¹ Downs, Anthony, An Economic Theory of Democracy (New York: Harper, 1957), pp. 115–118Google Scholar.

² Downs, , Economic Theory, pp. 122–7Google Scholar.

³ Barry, Brian, Sociologists, Economists and Democracy (London: Collier Macmillan, 1979), pp. 118–125Google Scholar.

⁴ McDonald, Michael D., Mendes, Silvia and Budge, Ian, ‘What Are Elections For?’ British Journal of Political Science, 34 (2004), 1–26CrossRefGoogle Scholar.

⁵ Downs, , Economic Theory, pp. 96–111Google Scholar.

⁶ For a critical evaluation, see Barry, Sociologists, Economists and Democracy. For formal modelling, see, for example, Endow, James M. and Hinich, Melvin J., The Spatial Theory of Voting (Cambridge: Cambridge University Press, 1984)Google Scholar.

⁷ The activities of the MRG-CMP and the data produced by them are extensively documented in Budge, Ian, Klingemann, H-D., Volkens, Andrea, Bara, Judith, Tanenbaum, Eric et al. , Mapping Policy Preferences (Oxford: Oxford University Press, 2001)Google Scholar, and Klingemann, H-D., Volkens, Andrea, Bara, Judith, Budge, Ian and McDonald, Michael D., Mapping Policy Preferences II (Oxford: Oxford University Press, 2006)Google Scholar. Both books are sold with attached CDs containing documentation and data. As we use these for our own analysis, they are described in detail below.

⁸ The Manifesto dataset and the construction of the left–right scale, which we use in our own analysis, are described in more detail in our data section below. The claim of the scale to provide the best summary representation of public and party policy is buttressed by the spontaneous emergence of a powerful leading left–right dimension from factor analyses of the Manifesto data reported in Budge, Ian, Robertson, David and Hearl, Derek J., eds, Ideology, Strategy and Party Movement (Cambridge: Cambridge University Press [1987], 2008)Google Scholar, and Gabel, Matthew J. and Huber, John D., ‘Putting Parties in Their Place’, American Journal of Political Science, 44 (2000), pp. 94–103CrossRefGoogle Scholar.

⁹ Similar patterns are found in other countries as reported in the two Mapping Policy Preferences volumes. However, as they mostly have multiparty systems, non-convergence would have been expected from Downs’s arguments about this case in the Economic Theory, pp. 122–5 (see Fig. 2).

¹⁰ The studies are listed in the notes to Table 1. The Eurobarometer survey, sponsored by the EU in its member and candidate states, includes a left–right self-placement scale for electors.

¹¹ The rules are cast in a prescriptive form on the basis of the observed correlations between opinion shifts and party changes of position in at least eight European countries.

¹² For empirical evidence on this point, see Adams, James, Clark, Michael, Ezrow, Lawrence and Glasgow, Garrett, ‘Are Niche Parties Fundamentally Different from Mainstream Parties? The Causes and Electoral Consequences of Western European Parties’ Policy Shifts, 1976–1998’, American Journal of Political Science, 50 (2006), 513–529CrossRefGoogle Scholar.

¹³ For further analyses which support this conclusion, see McDonald, Michael D. and Budge, Ian, Elections, Parties, Democracy: Conferring the Median Mandate (Oxford: Oxford University Press, 2005)CrossRefGoogle Scholar.

¹⁴ Budge, Ian, ‘A New Spatial Theory of Party Competition: Uncertainty, Ideology and Policy Equilibria Viewed Comparatively and Temporarily’, British Journal of Political Science, 24 (1994), 443–468CrossRefGoogle Scholar.

¹⁵ For a more extended analysis of ‘wandering’ and ‘leapfrogging’, see McDonald, M. D. and Budge, Ian, Elections, Parties, Democracy: Conferring the Median Mandate (Oxford: Oxford University Press, 2005), pp. 62–73CrossRefGoogle Scholar: Klingemann, et al. , Mapping Policy Preferences II, pp. 67–74Google Scholar.

¹⁶ Budge, , ‘A New Spatial Theory’, p. 461Google Scholar.

¹⁷ Cf. Wlezien’s ‘thermostatic’ model. See also Wlezien, Christopher, ‘Dynamics of Representation: The Case of US Spending on Defence’, British Journal of Political Science, 26 (1996), 81–103CrossRefGoogle Scholar.

¹⁸ Robertson, David, A Theory of Party Competition (London: Wiley, 1976)Google Scholar.

¹⁹ Of course, some of the other rules fit almost as well.

²⁰ Laver, Michael‘Policy and the Dynamics of Party Competition’, American Political Science Review, 99 (2005), 263–281CrossRefGoogle Scholar, The ‘New Spatial Theory’ is not, however, cited in his discussion.

²¹ One should note here the same difficulty as occurred with the NST – parties are characterized by the decision rule which fits them best, in some sense, but it is plausible that other rules fit them almost as well. This provides some grounds for thinking that the rules are not as independent of each other as they appear. We follow up this point below.

²² Tavits, Margit, ‘Principle vs Pragmatism: Policy Shifts and Political Competition’, American Journal of Political Science, 51 (2007), pp. 151–165CrossRefGoogle Scholar. For a compelling spatial analysis of Democratic and Republican policy movements on economic and social dimensions in the United States since 1896, see Miller, Gary and Schofield, Norman, ‘Activists and Partisan Realignment in the United States’, American Political Science Review, 97 (2003), 245–260CrossRefGoogle Scholar.

²³ Money, Jeanette and Andrews, Josephine, ‘Parties’ Electoral Strategies: An Empirical Analysis’ (unpublished paper, Department of Political Science, University of California, Davis, 2007)Google Scholar.

²⁴ Adams, James, ‘A Theory of Spatial Competition with Biased Voters’, British Journal of Political Science, 31 (2001), 210–223CrossRefGoogle Scholar.

²⁵ Apart from anything else, some electors will not vote.

²⁶ Weak correlations in the 0.20 to 0.40 range have been attained only by controlling for other aspects of the data which seem to characterize them more powerfully, such as reactions to past vote and strong alternation of policy between left and right. The actual findings are sometimes contradictory and often explained on ideological grounds internal to parties rather than purely external vote-seeking ones – (‘niche’ parties, for example).

²⁷ For a formal proof of the disutility of being in office and pursuing repugnant policies, see Budge, Ian and Farlie, Dennis, Voting and Party Competition (London: Wiley, 1977), pp. 150–160Google Scholar.

²⁸ Harmel, Robert and Tan, Alexander C., ‘Party Actors and Party Change: Does Factional Dominance Matter?’ European Journal of Political Research, 42 (2003), 409–424CrossRefGoogle Scholar; Giannetti, Daniela and Benoit, Kenneth, eds, Intra Party Politics and Coalition Governments (London: Routledge, 2008)Google Scholar.

²⁹ Cf. Lipset and Rokkan’s observation in their study of West European party systems that the party families in 1964 looked largely as they did in 1918 ( Lipset, S. M. and Rokkan, Stein, Party Systems and Voter Alignments (New York: Free Press, 1967)Google Scholar – substantiated in a careful historical study by Bartolini, Stefano and Mair, Peter, Identity, Competition and Electoral Availability: The Stabilization of European Electorates 1885–1986 (Cambridge: Cambridge University Press, 1990)Google Scholar).

³⁰ See, for example, the review article by Nanestad, Peter and Paldam, Martin, ‘The Cost of Ruling’, in Han Dorussen and Michael Taylor, eds, Economic Voting (London: Routledge, 2002), pp. 17–44Google Scholar.

³¹ We should, however, stress again that there is no unified party decision maker postulated as enforcing these moves, which are rather outcomes of a process of factional alternation.

³² Budge, et al. , Mapping Policy Preferences, pp. 41–7Google Scholar.

³³ McDonald, M. D. and Budge, Ian, Elections, Parties, Democracy: Conferring the Median Mandate (Oxford: Oxford University Press, 2005), p. 21CrossRefGoogle Scholar.

³⁴ Budge, et al. , Mapping Policy Preferences; Klingemann et al., Mapping Policy Preferencees IIGoogle Scholar. Both publications are sold with a CD containing all the data we use here.

³⁵ The MRG-CMP counted the (quasi-) sentences of all the significant parties’ programmes in each post-war election, first for twenty countries and subsequently for fifty-four (including the twenty-five we focus on here) into one and only one of fifty-six policy categories. ‘A quasi sentence is defined as an argument or phrase which is the verbal expression of one idea or meaning. It is often marked off in a text by commas or (semi) colons’ (Klingemann et al., Mapping Policy Preferences II, p. xxiii). To create the left–right scale, ‘left’ policy categories were identified on theoretical grounds and the percentaged quasi-sentences falling into them added up. ‘Right’ categories were similarly identified and the percentages added up. The sum of the left percentages were then subtracted from the sum of the right percentages to give the overall additive scale running from −100 (left) to +100 (right). As the summed percentages are based on the total number of (quasi-) sentences in a manifesto, scores can also be affected by the number of non left–right references in the document. In this sense, the left–right scale reflects policy tendencies across the whole document. ‘Left’ categories broadly cover government intervention, welfare and peace, while right ones are concerned with freedom, traditional values and military strength. Each party programme can thus be given a single left–right score and movement to the left or right estimated by the difference between programme scores in successive elections.

³⁶ Tavits, M., Principle vs Pragmatism, p. 156; Klingemann et al., Mapping Policy Preferences II, p. 105Google Scholar.

³⁷ Another consideration for choosing the American Republicans is that readers will be reasonably familiar with this example.

³⁸ The website address is http://privatewww.essex.ac.uk/~ezrow.

³⁹ The countries included in the analyses are Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Japan, Luxembourg, the Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom and the United States.

⁴⁰ The left–right estimates of parties’ positions remained totally unchanged for 125 inter-election shifts in the analysis.

⁴¹ For these analyses, Australia and France are classified with the plurality systems (even though they have essentially majority-based rules).

⁴² The test thus takes on the statistical form of Λ, in terms of the formula: Λ_b = (Number of errors under alternative form of prediction – Number of errors under rules from integrated theory)/Number of errors under alternative form of prediction. The value varies between 0 and 1.00.

⁴³ Error in this context means that a ‘true’ leftward shift has been inaccurately measured or coded as a rightward shift in the data. We assume – for this limited set of analyses – that these errors are balanced over the 1,737 party-policy shifts analysed.

⁴⁴ However, within a context of increasing interest in their explanatory potential, cf. Aldrich’s use of activist factions to explain non-convergence under the Downsian two-party model ( Aldrich, John, ‘A Downsian Spatial Model with Party Activism’, American Political Science Review, 77 (1983), 974–990CrossRefGoogle Scholar): also Harmel and Tan, ‘Party Actors and Party Change’; and Gianetti and Benoit, Intra Party Politics.