¹ See, e.g., Poole, Keith T. and Rosenthal, Howard, Congress: A Political-Economic History of Roll-Call Voting (Oxford: Oxford University Press, 1997)Google Scholar; and McCarty, Nolan, Poole, Keith T. and Rosenthal, Howard, Polarized America: The Dance of Ideology and Unequal Riches (Cambridge, Mass: MIT Press, 2006)Google Scholar.

² See Green, Jane and Hobolt, Sara B., ‘Owning the Issue Agenda: Party Strategies and Vote Choices in British Elections’, Electoral Studies, 27 (2008), 460–476CrossRefGoogle Scholar.

³ See Hetherington, Marc J., ‘Resurgent Mass Partisanship: The Role of Elite Polarization’, American Political Science Review, 95 (2001), 619–631CrossRefGoogle Scholar; Fiorina, Morris P., Abrams, Samuel J. and Pope, Jeremy C., Culture War? The Myth of Polarized America, 2nd edn (New York: Pearson Longman, 2005)Google Scholar; Abramowitz, Alan and Saunders, Kyle L., ‘Is Polarization a Myth?’ Journal of Politics, 70 (2008), 542–555CrossRefGoogle Scholar; Whiteley, Paul and Seyd, Patrick, High-Intensity Participation: The Dynamics of Party Activism in Britain (Ann Arbor: University of Michigan Press, 2002)CrossRefGoogle Scholar; Green, Jane, ‘When Parties and Voters Agree: Valence Issues and Party Competition’, Political Studies, 55 (2007), 629–655CrossRefGoogle Scholar; Layman, Geoffrey C., Carsey, Thomas M. and Horowitz, Juliana, ‘Party Polarization in American Politics: Characteristics, Causes and Consequences’, Annual Review of Political Science, 9 (2006), 83–110CrossRefGoogle Scholar.

⁴ See Ezrow, Lawrence and Xezonakis, Georgios, ‘Citizen Satisfaction with Democracy and Parties’ Policy Offerings: A Cross-National Analysis of Twelve European Party Systems, 1976–2003’, Comparative Political Studies (forthcoming)Google Scholar.

⁵ As we discuss below the evidence from both countries suggests that these trends may be more pronounced with respect to partisan sorting, i.e., changes in the mean policy positions of rival parties’ supporters, than with respect to policy-based polarization, i.e., changes in the extremity of citizens’ policy views.

⁶ On the American electorate, see Claassen, Ryan L. and Highton, Benjamin, ‘Policy Polarization among Party Elites and the Significance of Political Awareness in the Mass Public’, Political Research Quarterly, 62 (2009), 538–551CrossRefGoogle Scholar; Baldassarri, Delia and Gelman, Andrew, ‘Partisans without Constraint: Political Polarization and Trends in American Public Opinion’, American Journal of Sociology, 114 (2008), 408–446CrossRefGoogle Scholar. On the British electorate, see Andersen, Robert, Tilley, James and Heath, Anthony, ‘Political Knowledge and Enlightened Preferences: Party Choice through the Electoral Cycle’, British Journal of Political Science, 35 (2005), 285–302CrossRefGoogle Scholar; Adams, James, Green, Jane and Milazzo, Caitlin, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’ (presented at the annual meeting of the American Political Science Association, Toronto, 2008)Google Scholar.

⁷ While the Liberal Democrats constitute a significant ‘third party’ in Britain, prior to the May 2010 Conservative–Liberal Democratic coalition every post-war British government has been a single-party government.

⁸ See, e.g., Meguid, Bonnie, ‘Competition between Unequals: The Role of Mainstream Party Strategy in Niche Party Success’, American Political Science Review, 99 (2005), 347–360CrossRefGoogle Scholar; Adams, James, Clark, Michael, Ezrow, Lawrence and Glasgow, Garrett, ‘Are Niche Parties Fundamentally Different from Mainstream Parties? The Causes and the Electoral Consequences of Western European Parties’ Policy Shifts, 1976–1998’, American Journal of Political Science, 50 (2006), 513–529CrossRefGoogle Scholar.

⁹ On the types of social cleavages, see Andeweg, Rudy B. and Irwin, Galen A., Governance and Politics of the Netherlands (New York: Palgrave Macmillan, 2002)Google Scholar. On the degree of governmental stability, see Timmermans, Arco I., High Politics in the Low Countries: An Empirical Study of Coalition Agreements in Belgium and the Netherlands (Aldershot, Surrey: Ashgate, 2003)Google Scholar.

¹⁰ These include the Liberal VVD and the Social Liberal D66. In our analyses we focus on the CDA and PvdA because these are the two largest Dutch parties, and they are the pivotal players in coalition government negotiations (see Andeweg and Irwin, Governance and Politics of the Netherlands).

¹¹ See Van Kersbergen, Kees and Krouwel, Andre, ‘A Double-Edged Sword! The Dutch Center-Right and the ‘Foreigners Issue’, Journal of European Public Policy, 15 (2008), 398–414CrossRefGoogle Scholar; Oosterwaal, Annemarije and Totenvlied, Rene, ‘Politics Divided from Society? Three Explanations for Trends in Societal and Political Polarisation in the Netherlands’, West European Politics, 33 (2010), 258–279CrossRefGoogle Scholar.

¹² Adams, Green and Milazzo, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

¹³ In this regard, there is extensive research documenting that citizens in European democracies – all of which feature significantly greater degrees of party-line voting in parliament than does the US Congress – hold quite accurate perceptions of parties’ policy positions. See, e.g., Pierce, Roy, Choosing the Chief: Presidential Elections in France and the United States (Ann Arbor: University of Michigan Press, 1998), pp. 73–74Google Scholar; Stevenson, Randolph T. and Vonnahme, Greg, ‘Executive Selection and the Informed Electorate: How the Rules and Norms Governing Cabinet Formation Impact Citizens’ Knowledge of Politics’ (presented at the annual meeting of the Midwest Political Science Association, Chicago, 2009)Google Scholar.

¹⁴ See, e.g., Bartels, Larry M., Unequal Democracy: The Political Economy of the New Gilded Age (New York: Russell Sage Foundation; and Princeton, N.J.: Princeton University Press, 2008)Google Scholar; Gilens, Martin, ‘Inequality and Democratic Responsiveness’, Public Opinion Quarterly, 69 (2005), 778–796CrossRefGoogle Scholar; Griffin, John and Newman, Brian, ‘Are Voters Better Represented?’ Journal of Politics, 67 (2005), 1206–1227CrossRefGoogle Scholar.

¹⁵ Of course, party policy appeals to affluent and educated voters may confer ancillary benefits, in that members of these groups may disproportionately reward the party with financial contributions and/or with participation in other campaign activities. See, e.g., Brady, Henry, Schlozman, Kay and Verba, Sidney, ‘Redistribution, Polarization, and Medians: Bringing Data to Downsian Puzzles’ (paper presented at the annual meeting of the American Political Science Association, Toronto, 2009)Google Scholar; Adams, James and Ezrow, Lawrence, ‘Who do European Parties Represent? How Western European Parties Represent the Policy Preferences of Opinion Leaders’, Journal of Politics, 71 (2009), 206–223CrossRefGoogle Scholar. Our point is that we should expect that electorates that display more equal responsiveness across subgroups will receive more equal representation from party elites.

¹⁶ See, e.g., Hetherington, ‘Resurgent Mass Partisanship’; Fiorina, Abrams and Pope, Culture War?; Layman, Carsey and Horowitz, ‘Party Polarization in American Politics’; Claassen and Highton, ‘Policy Polarization among Party Elites’.

¹⁷ Hetherington, ‘Resurgent Mass Partisanship’; Baldassarri and Gelman, ‘Partisans without Constraint’.

¹⁸ Andersen, Robert, Heath, Anthony and Sinnott, Richard, ‘Political Knowledge and Electoral Choice’, Journal of Elections, Public Opinion, and Parties, 12 (2002), 11–27CrossRefGoogle Scholar.

¹⁹ Adams, Green, and Milazzo, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

²⁰ We note that by 2001 the Liberal Democrats were arguably to the left of Labour on some social welfare and economic policy issues (see Andersen, Tilley and Heath, ‘Political Knowledge and Enlightened Preferences’). However, in the 2001 and 2005 British Election Studies, survey respondents’ mean placements of Labour were to the left of the Liberal Democrats, i.e., the British electorate continued to perceive Labour and the Conservatives as the two ‘poles’ of the party system.

²¹ Stevenson and Vonnahme, ‘Executive Selection and the Informed Electorate’; Fortunato, David and Stevenson, Randolph T., ‘Perceptions of Partisan Ideologies: The Effect of Coalition Participation’ (presented at the annual meeting of the Midwest Political Science Association, Chicago, 2010)Google Scholar.

²² See Lijphart, Arend, Democracy in Plural Societies: A Comparative Exploration (New Haven, Conn.: Yale University Press, 1977)Google Scholar; Lijphart, Arend, Patterns of Democracy: Governmental Forms and Performance in Thirty-six Countries (New Haven, Conn.: Yale University Press, 1999)Google Scholar.

²³ Over the period 1971–96 the effective number of parliamentary parties in the Netherlands averaged about 4.7, the highest number for any West European democracy except Switzerland. In addition, the Netherlands scores as the most proportional West European electoral system, according to Gallagher's index of disproportionality (see Gallagher, Michael, ‘Proportionality, Disproportionality, and Electoral Systems’, Electoral Studies, 10 (1991), 35–51CrossRefGoogle Scholar). On both points, see Appendix A in Lijphart, Patterns of Democracy.

²⁴ See Andeweg and Irwin, Governance and Politics of the Netherlands.

²⁵ See Andeweg and Irwin, Governance and Politics of the Netherlands; Pellikaan, Huib, van der Meer, Tom and de Lange, Sarah, ‘The Road from a Depolarized to a Centrifugal Democracy’, Acta Politica, 38 (2003), 23–48CrossRefGoogle Scholar; Pellikaan, Huib, de Lange, Sarah and van der Meer, Tom, ‘Fortuyn's Legacy: Party System Change in The Netherlands’, Comparative European Politics, 5 (2007), 282–302CrossRefGoogle Scholar; Oosterwaal and Totenvlied, ‘Politics Divided from Society?’

²⁶ In recent elections there has been increased support for the ideological extremes, represented on the left by the GreenLeft party, which emphasizes environmental protection along with support for social welfare programmes and income redistribution, and on the right by the List Pim Fortuyn Party for Freedom which has advocated strong nationalist and anti-immigrant policies, see, e.g., Andeweg and Irwin, Governance and Politics of the Netherlands; Mair, Peter, ‘Electoral Volatility and the Dutch Party System: A Comparative Perspective’, Acta Politica, 43 (2008), 235–253CrossRefGoogle Scholar. However, the growth of these parties – which we discuss below – occurred largely after the period of this study.

²⁷ Martin Lipset, Seymour and Rokkan, Stein, ‘Cleavage Structures, Party Systems, Voter Alignments: An Introduction’, in Seymour Martin Lipset and Stein Rokkan, eds., Party Systems and Voter Alignments: Cross-National Perspectives (New York: The Free Press, 1967), pp. 1–64Google Scholar; Andeweg and Irwin, Governance and Politics of the Netherlands, p. 491.

²⁸ See Mair, ‘Electoral Volatility and the Dutch Party System’.

²⁹ See Timmermans, Arco I., High Politics in the Low Countries: An Empirical Study of Coalition Agreements in Belgium and the Netherlands (Aldershot, Surrey: Ashgate, 2003)Google Scholar.

³⁰ Timmermans, High Politics in the Low Countries.

³¹ Although the CDA did not vocally mobilize on this issue like the small Christian right, see, e.g., Pellikaan, van der Meer and de Lange, ‘The Road from a Depolarized to a Centrifugal Democracy’.

³² Rochon, Thomas R., The Netherlands: Negotiating Sovereignty in an Interdependent World (Boulder, Colo.: Westview, 1999)Google Scholar.

³³ Timmermans, High Politics in the Low Countries.

³⁴ Rochon, The Netherlands.

³⁵ In the words of the party leader, Prime Minister Wim Kok, the PvdA needed to ‘shake off its ideological feathers’ to attract moderate voters (quoted in Andeweg and Irwin, Governance and Politics of the Netherlands). In addition, the party's moderation on economic and social welfare issues was driven by coalition-based considerations: namely, that the PvdA's policy moderation would make it an acceptable partner in a ‘purple’ coalition with the centre-right VVD. In the event, the PvdA's moderating policy shifts accomplished both objectives in that the party increased its support among moderate voters and also engineered the ‘impossible’ Purple Coalition with the PvdA in 1994 and 1998. On these points, see Rochon, The Netherlands.

³⁶ See Pellikaan, van der Meer and de Lange, ‘The Road from a Depolarized to a Centrifugal Democracy’; Sara Hobolt and Catherine de Vries, ‘Issue Entrepreneurship and the Dynamics of Multiparty Competition’ (presented at the annual meeting of the Midwest Political Science Association, Chicago, 2010).

³⁷ Of course, there were additional salient issues on the Dutch political agenda at various points during the 1980s and 1990s, such as the placement of cruise missiles on Dutch soil during the 1980s, but unfortunately the Dutch Parliamentary Election Studies from this period only consistently included the four scales listed above.

³⁸ We have reversed the policy scales so that higher numbers denote a more conservative position, so that they are consistent with the Left–Right scale. The Appendix to be found on the Cambridge Journals Online website presents the texts of the policy scale questions.

³⁹ Adams, Green and Milazzo, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

⁴⁰ See, e.g., Keith Poole and Howard Rosenthal, Congress: A Political-Economic History of Roll-Call Voting.

⁴¹ Converse, Philip E., ‘The Nature of Belief Systems in Mass Publics’, in David E. Apter, ed., Ideology and Discontent (New York: The Free Press, 1964)Google Scholar.

⁴² Baldassarri and Gelman, ‘Partisans without Constraint’, pp. 418–19.

⁴³ See, e.g., Carmines, Edward G. and Stimson, James A., Issue Evolution: Race and the Transformation of American Politics (Princeton, N.J.: Princeton University Press, 1989)Google Scholar; Hetherington, Marc, ‘Review Article: Putting Polarization in Perspective’, British Journal of Political Science, 39 (2009), 413–448CrossRefGoogle Scholar; Levendusky, Matthew S., ‘The Microfoundations of Mass Polarization’, Political Analysis, 17 (2009), 162–176CrossRefGoogle Scholar. We note that this partisan sorting may occur either because citizens shift their partisan loyalties to match their policy attitudes and/or because citizens update their policy attitudes to fit their party identification, see, e.g., Carsey, Thomas M. and Layman, Geoffrey C., ‘Changing Sides or Changing Minds? Party Identification and Policy Preferences in the U.S. Electorate’, American Journal of Political Science, 50 (2006), 464–477CrossRefGoogle Scholar; Milazzo, Caitlin, Adams, James and Green, Jane, ‘Are Voter Decision Rules Endogenous to Parties’ Policy Strategies? A Model with Applications to Elite Depolarization in Post-Thatcher Britain’, Journal of Politics (forthcoming)Google Scholar.

⁴⁴ Adams, James, Green, Jane and Milazzo, Caitlin, ‘Has the British Public Depolarized along with Political Elites? An American Perspective on British Public Opinion’, Comparative Political Studies (forthcoming)Google Scholar.

⁴⁵ Party identification categories were computed by using the party to which an individual said they were an adherent, along with the reply to a follow-up question for respondents who stated that they were not adherents of any party, which asked whether there was a party to which the respondent was primarily attracted. (The texts of both questions are reported in the Appendix available at Cambridge University Press Journals Online.) Respondents who named a party in response to either question were classified as partisans of that party. We note that we recomputed the means reported in Table 4 using a stricter definition of partisanship, which omitted the follow-up question, and these computations supported substantive conclusions that were identical to those we report below.

⁴⁶ We performed additional computations that bear on partisan sorting in the Dutch electorate by computing the correlations between DPES respondents’ self-placements on the policy scales and their net CDA–PvdA propensity to vote, defined as the difference between the respondent's reported propensity to vote for the CDA and her reported propensity to vote for the PvdA. (This measure was based on the respondent's answers to the following question: ‘Would you indicate for each party how probable it is that you will ever vote for that party?’) We found that the correlations between DPES respondents’ self-placements on the policy scales and their propensities to vote for the CDA versus the PvdA diminished sharply between 1986 and 1998. These computations thereby support the same substantive conclusion as the analyses reported in Table 4.

⁴⁷ See, e.g., Steenbergen, Marco, Edwards, Erica E. and de Vries, Catherine, ‘Who Is Cueing Whom? Mass-Elite Linkages and the Future of European Integration’, European Union Politics, 8 (2007), 13–35CrossRefGoogle Scholar; Carsey and Layman, ‘Changing Sides or Changing Minds?’; ‘ Nagel, Jack and Wlezien, Christopher, ‘Centre-party Strength and Major-party Divergence in Britain, 1945–2005’, British Journal of Political Science, 40 (2010), 279–304CrossRefGoogle Scholar; Highton, Benjamin and Kam, Cindy, ‘The Long-Term Dynamics of Partisanship and Issue Orientations’, Journal of Politics, 73 (2011), 202–215CrossRefGoogle Scholar; Dancey, Logan and Goren, Paul, ‘Party Identification, Issue Attitudes, and the Dynamics of Political Debate’, American Journal of Political Science, 54 (2010), 686–699CrossRefGoogle Scholar. This research suggests that the extent to which citizens react to parties’ policy positions by updating their own policy beliefs (policy cueing), as opposed to updating their party attachments (party switching), varies with individual-level characteristics such as political knowledge and engagement, along with system-level characteristics such as the degree of party polarization on the focal policy dimension along with the intensity of media coverage on this dimension. For our purposes the important point is that to our knowledge all extant studies of this issue conclude that citizens do indeed react to their perceptions of party policy positions by updating their own policy beliefs and/or their party attachments.

⁴⁸ For comparative studies of whether parties adjust their policy positions in response to public opinion, see, e.g., Ezrow, Lawrence, ‘The Variance Matters: How Party Systems Represent the Preferences of Voters’, Journal of Politics, 69 (2007), 182–192CrossRefGoogle Scholar; Adams, James, Clark, Michael, Ezrow, Lawrence and Glasgow, Garrett, ‘Understanding Change and Stability in Party Ideologies: Do Parties Respond to Public Opinion or to Past Election Results?’ British Journal of Political Science, 34 (2004), 589–610CrossRefGoogle Scholar. For more specific studies on the Dutch case, see for example Aarts, Kees and Thomassen, Jacques, ‘Dutch Voters and the Changing Party Space 1989-2006’, Acta Politica, 43 (2008), 203–234CrossRefGoogle Scholar; Oosterwaal and Totenvlied, ‘Politics Divided from Society?’

⁴⁹ Our focus on these subgroups is in line with previous research that analyses how mass–elite policy linkages are mediated by citizens’ levels of political knowledge, education and income (see, e.g., Bartels, Unequal Democracy; Gilens, ‘Inequality and Democratic Responsiveness’; Adams and Ezrow, ‘Who do European Parties Represent?’). We note that there is (modest) overlap between these individual-level characteristics in that the correlation between these measures ranges from 0.2 (between income and political interest) to 0.4 (between knowledge and political interest). From our perspective, the key question is not whether Dutch citizens’ political knowledge correlates with other characteristics such as education, income and political interest, but whether citizens with high levels of political knowledge, education and income have similar perceptions of (and reactions to) elites’ policy shifts as do citizens with lower levels of knowledge, education, income and political interest. The analyses we present below suggest that this is indeed the case.

⁵⁰ The political knowledge quiz in the DPES consisted of twelve questions. Respondents were presented with pictures of four senior political party members and asked to identify their name, party identification, and function within that party. In 1998, for example, individuals were shown pictures of Jaques Wallage, leader of the PvdA faction in parliament; Thom der Graaf, leader of the D66 faction in parliament; Annemarie Jorritsma, a member of the VVD and minister for transport; and Piet Bukman, member of the CDA and chairman of the Second Chamber. Respondents were coded ‘high’ on political knowledge if they provided more correct answers than the average respondent in the survey, and ‘low’ otherwise.

⁵¹ For simplicity, Figure 1 presents subconstituency-based perceptions on the Left–Right scale only; however, the patterns on the policy scales relating to income inequality, nuclear power and euthanasia support identical substantive conclusions.

⁵² The DPES uses an index of political interest developed from four questions, including: how frequently the respondent reads about national news (‘nearly always’ to ‘does not read paper’); how often the respondent discusses national news (‘joins conversation’ to ‘does not listen/not interested’), how often the respondent reads about foreign news (‘nearly always’ to ‘does not read paper’), and the respondent's reported interest in politics (‘very interested’ to ‘not interested’). Respondents were classified as high interest if they scored above the mean on this political interest index, and were classified as low interest if they scored below the mean.

⁵³ Adams, Green and Milazzo, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

⁵⁴ Hetherington, ‘Resurgent Mass Partisanship’.

⁵⁵ See, e.g., Andersen, Heath, and Sinnott, ‘Political Knowledge and Electoral Choice’; Clark, Michael, ‘Valence and Electoral Outcomes in Western Europe 1976–1998’, Electoral Studies, 28 (2009), 111–122CrossRefGoogle Scholar; Abney, Ronnie, Adams, James, Clark, Michael, Easton, Malcolm, Ezrow, Lawrence, Neundorf, Anja and Kosmidis, Spyros, ‘When Does Valence Matter? On Heightened Valence Effects for Governing Parties during Election Campaigns’, Party Politics (forthcoming)Google Scholar.

⁵⁶ The patterns on the policy scales relating to income inequality, nuclear power and euthanasia support the same substantive conclusions as the patterns we report here on Left–Right ideology.

⁵⁷ As discussed above, the high-engagement subgroup consists of DPES respondents who possessed at least three of the following attributes: they scored above average on the political knowledge quiz; they scored above average on the political interest index; they were above average in education; they were above average in income. The low-engagement group consists of respondents who were below the mean on at least three of these attributes.

⁵⁸ Baldassarri and Gelman, ‘Partisans without Constraint’.

⁵⁹ As discussed above, the six issue pairs are: Left–Right/income inequality; Left–Right/euthanasia; Left–Right/nuclear power; income inequality/euthanasia; income inequality/nuclear power; euthanasia/nuclear power.

⁶⁰ Adams, Green and Milazzo, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

⁶¹ We note that the partisan self-placement patterns on the three policy scales support identical substantive conclusions as the patterns we report here on Left–Right ideology.

⁶² Adams, Green and Milazzo’, ‘Which Voting Subconstituencies Have Reacted to Elite Depolarization in Britain?’

⁶³ See, e.g., Hetherington, ‘Resurgent Mass Partisanship’; Baldassarri and Gelman, ‘Partisans without Constraint’.

⁶⁴ See, e.g., Bartels, Unequal Democracy; Gilens, ‘Inequality and Democratic Responsiveness’.