Groups and Social Identity in America (Chicago: University of Chicago, 2003).

⁸ Bernd Simon and Bert Klandermans, ‘Politicized Collective Identity’, American Psychologist, 56 (2001), 319–31.

⁹ Robert D. Putnam, Bowling Alone: The Collapse and Revival of American Community (New York: Simon and Schuster, 2000), p. 22.

¹⁰ Putnam, Bowling Alone, p. 363.

¹¹ This theory is related to the contact hypothesis, which states that contact with outgroup members is useful in decreasing racial/ethnic prejudice and in increasing tolerance. However, we must not downplay the possibly unique nature of racial prejudice, which may be different from simple intolerance. Conceptually, scholarly work on prejudice focuses on the alleviation of racism against specific minorities. By contrast, work on political tolerance focuses on the acceptance of political participation by those who have different opinions from the norm. The latter is an acceptance of the rights of others with the same culture and history – at least in the Japanese case – but having different political goals. This may be different from racial prejudice, which focuses on conflict between those with different, although in some ways overlapping, histories and cultures. Moreover, racial minority groups' demographic characteristics may be distinct, for example with high correlations between income or education and race, whereas it may be different for political tolerance.

¹² George Herbert Mead, Mind, Self and Society (Chicago: University of Chicago Press, 1934).

¹³ Carl Friedrich Graumann, ‘Perspective Setting and Taking in Verbal Interaction’, in R. Dietrich and Carl Friedrich Graumann, eds, Language Processing in Social Context (Amsterdam: North-Holland, 1989), pp. 95–122.

¹⁴ Mutz, Hearing the Other Side.

¹⁵ Huckfeldt, Johnson and Sprague, Political Disagreement.

¹⁶ Katherine C. Walsh, Talking About Politics.

¹⁷ Clarissa R. Hayward, ‘The Difference States Make: Democracy, Identity, and the American City’, American Political Science Review, 97 (2003), 501–14.

¹⁸ Prime Minister’s Commission, Japan’s Goals in the 21st Century (Tokyo, 2000). http://202.232.190.90/jp/21century/report/htmls/index.html (2 December 2006).

¹⁹ Stephen Murphy-Shigematsu, ‘Japan and the Monoethnic Myth,’ MELUS, 18 (1993), 63–80.

²⁰ Sullivan, Piereson and Marcus, Political Tolerance and American Democracy; also see James L. Gibson, ‘Alternative Measures of Political Tolerance: Must Tolerance be “Least-Liked”?’ American Journal of Political Science, 36 (1992), 560–77, for a more in-depth analysis of measures of political tolerance.

²¹ For example, see Toshio Yamagishi and Midori Yamagishi, ‘Trust and Commitment in the United States and Japan’, Motivation and Emotion, 18 (1994), 129–65.

²² Toshio Yamagishi, Structure of Trust (in Japanese) (Tokyo: The University of Tokyo Press, 1998), and Toshio Yamagishi, ‘Trust and Social Intelligence in Japan’, in Frank J. Schwartz and Susan J. Pharr, eds, The State of Civil Society in Japan (Cambridge: Cambridge University Press, 2003), pp. 281–7.

²³ Extremist participation is what is basically measured by the traditional version of political tolerance from Sullivan, Piereson and Marcus, Political Tolerance and American Democracy.

²⁴ Paul Goren, ‘Party Identification and Core Political Values’, American Journal of Political Science, 49 (2005), 881–96, p. 883.

²⁵ Eric M. Uslaner, The Moral Foundations of Trust (Cambridge: Cambridge University Press, 2002).

²⁶ A table of summary statistics is available upon request. The data is available for the first survey at http://ssjda.iss.u-tokyo.ac.jp/abstract/0247a.html, and at http://ssjda.iss.u-tokyo.ac.jp/abstract/0530a.html for the second survey.

²⁷ The number of cases in each model shown below has around a third of the full sample. We tried examining these results with multiple imputation and the results are substantively similar. These results are available upon request.

²⁸ Huckfeldt, Johnson and Sprague, Political Disagreement, p. 34.

²⁹ Mutz, ‘Cross-cutting Social Networks: Testing Democratic Theory in Practice’.

³⁰ Sullivan, Piereson and Marcus, Political Tolerance and American Democracy.

³¹ For example, see Huckfeldt, Johnson and Sprague, Political Disagreement, p. 56.

³² Sometimes there are general issues which are ignored by parties and, if so, these conflicts would not appear as diversity in our measure of network composition.

³³ Some respondents may supply data for fewer than four discussants, but it is important not to delete the information that such respondents provide (e.g., by using list-wise deletion), since data on one-, two-, or three-person networks can prove useful. For respondents with fewer than four discussants, we use 0 as the code for each missing discussant, which has no effect on the total score.

³⁴ We also ran a model in which a dyad of discussants was coded as +1 if the respondent felt that neither of them voted, and −1 if the respondent thought that only one of the dyad voted. The results are substantively similar to those for the original model.

³⁵ Huckfeldt, Johnson and Sprague, Political Disagreement.

³⁶ This list of common associations has been used for various national sample surveys in Japan, including the current dataset. The types of groups are resident association, alumni association, parent–teacher association, farmers’ co-operative, trade association, consumer co-operative, volunteer group, religious group and neighbourhood improvement group.

³⁷ Herbert McClosky, ‘Consensus and Ideology in American Politics’, American Political Science Review, 58 (1964), 361–82.

³⁸ We also tried using the traditional left–right scale, as conservatives are often more intolerant, and the results are similar.

³⁹ Research shows that people who are religious tend to be less tolerant than others (see Jeffery J. Mondak and Mitchell S. Sanders, ‘Tolerance and Intolerance, 1976–1998’, American Journal of Political Science, 47 (2003), 492–502), but we did not take religion into account in our study of Japan. Although almost all Japanese perform ceremonial rituals that have religious origins, scholars generally consider there to be relatively little in the way of religious belief in modern-day Japan (for example, see Mark R. Mullins, Shimazono Susumu and Paul L. Swanson, Religion and Society in Modern Japan: Selected Readings (Fremont, Calif.: Asian Humanities Press, 1993)). Non-belief is so common, in fact, that most Japanese surveys do not ask questions about religion. We believe that the omission of religion did not limit our analysis to any significant extent.

⁴⁰ Mutz, ‘Cross-cutting Social Networks’.

⁴¹ For more on clarify, see Gary King, Michael Tomz and Jason Wittenberg, ‘Making the Most of Statistical Analyses: Improving Interpretation and Presentation’, American Journal of Political Science, 44 (2000), 347–61.