Political parties and interest groups play a vital role in incorporating societal interests into democratic decision‐making. Therefore, explaining the nature and variation in the relationship between them will advance our understanding of democratic governance. Existing research has primarily drawn attention to how exchange of resources shapes these relationships largely neglecting the role of contextual conditions. Our contribution is to examine whether parties’ structured interactions with different categories of interest groups vary systematically with the pattern of party competition at the level of policy dimensions. First, we argue that higher party fragmentation in a policy space makes organisational ties to interest groups more likely, due to fears of voter loss and splinter groups. Second, we expect higher polarisation between parties on a policy dimension to make ties to relevant groups less likely due to increased electoral costs. We find support for both expectations when analysing new data on 116 party units in 13 mature democracies along nine different policy dimensions. Our findings underline the value of considering the strategic context in which parties and interest groups interact to understand their relationship. The study sheds new light on parties and interest groups as intermediaries in democracy and contributes to a new research agenda connecting interest group research with studies of parties’ policy positions and responsiveness.

Prominent theories claim that young Europeans are increasingly socialist as well as divided from their elders on non‐economic issues. This paper asks whether age‐based polarisation is really growing in Europe, using new estimates of the ideological positions of different age groups in 27 European countries across four issue domains from 1981 to 2018. The young in Europe turn out to be relatively libertarian: more socially liberal than the old in most countries but also more opposed to taxation and government spending. These age divides are not growing either: today's differences over social issues and immigration are similar in size to the 1980s, and if anything are starting to fall. Analysis of birth cohorts points to persistent cohort effects and period effects as the explanation for these patterns; there is little evidence that European cohorts become uniformly more right‐wing or left‐wing with age. Hence age‐based polarisation need not be a permanent or natural feature of European politics but is dependent on the changing social, political and economic climate.

Several scholars in the United States have recently addressed an increased partisan animosity between Democrats and Republicans, and have termed this phenomenon ‘affective polarisation’. This surge in partisan affective polarisation is perceived to be highly problematic, as it has been found to have a negative impact on the functioning of the party system and even society at large. The aim of this article is to study the concept of affective polarisation in European party systems. It introduces the Affective Polarisation Index (API) that allows for measuring and comparing levels of affective polarisation also in multiparty systems. This novel measure is applied to 22 European democracies and the United States between 2005 and 2016. The results indicate that affective polarisation is acutely present in European party systems, as partisans are often extremely hostile towards competing parties. The most affectively polarised countries are in Central Eastern and Southern Europe where the degree of affective polarisation is notably higher than it is in the United States, while Northwestern European countries are more moderate in terms of partisan feelings. Further analysis reveals that affective polarisation is significantly correlated with ideological polarisation, but the relationship between the two appears to be conditional: in some Western European political systems ideological polarisation does not lead itself to strong interparty hostility, while in Central Eastern Europe a high degree of affective polarisation can be present even in ideologically centrist party structures. These findings validate the claim that ideological and affective polarisation are two distinct aspects of polarisation, and that the latter also merits additional attention.

Political choice is central to citizens’ participation in elections. Nonetheless, little is known about the individual‐level mechanisms that link political choice and turnout. It is argued in this article that turnout decisions are shaped not only by the differences between the parties (party polarisation), but also by the closeness of parties to citizens’ own ideological position (congruence), and that congruence matters more in polarised systems where more is at stake. Analysing cross‐national survey data from 80 elections, it is found that both polarisation and congruence have a mobilising effect, but that polarisation moderates the effect of congruence on turnout. To further explore the causal effect of political choice, the arrival of a new radical right‐wing party in Germany, the Alternative for Germany (AfD), is leveraged and the findings show that the presence of the AfD had a mobilising effect, especially for citizens with congruent views.

Some scholars and policy makers argue in favour of increasing democratic contestation for leadership and policy at the European level, for instance by having European‐wide parties campaign for competing candidates for President of the European Commission ahead of European Parliament elections. But do such changes put the survival of the European Union at risk? According to the consociational interpretation of the EU, the near absence of competitive and majoritarian elements has been a necessary condition for the stability of the EU political system given its highly diverse population. This article contributes to the debate in two ways. First, it develops a more precise understanding of ‘problematic’ diversity by examining how three variables – the heterogeneity, polarisation and crosscuttingness of citizen preferences over public polices – affect the risk of democratic contestation generating persistent and systematically dissatisfied minorities. Second, it uses opinion surveys to determine whether the degree of diversity of the European population is problematically high compared to that of established democratic states. It is found that the population of the EU is slightly more heterogeneous and polarised than the population of the average Member State, although policy preferences in several Member States are more heterogeneous and polarised than the EU as a whole. Strikingly, however, policy preference cleavages are more crosscutting in the EU than in nearly all Member States, reducing the risk of persistent minorities. Moreover, policy preferences tend to be less heterogeneous and polarised, and nearly as crosscutting, in the EU as a whole as in the United States. For observers worried about how high polarisation and low crosscuttingness in policy preferences may combine to threaten democratic stability, these findings should be reassuring.

Using evidence from Great Britain, the United States, Belgium and Spain, it is demonstrated in this article that in integrated and divided nations alike, citizens are more strongly attached to political parties than to the social groups that the parties represent. In all four nations, partisans discriminate against their opponents to a degree that exceeds discrimination against members of religious, linguistic, ethnic or regional out‐groups. This pattern holds even when social cleavages are intense and the basis for prolonged political conflict. Partisan animus is conditioned by ideological proximity; partisans are more distrusting of parties furthest from them in the ideological space. The effects of partisanship on trust are eroded when partisan and social ties collide. In closing, the article considers the reasons that give rise to the strength of ‘partyism’ in modern democracies.

The article discusses some of the paradoxes of minority accommodation in Eastern Europe 30 years after the fall of the Berlin Wall. In the course of doing so, it focuses on four specific issues: volatility, sequencing, a shift from nationalism (group) to social conservatism (grid), and on the radicalisation of mainstream parties. Volatility is tied to the ebb and flow of shifts in the status quo associated with minority accommodation, which elucidates both why radical right mobilisation accelerates and why it loses steam. The expansion of minority rights leads to political ‘extreme reactions’. Sequencing matters since minority accommodation coincided with democratisation in Eastern Europe, so the struggle over minority rights is confounded with a concurrent regime change. Shifts from group to grid refer to the recent rise in socially conservative issues as sources of polarisation. Finally, extremist parties can threaten democratic pluralism. Nevertheless, large radicalised mainstream parties that control parliaments, not small extremist parties, subvert the institutions of democratic oversight. The threat originates from the mainstream and is exacerbated by the fact that liberal democracy has not ‘locked in’ in most of Eastern Europe.

Party ideology plays an important role in determining which government coalitions form. Research on coalition formation tends to focus on the ideological distance between coalition parties. However, the distribution of preferences within the coalition, and the legislature, also has implications for which government coalition forms – that is, a party's willingness to join a coalition depends not only on its prospective coalition partners, but also on the alternative coalitions it could form. Several hypotheses about the effects of legislative polarisation are offered and tested using data on coalition formation in 17 parliamentary democracies in the postwar period. This article also demonstrates how the traditional measure of ideological divisions within coalitions fails to capture certain aspects of ideological heterogeneity within the cabinet (and the opposition) and how Esteban and Ray's polarisation index helps in addressing these deficiencies.

This study explores the polarised nature of climate change politics in the USA. First, it describes the opposing stances on climate change taken by Republican and Democratic leaders. It then uses survey data to show that Republican and Democratic citizens hold widely differing views on climate change and that these differences are greatest among the most educated. Partisan polarisation poses a challenge to those seeking to build support for new policy efforts on climate change.

How does voter polarisation affect party responsiveness? Previous research has shown that political parties emphasise political issues that are important to their voters. However, it is posited in this article that political parties are not equally responsive to citizen demands across all issue areas. The hypothesis is that party responsiveness varies considerably with the preference configuration of the electorate. More specifically, it is argued that party responsiveness increases with the polarisation of issues among voters. To test these theoretical expectations, party responsiveness is analysed across nine West European countries from 1982 until 2013. Data on voter attention and voter preferences with regard to specific policy issues from a variety of national election studies is combined with Comparative Manifestos Project data on parties' emphasis of these issues in their election manifestos. The findings have major implications for understanding party competition and political representation in Europe.

This study explores whether ideological polarization increases political engagement and trust, both of which are central elements of civic culture. Polarization can clarify political positions and thereby simplify the formation of opinions, increase the stakes of elections, and offer more options to citizens. To estimate the impact of polarization from a causal perspective, we exploit variation within individuals over time using individual-level data from the Swiss Household Panel spanning from 1999 – 2023, amounting to 178,251 observations from 28,187 persons. Ideological polarization at the individual level is measured by a process of increasing extremity of the self-position on the left-right scale. In addition, we test how polarization of cohabiting household members has spillover effects on political engagement and trust. For political engagement, we adopt a comprehensive approach, focusing on interest in politics, participation in popular votes, party identification, and frequency of political discussions as dependent variables. Political trust is measured as confidence in the federal council. To analyze the data, we primarily use fixed effects models, complemented by a pooled Ordinary Least Squares (OLS) model, and cross-lagged models to address reverse causality. Results show that ideological polarization does promote engagement but has a weak negative impact on political trust. This effect remains significant when controlling for affective polarization. Additionally, there is an overall increase in political engagement and a decrease in political trust if partners living in the same household become more extreme in their ideological preferences.

Affective polarization is often blamed on the rise of partisan news. However, self-reported measures of news consumption suffer serious flaws. We often have limited ability to characterize partisan media audiences outside of the United States. I use a behavioural data set of 728 respondents whose online behaviour was tracked over four weeks during the 2019 Canadian federal election. These data were paired to a survey for a subset of respondents. I find that audiences for partisan media are small, and web traffic is driven by an even smaller share of the population. There are few major partisan differences in news media use, and partisan news exposure is higher among highly attentive, sophisticated news consumers, rather than those with strong political commitments.

This paper examines why, some 25 years beyond the Belfast-Good Friday Agreement, Northern Ireland (NI) remains a highly polarised society despite the return of devolution (in February 2024) after a 2-year hiatus. Using the theoretical lens of social capital, it draws on the Northern Ireland Life and Times survey and the World Values survey (the latter conducted for the first time in NI) to examine levels of trust as a pre-requisite to reconciliation between the two main communities. The research finds a high degree of trust towards people of another religion and limited affective polarisation across the main political parties. Yet government community relations policies appear to have had limited impact over time and may contribute to ‘bad social capital’ through bonding within communities at the expense of ‘the other’. The paper considers tackling social and economic inequalities, common to both communities, as a means of bridging social capital.

Neutral and singly ionised states of the magnesium (Mg) are the origin of several spectral lines that are useful for solar diagnostic purposes. An important element in modelling such solar lines is collisional data of the Mg with different perturbers abundant in the Sun, specially with neutral hydrogen. This work aims at providing complete depolarisation and polarisation and population transfer data for Mg II due to collisions with hydrogen atoms. For this purpose, a general formalism is employed to calculate the needed rates of MgII due to collisions with hydrogen atoms. The resulting collisional rates are then employed to investigate the impact of collisions on the polarisation of 25 Mg II lines relevant to solar applications by solving the governing statistical equilibrium equations within multi-level and multi-term atomic models. We find that the polarisation of some Mg II lines starts to be sensitive to collisions for hydrogen density $n_H \!\gtrsim\!$ 10$^{14}$ cm$^{-3}$.

We conducted a study on the X-ray polarisation properties of MCG-5-23-16 by analysing long-term monitoring data from NuSTAR jointly with IXPE observations made in May and November 2022. The re-analysis of IXPE data gives model-dependent polarisation degree, PD (%) = $1.08\pm0.66$ in the energy band 2–8 keV, which agrees with previous studies within error bars. The model-independent analysis of PD poses an upper limit of $\leq3.8$ ($1\sigma$ level) for the same energy band. The observed upper limit of PD, along with broadband spectral analysis (2–79 keV) using an accretion-ejection based model, allowed us to derive the corona geometry (i.e. radius and height) and the accretion disc inclination ($\sim33^\circ$). Additional NuSTAR observations were also analysed to gain insights into the accretion flow properties of the source and to estimate the expected polarisation during those epochs with PD $\sim 4.3\%$. The radius and height of the corona varies between $28.2\pm3.1 - 39.8\pm4.6$ r$_s$ and $14.3\pm1.7-21.4\pm1.9$ r$_s$ respectively, with a mass outflow rate from the corona measuring $0.14\pm0.03-0.2\pm0.03$ Eddington rate ($\dot m_{\mathrm{Edd}}$). The estimated PD values were nearly constant up to a certain radial distance and height of the corona and then decreased for increasing corona geometry. The spectral analysis further provided an estimate for the mass of the central black hole $\sim2\times 10^7$ M$_\odot$ and the velocity of the outflowing gas $\sim0.16-0.19c$. A comparative broadband spectral study using reflection-based models estimates the disc inclination between $\sim 31^\circ\pm8^\circ-45^\circ\pm7^\circ$, and yields an expected PD of 3.4–6.0%. We also found a weak reflection fraction and a less ionised distant reflecting medium. The expected PD measured using accretion-ejection and reflection models is less compared to the expected PD measured for a given disc inclination of $45^\circ$. Our modelling of the disc-corona-outflows and polarisation connection can be extended and validated with data from the recently launched XPoSat, India’s first X-ray Polarimeter Satellite, offering potential applications to other sources.