Introduction

Populist parties have become increasingly successful in Europe and not only in terms of their increasing vote share. Despite some prominent exceptions, they have now largely emerged from the shadows of permanent opposition and pariah party status. Populist parties have a chance to take on governing roles. They play an active part in the politics of the European Union. Yet doubts remain about whether and in what ways populist parties challenge liberal democracy. This is despite the fact that populist parties in Europe typically find success in free and fair elections, and despite variation among them in terms of ideology and accommodation with the institutional status quo. As Mudde and Rovira Kaltwasser (2012) have argued, populist parties can function as a ‘correction’ to liberal democracy by highlighting popular grievances and lack of elite responsiveness. However, they may also constitute a challenge to liberal institutions guaranteeing the rule of law, judicial independence, and certain individual rights, and to core democratic practices such as media pluralism, fair procedures, and constitutional neutrality.

In this special issue of Comparative European Politics, we enter debate on this complex issue by examining two main questions: How do those who disagree with populist parties oppose them? And how ought the opponents of populist parties engage if they are to remain consistent with liberal democratic norms? By addressing these questions, we take the first step in tackling the pressing theoretical and practical problems of how best to respond to populist parties. The articles in this issue present findings from the first stage of an interdisciplinary research project on ‘Populism and Democratic Defence in Europe’ funded by the Carlsberg Foundation (CF20-008) and executed by scholars at Roskilde, Aarhus, Wroclaw and Lund universities. They have been joined by a leading expert on populism from the Australian Catholic University.

In this introduction, we begin by addressing the question of why we focus on opposition to populist rather than other kinds of political parties, arguing that the success of populist parties and their ambiguous orientation to liberal democracy create new kinds of democratic and strategic dilemmas. We then turn to outline how we conceptualize opposition to populist parties in contemporary Europe and how our approach fills several gaps in the existing literature on populism and the overlap** fields of militant democracy and democratic defence. Discussion then turns to the centrality of tolerance and intolerance for understanding and evaluating that opposition. As we explain, (in)tolerance provides a fundamental point of encounter between the political science and political theory perspectives we bring together in the special issue. In the last part of this introduction, we summarize the individual empirical and conceptual contributions of this special issue.

Why study opposition to populist parties? Ambiguity and democratic dilemmas

There is both scholarly and public disagreement about how best to conceptualize populism. However, most definitions of populism point to a vision of society sharply divided between two groups, ‘the people’ and the ‘elite’, as a core characteristic of populist appeals (Canovan 1999; Mudde 2004; Laclau 2005; Müller 2016a; Mudde and Rovira Kaltwasser 2017; Weyland 2017; Ostiguy 2017). The ‘people’ are typically conceived in moralistic terms as ‘pure’ and the elite as ‘corrupt’, as Mudde (2004) put it in his seminal piece. Politics is pitched as a struggle between these two groups, often conceived in Manichean terms as an antagonistic battle where there are only friends and enemies. Yet as Brubaker observed, ‘speaking in the name of the people…is a chronic and ubiquitous practice in modern democratic settings’ (2017: 357–385; see also: Canovan 1999, 2002). As such, several scholars have argued that it is better to see populism as characteristically prioritizing appeals to the people against the elite more often than other parties, or to speak of populism as a matter of degree (Hawkins 2010; Rooduijn and Pauwels 2011; Weyland 2017; Rooduijn 2019).

Our interest in studying opposition to populist parties is rooted in the recognition that despite populist appeals to popular sovereignty and ‘real democracy’, the relationship between populism and democracy is in fact highly ambiguous. Political theorists take contrasting positions on this issue. Some theorists see (the logic of) populism as an important vehicle for mobilizing demands and grievances from alienated and marginalized groups in society (Laclau 2005; Mouffe 2018; Hansen 2017; Canovan 1999). In principle, populist movements and parties can bring together a diversity of groups in a populist political alliance and place pressure on the political establishment and unresponsive political institutions and eventually take over government. On gaining power, they can potentially increase the openness and responsiveness of institutions to popular demands and circumscribe the power of counter majoritarian institutions, such as independent central banks, (other) regulatory agencies and constitutional courts, which serve the vested interests of the establishment whether local or global. In a similar vein, populism has been interpreted as a legitimate struggle for recognition among groups who have not only lost in terms of material benefits and security, but also in terms of social status.

For other theorists, some expressions of populism constitute a challenge to the institutions and the rights that secure conditions of democratic symmetry; that is, the institutions and rights which enable the exercise of popular sovereignty in the first place (Müller 2016a, b; Urbinati 2019; Rostbøll 2023; Arato & Cohen 2021). In this light, enfeebling the rule of law and the security of rights guaranteed inter-alia by independent courts, gerrymandering, shortcutting of parliamentary procedures and skewing rules and funding provisions for media and civil society organizations are real challenges to the proper functioning of democracy. They are problematic despite their alleged purpose of making institutions more responsive to the demands of ‘the people’. Thus to protect democracy, they require some response.

Our approach does not presuppose that populist parties necessarily threaten liberal democracy, although in some cases we do think that they do. However, the notion that populists are problematic in relation to democracy is fairly widespread. The frequency with which opponents of all kinds of populist parties claim to act in defence of democracy is an important indication that this is what many believe is ultimately at stake. It is easy to find examples where opponents ranging from heads of state to participants in local demonstrations, frame the acts they oppose as problematic in democratic terms. Opponents often describe populist parties as authoritarians—as Nazi’s, fascists, Stalinists, for example––or use some other equally unflattering designations—such as ‘racist’, ‘anti-Semitic’, ‘Islamophobic’, ‘xenophobic’ ‘corrupt’ or ‘illiberal’—to describe them. Populist acts have been framed as a ‘mockery of democracy’, ‘throwing away basic values’, ‘paving the way for extremists’, ‘inciting racial intolerance and hatred’, among many other things. National and international courts have ruled that the actions of populist parties violated liberal democratic norms, the rule of law, or civil and human rights. National and transnational NGOs and media organizations have investigated and disseminated critiques of populist parties on similar grounds. In Poland, one movement even explicitly organized under the banner of the Committee for Defence of Democracy (KOD) soon after Law and Justice (PiS) won power in 2015.

At the same time, we do not claim that every act of opposition against populist parties is an act of democratic defence. Some of those opposing populist parties may care little about liberal democracy, or primarily object to populist parties where policies damage their material well-being. Anti-populist frames can be deployed to discredit what might be legitimate programmes to transform the existing status quo (Stavrakakis 2014, 2018; Miró 2019). More generally, opponents may not appreciate the finer points of theoretical arguments about the relationship between populism and democracy, perhaps over-estimating the potential damage to liberal democratic institutions in some cases, while under-estimating it in others. Rather, it is best to conceive of democratic defence as one of several fields in the broader political terrain upon which opposition to populist parties takes place.

It is the combination of populist successes and the very ambiguity of the relationship between populism and democracy that makes the study of opposition to populist parties worthy of study. It creates new kinds of democratic and strategic dilemmas, which are likely to affect the kinds of responses deployed by other political actors against populist parties. Opponents claiming to defend democracy are confronted with the argument that populists themselves are the true democrats. Opponents will have to take into account the possibility that their actions will have perverse effects, perhaps increasing support for populists and fueling political polarization. Despite disagreement, some may choose accommodation with populist parties, especially where they are seen as legitimate by many voters. These dilemmas raise profound questions about the conditions under which populists deserve political tolerance. The articles in this special issue explore the implications of this new conjuncture, examining how those opposing populist parties design strategies negotiating these dilemmas and how well they align with the principles of liberal democratic politics.

What is opposition to populist parties?

All articles in the special issue examine from one perspective or another opposition to populist parties, defined as initiatives that seek to marginalize populist parties in the public sphere or limit their ability to implement illiberal or anti-democratic policies (Bourne 2022). As existing empirical studies and several articles in the special issue show, opposition can take a wide variety of forms, involving many different types of political actors.

Populist parties in Europe are not as a rule, subject to party bans, but sometimes face other rights-restrictions such as surveillance of the right-wing Alternative for Germany by the Office for the Protection of the Constitution. Alternative for Germany, along with National Rally in France and Flemish Interest in Belgium has been subject to electoral, governmental, parliamentary and a more generalized public ostracism. In other cases, such as that of the Danish People’s Party and more recently the Sweden Democrats, centre-right competitors have been willing to accept parliamentary support to sustain government. A long list of right- and left-wing populist parties joined or led coalition governments at the national or regional level, including Freedom Party in Austria, Five Star Movement and League in Italy, Podemos and Vox in Spain, Progress Party in Norway, the Action of Dissatisfied Citizens in Chechia, Direction—Social Democracy in Slovakia, SYRIZA in Greece, the Slovenian Democratic Party, the Hungarian Civic Alliance (Fidesz) and Law and Justice in Poland.

It is not just other political parties that oppose populist parties. These organizations and their leaders often find themselves in court. Parties such as the Flemish Block, and party leaders such as the National Front's Jean Marie Le Pen, Party of Freedom's Geert Wilders or The Finns Party's Jussi Halla-aho were convicted for racism, hate crimes, or holocaust denial. Populist party leaders, such as Forward Italy’s Silvio Berlusconi, the Northern League’s Umberto Bossi, the Slovenian Democratic Party’s Janez Janša, and the Austrian Freedom Party leader Heinz-Christian Strache were convicted for various corrupt practices, including bribery, tax fraud, embezzling public funds, and offering favours to party funders. The Northern League was convicted for fraudulently claiming elections expenses, while Alternative for Germany was fined for illegal campaign contributions.

Populist parties in government may see their signature policies toppled in adverse court rulings, use of presidential vetoes, or from losing support from parliamentary allies. In 2013, Janez Janša’s Slovenian Democratic Party lost power when coalition partners supported a constructive motion of censure in favour of a new governing coalition. In 2017, the Czech Action for Dissatisfied Citizens’ coalition partner and opposition parties joined forces to enact the so-called Lex Babis, introducing new rules limiting media ownership for cabinet ministers as well as their ability to own companies receiving state funding. In Italy, the formal constitutional powers of the President of the Republic, which include appointment of ministers, a legislative veto, and the dissolution of parliament, have constrained the activities of successive populist led governments. In the midst of mass protests in 2017, Polish President Andrzej Duda used veto powers to (at least temporarily) delay two laws central to Law and Justice judicial reforms weakening the autonomy of the Polish courts. Where they remain autonomous, constitutional courts have struck down problematic laws, including rulings by the Italian Constitutional Court which blocked various legislative initiatives promoted by Forward Italy and the Northern League (now League). Civil society actors actively oppose all kinds of populist parties, whether they are journalists investigating allegations of wrongdoing, moral authorities like church leaders, public intellectuals and transnational human rights NGOs criticizing populist parties, or social movements undertaking spectacular or disruptive protests. Whether through conviction or pressured by others, for example, Alternative for Germany and the Sweden Democrats have faced obstacles by private venue owners to let them use their facilities. In Italy, ‘the Sardines’ movement crowded into city squares across Italy demonstrating sizeable support for an explicitly anti-populist mobilization targeting the League. In Poland, mass protests and a women’s strike against Law and Justice temporarily led the Law and Justice to abandon reforms to tighten abortion laws. In Bulgaria, Boyko Borissov’s Citizens for European Development of Bulgaria faced mass protests over corruption scandals, leading to a dramatic loss of votes in subsequent elections. In Slovakia, protests following suspicious circumstances surrounding the murder of journalist Ján Kuciak, who was investigating allegations of fraud and corruption linked to the ruling Social Democracy-Direction (SMER-SD), led to the resignation of long-standing SMER-SD leader and prime minister Robert Fico, among others.

In the international sphere, the Court of Justice of the European Union has ruled on several occasions that judicial reforms pursued by the Polish Law and Justice (PiS) party violated EU treaty obligations requiring judicial independence within EU member states. Among other things, Viktor Orbán’s Hungarian Civil Alliance (Fidesz) has been the subject of rulings on illiberal reforms affecting judges, NGOs, and foreign universities. The European Court of Human rights has ruled that PiS- or Fidesz- led government actions have violated freedom of assembly, expression, thought, conscience or religion, rights to a fair hearing and access to a tribunal, among other things. Both have been called into Article 7 Treaty on the European Union talks about risks such policy reforms pose to the EU’s liberal democratic values. The European Commission initiated official procedures to sanction Fidesz under the EU’s rule of law budget conditionality mechanism.

In addition to IoPPs geared towards change in the short-to-medium-term, IoPPs may also pursue longer-term change, IoPPs may take the form of policy and legislative responses to address underlying grievances of populist party supporters. These include minimum income policies or increased public spending on housing or health to address perceived social inequality, or reform of immigration and integration policies to address cultural insecurity, or anti-corruption campaigns and institutional reforms to address problems of political trust. They can include longer-term programmes of civic education or international programmes for democratic education.

In sum, opposition to populist parties is varied, involving a wide-range of political actors, operating at multiple territorial levels, across several times scales and involving many different kinds of legal, political and cultural initiatives. Yet as we now go on to suggest, the existing theoretical literature does not adequately acknowledge this complexity.

A neglected field in the study of populism

In line with the growing importance of populist parties, scholarly work on populism has mushroomed. This literature largely focuses on the questions of how to define populism, its causes, and consequences for liberal democratic politics (e.g. Laclau 2005; Mudde 2004; Mudde and Rovira Kaltwasser 2013; van Kessel 2015; Müller 2016a, b; Moffitt 2016; Gerbaudo 2018; Norris and Inglehart 2019; Fieschi 2019; Mouffe 2018; Pappas 2019; Urbinati 2019, among many others). While we now have many case studies to hand, and good knowledge about causes, we know a great deal less about opposition to populism and the consequences of this opposition. What we do know comes from traditions that provide an incomplete picture. The strongest contributions so far come from the law and philosophy-dominated tradition of ‘militant democracy’ (e.g. Loewenstein 1937; Rummens and Abts 2010; Müller 2014; Kirshner 2014; Müller 2012 and 2016b; Malkopoulou and Kirshner 2019); the political science-dominated ‘democratic defence’ approach (e.g. Capoccia 2005; Downs 2012; Van Spanje 2018; Akkerman, de Lange and Rooduijn 2016; Albertazzi and Vampa 2021); and law and political science scholarship on the EU’s rule of law crisis (e.g. Sedelmeier, 2017; Schimmelfennig and Sedelmeier 2020; Kelemans 2020; Scheppele et al 2020; Pech and Kochenov 2021). These literatures provide many insights to draw on but leave important gaps: Research often focuses on extremists rather than populist parties, which  typically have a much more ambiguous orientation to liberal democracy than extremist parties. Many studies focus exclusively on responses to opposition parties within the state, rather than parties big enough to govern. Those looking at EU responses rarely focus on broader consequences for democratic oppositions within states in any depth. Civil society is more-often-than-not out of the picture. Rovira Kaltwasser and Taggart’s (2016) Democratization special issue comes closest to providing an integrated approach but only examines six populist led-governments.

Political theorists addressing responses to populism tend to take a longer-term perspective, often focusing on how to address root causes of support for populist parties. Several point to the possibility of making democratic institutions more open and responsive and to make sure that democratic respect is exhibited to all citizens (Arato 2019; Arato and Cohen 2021; Michelsen 2022; Rostbøll 2023). Others propose policies addressing the social and cultural deficits which typically mobilize populist supporters, such as low levels of material welfare and social and cultural recognition (Azmanova 2019). Some theorists argue in favour social movements as a site of opposition, which, in conjunction with political parties, can create new forms of solidarity and channel citizens’ demands otherwise taken up by populist parties into the political system (Arato and Cohen 2021). Similarly, others propose that parties opposing populists should provide a framework not only for choice between real alternatives but also for a responsive interaction between party supporters, members and the party leadership (Bértoa and Rama 2021; Urbinati 2019). Despite many important insights, political theorists tend to ignore the theoretical implications of actual practices of opposition to populist parties, especially short-to-medium-term initiatives undertaken by varying types of political actors. While the role of political theory is also to provide alternatives to current practices, actively addressing what political actors actually are doing increases its relevance. More specifically, it will improve the ability of political theory to reflect on the appropriateness of different kinds of response and to articulate the role of different types of actors as carriers of democratic defence, consolidation and/or progressive change.

In short, existing research does not provide sufficient theoretical and conceptual tools to understand opposition to contemporary European populist parties, who are often big, powerful and operate on a daily basis within the EU’s system of multilevel governance. We need more knowledge about how different types of actors can and do respond either alone or in combination with others and with what means.

As we spell out in more detail below, the articles in this special issue address shortcomings in the existing literature in several ways. Firstly, the articles specifically address opposition to populist parties in government and in opposition initiated by a wide range of political actors—public authorities, political parties and civil society actors—operating across multiple territorial levels of government. Bourne’s typology is specifically designed to incorporate this wide range of political actors across territorial levels. Laumond's article accounts for strategies adopted by public authorities, political parties and civil society actors against Alternative for Germany. Ensuring that the important role of political parties as opponents to populist parties is addressed, Holst Nicholaisen examines party strategies against the Danish People’s Party. Campo focuses attention on civil society actors in Italy, aiming to account for varying responses to the Five Star Movement and the League. Moroska-Bonkiewicz and Domagała examine mobilization by international actors, particularly the European Union, and their interaction with Polish and transnational civil society actors. Tuovinen focuses attention on collaboration between public authorities, political parties and civil society actors as allies dealing with the ‘detection problem’, where populist appeals to popular sovereignty made it difficult to identify challenges to liberal democratic institutions and values. Malkopoulou and Moffitt address appropriate response strategies for public authorities in the light of the differences between populist and extremist or anti-democratic parties. Olsen focuses attention on the circumstances in which political parties and civil society actors ought to adopt tolerant or intolerant modes of engagement with populist parties. Our actor-centred approach is one way in which we aim to integrate political science and political theory perspectives on opposition to populist parties. A second is engagement with philosophical concepts of tolerance.

What are tolerant and intolerant responses to populist parties?

Toleration is the central concept in our analyses. We distinguish between tolerant and intolerant ways of responding to populist parties. We map and discuss the legitimacy of different tolerant and intolerant responses. We have chosen to frame our studies in this way because it enables us to build a productive bridge between empirical political science and political theory.

In political theory, toleration means that you do not prohibit that which you find wrong even though you (think you have or will) have the power to do so. To be tolerant means that there is something you object to, but also that you have other reasons for not rejecting or prohibiting it. Reasons for toleration can be prudential in relation to goals such as maintaining peace and public order. They can be epistemic, pertaining to uncertainty about the cogency of the position of your opponent as well as your own. Moreover, they can be principled, based on respect for your opponent, as a moral and political equal (Galeotti 2015). By contrast, intolerance means that you do prohibit that and those you find wrong. Historically, the violation of prohibitions had dire consequences, for example for religious heretics. Religious persecution and wars were prime examples of intolerance. Today, intolerance generally means something less violent and lethal. Intolerance is not about eliminating opponents physically. Fundamental rights place important boundaries on our actions. However, intolerance does entail reducing as much as possible the influence of your opponents’ beliefs and practices. Oftentimes, this implies seeking restrictions in their civil and political rights and/or their ability to exercise them fully.

In political science, the study of political tolerance focuses on the propensity to support or deny the full set of political and civil rights to those whom are considered our worst opponents or the most controversial groups in society (e.g. Sniderman et al. 2014, 2020). Tolerant responses are from those who insist that everyone is entitled to the same rights as everyone else. Intolerant responses call for exceptional treatment by denying opponents some of their rights. As spelt out more fully below, this understanding of tolerance and intolerance is mirrored in Bourne’s typology issues and empirical case studies by on German responses to the AfD by Laumond, on party responses to Danish People’s Party by Holst Nicholaisen, by Campo’s work on civil society responses to the Five Star Movement and League in Italy and Moroska-Bonkiewicz’s and Domagała’s article on EU and Polish civil society responses to the Law and Justice Party. More specifically, these articles apply an understanding of tolerant modes of engagement with populist as based on ‘normal politics’ where opponents apply the same norms, rules and practices in democratic politics and international relations as those applied to other parties and states not led by populists. In contrast, intolerant modes of engagement with populist parties are characterized by ‘exceptional politics’ where the rights of populists are restricted or their exercise obstructed by exclusion or more or less coercive interventions by opponents.

Framing the empirical analysis in terms of tolerant and intolerant modes of engagement with populist parties rather than solely in terms of normal and exceptional politics makes it possible to relate to an age-old political theoretical discussion concerning how to handle strong disagreements (Forst 2013). In a theoretical landscape defined by political liberalism and the notion of the neutral state, (in)tolerance is typically discussed in relation to religious and cultural issues rather than politics as such (Williams and Waldron 2008; McKinnon 2007). Obviously, this does not mean that tolerance and intolerance are irrelevant for politics. Politics is very often—if not always—characterized by disagreement and tolerance and intolerance concern how you respond to this disagreement. We study how different types of actors respond to the disagreements that they have with populist parties of various kinds. This includes not only public authorities, who possess the actual power to tolerate or not in the sense of being able to restrict the rights of populist parties. It also includes political parties and civil society organizations. With these actors, the practice of toleration and its opposite take on other forms. Intolerant parties may employ their resources to exclude populist parties from the central arena of the political game by permanently ostracizing or excluding populist parties from government. Tolerant parties, while still disagreeing with their opponents, may follow regular forms of interaction with populist parties, involving dialogue, cooperation and compromise, as well as fierce competition. Intolerant civil society actors use their power to exclude populist parties, including applying different forms of coercion against them and their supporters. Tolerant civil society actors explore other strategies which respect to the rights of populist parties and their supporters, but which nonetheless aim to reduce their support and influence to the extent that they do not endanger important principles and interests. Tolerance does not mean that disagreement disappears. The ambition is still to keep the views that you disagree with from determining public policy and the structure of public institutions.

Normatively, we consider what are justifiable responses to populists given the overall goal of preserving democratic institutions. Here prudential, epistemic and principled reasons all come into play, as populists often are a liminal case in terms of their commitment to basic democratic principles and in terms of their political practice. The starting point is that as political and moral equals, populists should enjoy equal rights and in this sense, they should as a minimum be tolerated. However, to the extent that populist parties in speech and action do not support democratic institutions and respect the democratic rights of others—perhaps in a process of metamorphosing from populists into something more authoritarian (Arato and Cohen 2021)—less tolerant responses would be justified, taking into account, however, both the epistemic uncertainty about their actual commitments and prudential reflections on the possible negative effect of reacting towards populists with intolerance.

As spelt out below, these are issues of central importance in articles by Tuovinen on how institutional frameworks can detect ideologically problematic and potentially intolerable parties with the assistance of civil society actors; by Malkopoulou and Moffitt on what the appropriate responses from the side of public authorities are, given that populist parties strong commitment to the democratic ideal of self-government by the people; and by Olsen on what kinds of tolerant and intolerant responses by civil society actors and political parties may be justified in order to secure (liberal) democracy, its political culture, the rights of citizens and core institutions. We now turn to summarize the main contributions to the special issue.

Initiatives opposing populist parties: typology and cases studies

Departing from the critique of existing classification schemes in work on ‘militant’ and ‘defending’ democracy, Bourne’s article on Initiatives Opposing Populist Parties in Europe: Types, Methods, and Patterns presents a new typology for classifying initiatives opposing populist parties (IoPPs). Acknowledging the range of responses to contemporary populist parties sketched above, the first dimension of the typology incorporates responses to public authorities, political parties, and civil society actors, regardless of whether they operate at the state and supranational levels. The second dimension distinguishes between intolerant and tolerant modes of engagement with populist parties, develo** a practice-based distinction where intolerant IoPPs suspend, and tolerant IoPPs observe rules, privilege and respect typically given to political parties at home due to their role in democratic politics, and abroad due to their governing status. Six types of IoPPs emerge: the intolerant IoPPs of rights-restrictions by public authorities, ostracism by political parties and coercive confrontation by civil society actors; and the tolerant IoPPs of ordinary legal controls and pedagogy by public authorities, forbearance by political parties and adversarialism by civil society actors. The typology was initially built on theoretical constructs from the existing literature but refined and extended in the light of empirical research by country specialists, most of whom contribute to this special issue. As Bourne’s article spells out in more detail, country specialists collected data from newspapers on initiatives opposing selected populist parties using a method inspired by protest event and political claims analysis (Hutter, 2014). By observing variation in the types of IoPPs used against populist parties in Germany, Denmark, Italy, and Poland—countries selected for variation in populist parties’ governing status, ideological differences, and varying degrees of populist discourse—the article then goes on to sketch four models of opposition to populist parties. These form the starting point for subsequent case studies, which then seek to account for distinctive features of each model.

The German model of opposition to populist parties is discussed in Laumond’s article, Increasing toleration for the intolerant? ‘Adapted militancy’ and German responses to Alternative für Deutschland. Compared to other models discussed in the special issue, data on IoPPs targeting Alternative für Deutschland showed a high concentration of intolerant IoPPs. This included rights-restrictions by public authorities, such as surveillance by the Federal Office for the Protection of the Constitution, ostracism by political parties, and coercive confrontation by civil society actors. Yet, in line with patterns in the other cases, we observed more than twice as many tolerant IoPPs. Tolerant IoPPs included ordinary legal controls, such as those addressing illicit party funding; policy co-optation; as well as many cases of non-coercive, adversarial forms of opposition by civil society actors. Exploring explanations for this pattern of opposition, as well as the increasing use of intolerant IoPPs over time, Laumond’s article sheds light on how the emergence of the AfD affected long-standing practices of militant democracy in Germany. It points to four factors explaining the German model of adapted militancy and change over time: the radicalisation of the AfD; legacies of the militant democracy tradition; the distribution of power among AfD opponents; and learning dynamics affecting political actors, public authorities, and civil society groups differently.

The Danish ‘political competition’ model of opposition to populist parties is discussed in Holst Nicholaisen’s article, From Toleration to Recognition: Explaining Change and Stability in Party Responses to the Danish People’s Party. In striking contrast to the German case, our data showed that opposition to the Danish People’s Party almost exclusively took the form of tolerant IoPPs, and more than any other case examined here, showed a high concentration of forbearance IoPPs by political parties. In other words, opposition principally took the form of cooperation, but also the extensive co-opting DF’s signature policies on immigration. In his article, Holst Nicholaisen examines why the main governing parties—the Liberals (Venstre) and Social Democrats—intensified cooptation and cooperation strategies towards the Danish People’s Party and what explained party differences in the timing and execution of such strategies The author argues that multiple factors account for the party strategies: intra-party dynamics, external shocks, party system constraints, and the competitive strategies, leadership, and success of the Danish People’s Party itself. Gradually, the main governing parties chose to recognize and provide representation of the grievances raised by the Danish People’s Party and their voters rather than marginalize it from the public sphere.

The Italian model of opposition to populist parties is discussed in Campo’s article, Differentiated Opposition in Collective Mobilization: Countering Italian Populism. Opposition to the right-wing populist League and the ambiguous, post-ideological Five Star Movement (5SM), both of which have substantial governing experience, has predominantly been tolerant. This includes a comparatively high proportion of ordinary legal controls by pubilc authorities, and non-coercive, adversarial protest opposition by civil society actors. There is, however, a striking contrast between civil society responses to the 5SM, which were predominantly non-coercive adversarial IoPPs, and their responses to League, which faced a higher proportion of both coercive confrontational and non-violent, adversarial IoPPs by civil society actors. Addressing this difference, Campo’s article asks, why have some civil society actors used intolerant opposition in connection with these populist parties, while others used tolerant forms? Campo addresses this question analysing frames deployed in the claim-making of civil society actors involved in protests against the M5S representatives in Tor Sapienza in 2014, against 5SM leader Beppe Grillo in anti-vaccination protests in 2019, against League by the Mai con Salvini movement between 2015‒2017, and the 2019 Sardine movement, also targeting League. Campo’s analysis shows that actors adopting intolerant initiatives against populist parties frame coercive act as a defensive tool opposing an illegitimate, threatening antagonist, while those adopting tolerant forms of opposition do not do so. Anti-populist framing is more likely to lead to tolerant forms of opposition.

The Polish model of opposition to populist parties is discussed in Moroska-Bonkiewicz and Domagała’s article, Who is Fighting Populists in Power? The ‘Pincer Movement’ Model of National and International Opposition to Democratic Backsliding in Poland. Like the Danish case, opposition to the Law and Justice Party has almost exclusively taken the form of tolerant IoPPs, although in the Polish case there was a higher proportion of initiatives involving ordinary legal controls and pedagogy by public authorities. This included use of checks against executive power, court cases and condemnatory declarations. Polish civil society was also shown to be highly mobilized against the Law and Justice government. However, the most striking contrast with the other cases examined here was the high proportion of IoPPs by international and transnational actors, particularly from the EU, who often worked together with domestic actors in a pincer-movement against Law and Justice. Using the theoretical lens of Europeanization and interview methods, Moroska-Bonkiewicz and Domagała explore externalization strategies of Polish NGOs, which aimed to exert pressure on the Law and Justice government through appeals for support from international actors. The authors point to three factors explaining the shift of Polish NGO’s democratic defence strategies to the European level: the changing multi-level opportunity structure, the construction of national and transnational coalitions for democratic defence; and a common pro-European frame and strong commitment to the democratic values, which helped NGOs to shape the European structure of opportunities.

Conceptual and institutional limits of political and legal (in)tolerance towards populists

The variated responses to populists reflect national contexts and learning processes among their opponents, but also populists’ own strategies and ambiguous commitment to liberal democratic principles. The latter makes it unclear whether populists rightly merit toleration, since it is uncertain that they themselves are tolerant. It thus raises the question how the institutional framework of liberal democracies in Europe can detect and respond to political agendas that might undermine it, what the extent of political toleration towards populism should be, and how tolerance should be exercised.

Tuovinen considers in his article ‘Resisting Ambiguously Anti-Democratic Parties—What role for the state, political parties and civil society?’ how to protect constitutional democracy from ambiguously anti-democratic parties, which, like some populist parties, have an ambiguous commitment to the precepts of constitutional democracy. The key problem is how to identify or ‘detect’ ambiguously anti-democratic parties before they reach a position within the constitutional system that enables them to undermine it. Traditionally, the detection problem has been conceived as a question about how public authorities can detect and respond to problematic parties (Rijpkema 2018; 2019). Tuovinen argues that this conception unduly narrows our view of the detection process and the available responses. Public authorities have to follow legal procedures requiring strict burdens of proof that a party constitutes a danger to constitutional democracy before they can act. By contrast, civil society actors and political parties concerned about the protection of constitutional democracy are less constrained by the rigidity of legal and are, as demonstrated in our empirical studies, able to react faster and in variated ways. Political parties may use their political platform as a way of contesting the often crude and unclear ideas of ambiguously anti-democratic parties and expose them to the electorate. Civil society actors, like the Italian Sardines, may also appeal to a broader audience’s commitment to constitutional democracy both through criticism of the statements and ideological positions of problematic parties and by providing an exemplar of alternative and positive political behaviour. Civil society actors do not have any special constitutional status like public authorities or political parties and enjoy greater flexibility in their responses. Public authorities, political parties and civil society actors can act separately or together. Tuovinen suggests that although they have different constitutional statuses, coordinated efforts predominantly combining tolerant modes of engagement will be most adequate in detecting and reacting to ambiguously anti-democratic parties.

In a similar vein, Malkopoulou and Moffitt in their article ‘How Not to Respond to Populism: Militant Democracy, Toleration and the Democratically Ambiguous Nature of Populism’

argue that despite the minimal consensus that populism poses a number of threats to liberal democracy it is important for public authorities not to employ means against populist parties that were developed in the context of combatting anti-democratic and extremist parties. There are significant differences between populist parties and these other political actors. Malkopoulou and Moffitt posit that neither the ‘intolerant’ militant democratic defence nor the ‘tolerant’ defence offer fully satisfying responses to populist parties because they were originally conceived as responses to different phenomena. For public authorities to address populist parties successfully, their responses should contain its most egregious characteristics while salvaging its productive side. To account for the fact that populism has emerged due to a combination of circumstances, whose prime ingredient is social injustices, public authorities should move beyond the binary of toleration and intolerance. Instead, they must capture the social dynamics that animate populist parties through a range of policies that rehabilitate the social face and social legitimacy of democracy. Democracy’s vulnerability should not be eliminated altogether but be turned into a productive force that takes its cues from existing shortcomings and imperfections and moves democracy into a new and better direction.

The final article by Olsen Citizens’ Responses to Populists in the Borderland between Tolerance and Intolerance moves the perspective from public authorities to political parties and civil society actors and asks what responses from their side towards populists would be justifiable. To answer the question, he outlines the basic features of a theory of political toleration covering both ideal and non-ideal circumstances. Building on case study findings, he argues that what can be considered tolerant responses varies with the circumstances and the nature of the political process, and, further, that there is an intermediary conceptual space, a borderland, between toleration and its opposite, which indicates that tolerance and intolerance are not a matter of a clean dichotomous difference and that there are relevant intermediary forms. To the extent that it becomes clear that populists do not merit toleration because they do not respect their opponents as free and equal citizens or because they are working to undermine the rights and institutions of liberal democracy, it is increasingly appropriate to employ these intermediary forms. Such employment should, however, always take into consideration whether they might be counterproductive, for example because they, as Malkopoulou and Moffitt argue, might ignite a populist fire fuelled by the idea that the elite is persecuting the only true representatives of the people in order to keep its own privileges.

The eight articles of this special issue map the IoPPs adopted against different kinds of populist parties, observe and account for variation among them, and discuss the appropriateness of IoPPs either separately or in combination. From the case studies, there are three overall impressions. The first is that tolerant responses are much more prevalent than intolerant ones. The second is that civil society actors play an important role in responding to populists. The latter in particular applies to those cases where populist have gained power. The third is—perhaps unsurprisingly—that actors opposing populist parties tend to seek alliances with other types of actors. Civil society actors seek alliances with both political parties and representatives from public authorities and various kinds of political actors try to build alliances with EU actors. The theoretical discussions in the issue suggest tolerant responses are generally easier to justify than intolerant ones, kee** in mind that they should not always stand alone and that there are instances where intolerance is the appropriate response and where political parties and public authorities—for example at the EU level—ought to intervene more decisively to protect citizens’ democratic rights (Olsen 2022).