The Politics of Income Inequality: Policy Polarisation, Representation, and the Decline of Social Democracy

Matthew Polacko

Research output: ThesisDoctoral Thesis

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Rising income inequality is one of the greatest challenges facing democracies today. And while income inequality has been steadily increasing in most of the world, the primary means of combating it in the form of redistribution has declined. This thesis investigates the paradox of redistribution and examines in detail the negative effects that inequality can exert on political behaviour, and how these can be mitigated by the actions of political parties. In doing so, it reframes previous approaches to the study of inequality and political behaviour and introduces novel frameworks to better understand the cross-temporal and cross-national dynamics. The thesis takes the format of a compilation comprising four quantitative empirical articles examining the politics of income inequality, via time series cross-sectional analysis, from 1965–2019. In the first two papers, it finds party offerings on redistribution to be a key mechanism moderating inequality and turnout. Paper 1 finds at the aggregate level that income inequality has a negative impact on turnout, especially in depolarised party systems, but as party system polarisation increases the negative impact is mitigated. Paper 2 examines the individual level, finding that higher levels of income inequality significantly reduce turnout, while widening the turnout gap between rich and poor. However, it also finds that when party systems are more polarised in times of inequality, low-income earners are mobilised the most, resulting in a significantly reduced income gap in turnout. The final two papers focus on the decline of social democracy and rise of challenger parties. Paper 3 finds that rightward economic movements of social democratic parties significantly reduce their vote share under higher levels of income inequality, or when they are combined with rightward socio-cultural movements. Paper 4 expands on this work by examining who benefits from this moderation strategy. Ultimately, the thesis sheds greater light onto the issues of political inequality that persist throughout the West and point to a distinct lack of representation in the policy space. The findings demonstrate that the policy choices presented to the electorate substantially matter for parties and for political behaviour, especially so in this age of increasing inequality.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Heath, Oliver, Supervisor
  • Smets, Kaat, Supervisor
Thesis sponsors
Award date1 Oct 2021
Publication statusUnpublished - 16 Sept 2021


  • voting
  • party positions
  • income inequality
  • political behaviour
  • elections
  • social democracy
  • representation

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