A computational model of spatial politics: Hotelling-Downs model as statistical physics

Fuente: arXiv
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Main Authors: Campbell, Christopher, Ackland, Graeme J.
Format: Preprint
Published: 2026
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author Campbell, Christopher
Ackland, Graeme J.
author_facet Campbell, Christopher
Ackland, Graeme J.
contents The Hotelling-Downs model considers parties changing policy to maximise their vote-share. Where policy position lies on a left-right axis, it describes a tendency for political parties to move towards centrist platforms. This is in contrast with widely observed political polarisation. We extend the model to two dimensions, with many parties and with single and multiple-peaked voter distribution. We find that a two party system reduces polarisation, even if voters are polarised with a bimodal distribution. By contrast, multiparty systems induce polarisation, even when most voters favour moderate position. We model the effect of turnout and activists as influences on the parties, showing that this results in more polarisation, even in a two-party system. This suggests that polarisation of parties can be driven by abstention, intra-party politics and turnout on the extremes. In the two-party case, the winning party's positions are more moderate than the views of their supporters but better representative of the electorate as a whole. With polarisation, individual voters are better able to find a party which represents their views, but the government (winning part or coalition) is less representative of the population, even when the population has a clear consensus on all issues.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09784
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A computational model of spatial politics: Hotelling-Downs model as statistical physics
Campbell, Christopher
Ackland, Graeme J.
Physics and Society
Adaptation and Self-Organizing Systems
The Hotelling-Downs model considers parties changing policy to maximise their vote-share. Where policy position lies on a left-right axis, it describes a tendency for political parties to move towards centrist platforms. This is in contrast with widely observed political polarisation. We extend the model to two dimensions, with many parties and with single and multiple-peaked voter distribution. We find that a two party system reduces polarisation, even if voters are polarised with a bimodal distribution. By contrast, multiparty systems induce polarisation, even when most voters favour moderate position. We model the effect of turnout and activists as influences on the parties, showing that this results in more polarisation, even in a two-party system. This suggests that polarisation of parties can be driven by abstention, intra-party politics and turnout on the extremes. In the two-party case, the winning party's positions are more moderate than the views of their supporters but better representative of the electorate as a whole. With polarisation, individual voters are better able to find a party which represents their views, but the government (winning part or coalition) is less representative of the population, even when the population has a clear consensus on all issues.
title A computational model of spatial politics: Hotelling-Downs model as statistical physics
topic Physics and Society
Adaptation and Self-Organizing Systems
url https://arxiv.org/abs/2605.09784