The Circular Economy in European Union Policy: Explaining an idea's success through policy learning

The circular economy (CE) was adopted in 2015 by the European Union (EU). Since its emergence, the CE has proved to be a remarkably powerful idea that has shifted the understanding of the economy, and consequently, it has shaped the EU's economic and environmental policies. The public policy literature theorises such shifts in collective understanding through the concept of policy learning, a process through which ideas are understood and adopted. Yet this literature lacks clarity on the factors that can explain policy learning within a policy community. We use the case of the EU's adoption of the CE to address this gap, exploring the factors that account for the EU's adoption of the CE from the policy-learning perspective. We show how actors in the policy community have constructed, championed, supported and pio-neered the CE and argue that these four factors have mutually reinforced each other, leading to policy learning and the wide acceptance of this idea within EU policy-making. Revealing these factors helps advance policy learning theory and contributes to the CE literature and environmental policy and governance literature more generally by furthering our understanding of how and why certain policy ideas are adopted.


| INTRODUCTION
The circular economy (CE) is a remarkably powerful idea that aims to redefine the relationship between the economy and the environment.
It proposes the maximisation of resource use within the economy and the minimisation of resource extraction and waste generation.Pearce and Turner first described the CE in 1990, coinciding with the emergence of similar ideas, policy strategies and business models inspired by the ideas of industrial ecology (Friant et al., 2020).The CE has interpretive flexibility, reflecting complex interactions between cultural and ideological differences, power relations and economic, social, and political interests.Initially, the CE was embedded within a set of reformist discourses that sought to reform and operate within the boundaries of capitalism (Blomsma & Brennan, 2017;Rödl et al., 2022).
Over time, it began to embody more transformational and ambitious discourses that sought to transform the socio-economic order to further sustainability goals (Bauwens et al., 2020;Friant et al., 2020).In the European Union (EU), the Commission and Parliament have embraced the idea of the CE and embedded it into policy, adopting a hybrid vision that more closely aligns with reformist and modernist visions of circularity (Alberich et al., 2022;Friant et al., 2021;Hartley et al., 2020).This article seeks to explain the CE's remarkable success through a case study examination of the process through which the CE became entrenched in EU policy.Ideas are learned and adopted by collectives of people.In the public policy literature, the shift in collective understanding can be theorised through the concept of policy learning.Policy learning explains how collective thinking can change among policy-makers to incorporate new ideas or beliefs (Dunlop & Radaelli, 2017).Policy learning focuses on the role of individual and collective actors, more specifically, the role of policy-makers in the adoption and reproduction of specific ideas in public policy (Dunlop et al., 2018).Hence, understanding how policy learning occurs allows us to understand how policy ideas such as the CE can be introduced within collective thinking and how they can also shape policy debates and, ultimately, policy outcomes.This paper contributes to this existing literature by creating a deeper understanding of how responses to important public issues such as the environmental crisis, social inequality and climate change are shaped by policy learning.
The CE provoked a change in how EU policy-makers made sense of the economy and solidified into a set of new policy strategies towards sustainability (Leipold, 2021).The CE did not emerge in EU policy until 2014, when the EU Commission (EC) opened up the discussion for a CE-based legislative package (Ekins et al., 2019).Since then, the CE has become the foundation of EU attempts to build a sustainable economy (Fitch-Roy, Benson, & Monciardini, 2020;Leipold, 2021).The CE's significant success as an idea that has been learned and adopted makes it an ideal case through which to examine policy learning and understand the processes involved.To date, the literature on the CE has focused on the degree of change implicit in the adoption of CE-based policies (Alberich et al., 2022;Fitch-Roy, Benson, & Monciardini, 2020) and the 'gap' between the promise of the CE and policy realities (Friant et al., 2021).Similar research has also focused on the expectations and limitations generated by CE discourses at the policy level (Hartley et al., 2020;Lazarevic & Valve, 2017).We build on this emerging body of work to understand how and why the CE has become so successful in EU policy.We ask what are the factors that account for the EU's adoption of the CE.By answering this question, we contribute to the literature on both policy learning and the CE.This paper is structured as follows: First, we review the literature on policy learning and its explanatory factors.Second, we explain the selected methods and approach to answer the research question.
Third, we explain the process of the CE'S adoption at the EU institutions and the four factors that account for its adoption.Fourth, we explain the positive feedback loops that reinforce the impact of the identified factors.Finally, we discuss the relevance and novelty of our findings within the policy learning literature and its implications.

| LITERATURE REVIEW
Policy learning theorises the change in collective understanding of reality and policy ambitions.This collective understanding of reality changes when policy actors adopt new ideas, beliefs, or interpretations of the world, influencing their political action (Heclo, 1974;Koebele, 2019;Leach et al., 2014;Pattison, 2018).Policy learning therefore affects policy actors' understanding of the world and their beliefs (Radaelli, 2009), which in turn, can influence their policy objectives (Dunlop & Radaelli, 2017;Jenkins-Smith et al., 2018).
Many scholars have studied the process of policy learning to understand its impact on public policy and what accounts for its success or failure (Dunlop & Radaelli, 2013;Harman et al., 2015;Lee & Van de Meene, 2012;McGowan, 2020).For instance, Dunlop and Radaelli (2013) identified how experts can have different degrees of influence on policy-makers, as they can act as teachers and be very influential, they can be partially influential, or they can be contested or even ignored by policy-makers.This factor, together with the tractability of a policy issue, was used to propose a classification for different modes of policy learning and the role of policy actors in inducing each kind of learning (Dunlop & Radaelli, 2013).This approach was replicated by other scholars such as Di Giulio and Vecchi (2019), Dunlop et al. (2020), Rietig (2018) and Trein (2018).
Di Giulio and Vecchi (2019) adopted a deductive approach to policy learning by focusing on the relationship between experts and policymakers.Other scholars have focused on how networks of experts can enhance their ability to bring knowledge to policy actors through expert certification (Polman, 2018) and how the ideological biases of policy actors can force them to renegotiate and reframe policy ideas (Leipold, 2021;Morf et al., 2023).
The literature on policy learning emphasises the relationships between experts and policy-makers and their ability to share knowledge and ideas (Dunlop, 2017;Polman, 2018;Trein, 2018).These groups of actors, also called epistemic communities, are networks of knowledge-based experts that have an authoritative claim to policyrelevant knowledge within their domain of expertise (Haas, 2007).
Although epistemic communities play a key role in inducing policy learning and in influencing the policy debate (Dunlop, 2017), policy can also be influenced by a wider array of actors beyond acknowledged experts (Milkoreit, 2017).
We propose an expansion of the existing focus on epistemic communities within the policy learning literature by adopting the notion of 'policy communities' (Skogstad, 2005).Policy communities include a wider set of relevant actors, public and private, that coalesce around a policy issue or that share a common interest in shaping its development beyond formal experts and policy-makers (Skogstad, 2005).
The concept of policy communities in policy learning research acknowledges the broader range of voices beyond acknowledged experts (Coleman et al., 1996;Skogstad, 2005).This approach allows us to adopt a broader perspective on policy learning by observing what factors account for policy learning within the broader policy community.

| METHODOLOGY
Between 2020 and 2021, the lead author conducted and analysed 48 elite interviews with different stakeholders involved in the adoption of the CE in the EU.These interviews included 20 policy stakeholders, 12 members of civil society groups, 10 business leaders, and 6 academics (see Table 1).The interviewees were selected on the basis of their first-hand knowledge and experience of debates, discussions and decision-making within the EU that led to the CE's adoption into policy.Finally, the lead author analysed the interviews using Gioia et al. (2013) to increase the qualitative rigour through careful investigation of all the collected information through an inductive approach.

| THE CE LEARNING IN THE EU
The CE became embedded within EU policy ambitions and discourses among policy-makers in particular and the EU policy community in general, resulting in the publication of the CE Action Plan of 2015 (European Commission, 2015) and its consolidation 5 years later with the publication of a second action plan in 2020 (European Commission, 2020).In this section, we discuss the process of policy learning that resulted in these CE policies, showing how four key factors shaped learning: (1) idea construction, (2) idea leadership, (3) idea empowerment and (4) idea pioneership, and their feedback loops.
Table 2 summarises these factors, providing a short description and explaining how the CE shaped policy learning.Table 3 summarises the positive feedback loops among these four factors which amplified their impact.

| The CE adoption process in EU policy
The CE started gaining the attention of policy-makers and stakeholders within the EU after 2010 because of the work of organisations such as the Ellen Macarthur Foundation (EMF).The EMF advocated for the CE by engaging with key members of the policy community, such as business leaders and researchers, and through the publication of relevant reports such as Towards the CE co-authored by McKinsey and the EMF (2012) (Interviews 1,38,46,48).These organisations and their reports led to the political construction and dissemination of the idea of the CE.The EMF first advocated for the CE among business leaders and other practitioners to build more sustainable practices in the economy.The idea of the CE steadily gained support among economic practitioners, and shortly after its creation, the EMF was invited to EU stakeholder consultations designed to shape EU policies.
The idea of creating a CE-based legislative package emerged from discussions held as part of the Resource Efficiency Stakeholder Platform.These discussions and the promotion work of organisations such as the EMF led to an empowerment of the idea of the CE as these organisations built relevant stakeholder support for the CE.As a result, the CE was first introduced in EU institutions in 2014 after the publication of the first CE legislative package called 'Towards a CE: a zero waste programme for Europe' (European Commission, 2014).It was proposed by the Barroso Commission through idea leadership (Interviews 1,18,20,21,25,29,31,38,46).This leadership led several practitioners to pioneer the idea of the CE and include the notion of circularity within new business models.
The Commission, led by Jean-Claude Juncker, withdrew the CE Package in December 2014 (Interviews 1,18,20,21,25,29,31,38,46,48), but this resulted in a counter-reaction from many members of the policy community, including business leaders that had pioneered the idea of circularity, policy representatives and members of civil society organisations that had supported it.As a result of this counter-reaction, the Juncker Commission had to review its position and started a negotiation process to create a new CE-based policy (Interviews 1,18,20,21,25,29,31,38,46,48).This led to the publication and implementation of the first CE Action Plan of 2015 (European Commission, 2015).In 2020, the next Commission published a second CE Action Plan (European Commission, 2020), consolidating the CE as the central idea that defines how the EU envisions its economy and how to achieve sustainable development.
The following section explains the factors in the successful adoption of the CE, not in terms of policy adoption but idea adoption.The CE is the case of an idea that was relatively unknown when it was first published in 1990, yet it has gained relevance and support since then to the point that this concept defines EU strategies for a sustainable economy.This section, thus, contributes to identifying the factors that account for the adoption of the CE through the lenses of policy learning and explains how these factors have impacted policy learning (Table 2).

| Idea construction
The first factor that shaped the CE's success was its construction.Idea construction is a process through which an idea is formulated by highlighting certain features and omitting others (Stephan, 2017;Williams & Sovacool, 2020) T A B L E 2 Explanatory factors of policy learning for the case of the CE in the EU.

Type of action How the CE influences policy learning
Impact on policy learning Impact on the policy process

Idea construction
Positioning of an idea among a set of values, interpretations and associations (Stephan, 2017).
Value alignment Aligns an idea with the values of influential actors and policymakers (Stephan, 2017).Policy-makers and other relevant actors are more likely to accept and adopt an idea if this is aligned with their values.
Idea construction determines how appropriate policy actors perceive a concept and the likelihood of them adopting it.

Problem fitness
Presents an idea as a solution to problems present in the policy agenda (McBeth & Lybecker, 2018).
Policy-makers and other relevant actors are more likely to accept and adopt an idea when this is presented as a solution to a preexisting problem.

Idea leadership
Action of individuals that seek to influence public thinking and transfer ideas into policy (Goyal & Howlett, 2018).

Coalition building
Strives to build and maintain coalitions of supporting actors (Witting & Dudley, 2019).Relevant actors who are persuaded to adopt an idea are encouraged to cooperate to promote it.
Idea leadership provides the agency necessary to promote an idea.Policy-makers are more likely to take action on a problem if there is a strong demand for a solution among citizens.

Idea pioneership
Practices that implement a certain approach directly in the economy (Berry & Berry, 2018).
Feasibility demonstration Provides evidence of policy feasibility and incentivises the replicability of such practices (Berry & Berry, 2018).Policy-makers are more willing to accept an idea if there is practical evidence of its feasibility.
Idea pioneership enables the creation of practical implementations of an idea before it is transformed into a policy.
and associations that are used to communicate the idea and allow its alignment with the pre-existing system of values and beliefs of relevant policy actors and collectives (Witting & Dudley, 2019).The CE was initially constructed with the publication of Economics of Natural

| The value alignment of the CE
The system of values that defines an idea is critical in determining its acceptance by policy actors and relevant stakeholders (Jenkins-Smith et al., 2018).At that time, the idea of sustainability was in tension with economic policy, as environmental policies were seen as restrictive, placing limitations on businesses and the economy.The EMF aligned the CE with a specific set of values to reach and previously excluded audiences, such as business leaders.The EMF framed the CE in such a way that it was seen to benefit the economy by avoiding costs in the consumption of materials and avoided environmental preservation as an explicit objective (Interviews 1,2,8,12,14,15,16,18,21,24,27,29,30).This framing of the CE was reproduced by the proponents of the CE and the members of the policy community that engaged with the EMF, such as business leaders and policy-makers.A scholar who participated in the Resource Efficiency Stakeholder Platform described this new framing: The whole narrative around the CE is that it is a new growth agenda for the EU.(…) The CE is a nice idea; you can't be against the CE.I mean, why would you be against the CE as a concept?
(Interview 1) By aligning the CE with economic values, the EMF expanded the range of stakeholders so that it was attractive to policy-makers and industry who had not engaged in environmental debates but who welcomed the opportunity for further industry-policy engagement.
Policy-makers noted that industry welcomed the idea and sought to engage with it.Importantly, one of the most attractive qualities of the CE was the way in which it was perceived to create a winwin narrative with few, if any, losers (Interviews 1,10,16,19,20,22,23,26).Although some productive sectors may be negatively affected, in the long term, the CE was seen to enable the generation of jobs and growth, offsetting the potential job losses caused by this transition.Such win-win narratives minimised opposition and widened the range of supporters to include powerful industry actors.

| Problem fitness
Problem fitness refers to the degree to which an idea is perceived to be a solution to existing policy problems (McBeth & Lybecker, 2018).
Although the EMF primarily framed the CE as an idea capable of economic reform, it also presented it as a policy solution to the existing and worsening environmental crisis.The degree to which the CE is perceived to be able to address these environmental problems is critical as EU policy-makers face increasing pressure to find new pathways to develop the economy in sustainable ways (Interviews 1,2,4,7,12,15,17,18,20,28,30,33,36,38,40,46).The EMF presented a CE narrative that conciliates sustainability concerns and the perpetuation of economic growth ( Interviews 1, 2, 4, 6, 10, 16, 17, 19, T A B L E 3 Positive feedback loops among the four policy learning factors.

Idea construction Idea leadership Idea empowerment Idea pioneership
Idea construction Attracts support from individuals and policy leaders who want to champion policy change.
Attracts support from powerful stakeholders.
Attracts interest from practitioners and inspire them to incorporate and pioneer a policy idea.

Idea leadership
Strategically reframes how the idea is constructed to attract more support.
Mobilises and creates coalitions of supporters to support a policy idea.
Collaborates with practitioners and encourage them to pioneer a policy idea.
Idea empowerment Strategically provides support for the ideas that fit their pre-existing beliefs and biases.
Empowers and endorses policy leaders that defend their pre-existing beliefs and biases.
Generates the demand, support, and acceptance of practices.
Idea pioneership Provides proof of the feasibility of certain ideas.
Provides endorsement of and validation for certain policy initiatives.
Provides endorsement of and validation for certain policy initiatives.23,30,33,36,47,48).This conciliation enabled a narrative that promised to address the environmental emergency and was key for its adoption.A policy-maker from an EU member state described this problem fitness as: The CE is a big umbrella for all of this climate action and all that happens on the climate side.We have quite heavy targets on what we have to achieve to be climate neutral by 2050.Clearly, the CE is part of that.
(Interview 32) This framing is independent of the debate on the compatibility of addressing the environmental crisis with the maintenance of economic growth.Although there is a scholarly debate that highlights the need to ditch economic growth to prevent irreversible environmental damage (Feola, 2020;Hickel & Kallis, 2020), this debate is not reproduced in the policy sphere as mainstream narratives aim to compatibilise growth with sustainability.
Idea construction determines how actors in the policy community perceive an idea and the likelihood of them adopting it.In this case, policy-makers and other relevant actors were more likely to accept and adopt the CE if it was aligned with their values and presented as a solution to a pre-existing problem.We found that actors framed the CE as an economic strategy that is centred around the idea of reforming the economy to maximise benefits and minimise losses by changing the way materials are managed in the productive cycle.Further, it promised to address the need to reduce the environmental impact of productive activity.This framing allowed the for the broad engagement of relevant industry stakeholders and constructed the CE as a strategy compatible with the current economic and political power structures, presenting low social and economic transitional costs.8,18,20,21,25,29,38).Such coalition building was critical for policy learning as it enabled powerful and relevant policy community's members to support and adopt the CE and promote it through their own networks.

| Policy introduction
Policy introduction involves policy leaders translating the idea of CE into a political objective and placing it on the political agenda.The EC maintained the mandate to develop the CE in the EU, and it remains one of the EC's main priorities (Interviews 1,15,17,18,20,25,26,28,30,32,36,38,45,48).
Idea leadership refers to those policy actors that provide the necessary agency to promote the adoption of a concept or idea.In this case, policy-makers and other relevant policy community members are more likely to accept and adopt the CE in the presence of a skilful leader that is willing to engage them.We found that policy leaders were critical in engaging stakeholders to support the CE and introducing the debate on the CE to the political agenda.This leadership enabled political support for the CE and opened up a debate on the need to build CE-based policies in the EU institutions.

| Idea empowerment
The third factor that conditioned the adoption of the CE was the support and empowerment that emerged around it.Idea empowerment is the combined pressure exerted by social actors to induce policymakers to make certain decisions, for example, to adopt certain policies or address certain issues (Weible & Ingold, 2018).Policy-makers within EU institutions received external pressures to shape the scope, timing, approach, and ambition of CE policies.This pressure was exerted in three ways, through professional advocacy lobbies, consultations with stakeholder groups, and by broader social movements and citizens actions.These three kinds of pressure promoted policy learning by empowering the CE but also by ensuring it materialised into policy.

| Professional lobbying
Lobbying by professional advocacy organisations can mobilise skilled Professional industry lobbyists possess more resources to advocate for their interests in comparison to competing organisations such as environmental organisations and labour unions, leading to an overrepresentation of industry interests in engagement activities, such as their presence in stakeholder platforms or policy discussions, and more influence in such forums (Interviews 11,24,25,29,30,31,34,36,40,42).Policy-makers within EU institutions are fairly receptive of industry lobby groups as they provide expertise and feedback to help policy-makers craft policies (Interviews 22,25,29,36).One interviewee who was present in these meetings as a journalist noted: Look at some of the working groups that the Commis- The businesses that were for (the CE) then reacted very badly when the EC dropped the CE idea, and they forced the EC to take it up again.So that was a really interesting phenomenon.Although there had been some business lobbying against the Potočnik plan, actually, more businesses were in favour of it, and when the new Commission dropped the action plan, they protested very loudly along with all sorts of other people, and even national governments protested.
(Interview 25) Consequently, the Juncker Commission had to rectify the situation and quickly changed its narrative and promised a new CE strategy for the EU (Interviews 1,18,20,22,24,25,29,31,33,34,36,38,39,42,44,47).This stakeholder pressure led to new negotiations between the EC and the Resource Efficiency Stakeholder Platform and the publication of the first CE Action Plan in December 2015.

Such advocacy from stakeholder groups within the policy community
to recover what they saw as the critical aspects the CE in 2014 is an example of how public pressure, especially from powerful stakeholders, is critical to idea empowerment.This pressure empowers an idea and enables it to shape public policy.Stakeholder engagement around the CE was fostered by the advocacy tasks of the EMF, promoting the CE and engaging business leaders and society in general, and Potočnik's work creating engagement within the EU institutions and within the Resource Efficiency stakeholder platform.

| Social movements and citizens
Social movements and citizens from outside the policy community have the ability to influence the policy sphere by mobilising or protesting against particular elements of the social order or policies (Kübler, 2001).The difference between the pressure from social movements and citizens and that from industry lobbyists and stakeholders is that the latter aimed directly and specifically to influence policy-makers, while pressure from citizens is vaguer, and it generally comes in the form of generalist public concerns towards great issues such as sustainability.
Although EU institutions have promoted sustainable strategies for a long time, societal pressure to improve the EU's sustainability performance has increased in the last few years.In the interviews, EC policy-makers acknowledged the role of scientific voices in presenting evidence and insisting on the need to address the environmental crisis (Interviews 23,24,26,27,46).Policy-makers and key actors within the EU acknowledged an increase in citizen pressure to adopt sustainable policies, especially in the last few years, with the emergence of new citizen platforms, such as Fridays for Future and Extinction Rebellion, and the increase of electoral support for the Green parties across the EU.As a policy officer from an NGO explained: The new Commission (…) made the European Green Deal a priority, (…) which is a big change from the previous Commission, which had jobs and growth at the core.And yeah, it came from the whole public pressure like the schools, and Fridays for Future, all the school children out on the streets protesting and Extinction Rebellion getting really big.So, I think that definitely had an influence on the EC making the European Green Deal a priority.
(Interview 36) Ideas are empowered through the pressure or support exerted by actors to induce policy-makers to adopt an idea.In the case of the CE, policy-makers and other relevant actors were more likely to accept and adopt the CE if it received explicit support from different members of the policy community as well as by citizens and social movements, but this pressure can also influence how the CE is being materialised into policy by influencing policy scope, timing, approach and ambition.In this case, professional industry lobbyists pressured policy-makers to weaken or remove the CE from policy, stakeholder groups built by idea leadership subsequently advocated for the CE's re-adoption, and citizen and social movement pressure more broadly focused attention on the need to address the environmental emergency and mitigate issues such as climate change and pollution.These different sources of political pressure provided critical support to empower the CE and promote its adoption in EU policies.

| Idea pioneership
The last factor that emerged during the process of adoption of the CE is idea pioneership, and the set of practices by practitioners, mostly businesses, that started including the idea in their products and services, transforming the CE from an economic idea to an economic reality on a small scale.Idea pioneership is the set of practices that implement a certain approach directly in the economy.In this case, the presence of pioneering practices led to the start of the implementation of CE-based practices in the economy.These economic practices enable policy learning by providing practical proof to policy-makers of the feasibility of a policy idea.Some scholars also identified the role of existing practices in promoting learning (Berry & Berry, 2018).These practices not only provide evidence of the feasibility of a certain idea but also provide an endorsement of certain practitioners of this idea (Interviews 1,7,8,14,15,25,26,29,30,32,33,42).
Economic practices allowed policy-makers and policy representatives to understand and be convinced of the feasibility of a CE strategy for the EU in the availability of cases where the industry is already implementing CE practices (Interviews 7,21,25,29).Large corporations developed cases to provide evidence of the feasibility of the CE.One prominent case was the Phillips lightbulb, which was frequently mentioned by interviewees.Phillips proposed a business case where it would directly sell light instead of lightbulbs, maintaining the ownership of lightbulbs and hence, the materials used to manufacture them, and assuming the responsibility to repair or recycle them.These

| Positive feedback loops
The four factors described above influenced the understanding of the CE among policy actors and persuaded them to adopt a very specific version of the CE.However, these factors have also reinforced each other, creating a set of positive feedback loops that amplified the influence of the identified factors on policy-makers and can help explain the success of these factors in creating policy change (see Table 3).
Idea construction affects policy leaders as the alignment of the CE with the values implicit in idea construction encourages policy leaders to support the CE (Interviews 17,20,23,25,29,40,48).Similarly, the framing of the CE has attracted support from advocacy groups able to support the CE (interviews 1, 25, 36, 40).The practices of pioneers are equally affected by idea construction, as economic actors are likely to integrate CE practices if these align with their values and interests, enabling the reproduction of the CE on a practical scale (Interviews 1,8,10,13,15,21,22,30,39).
Idea leaders can strategically mobilise resources and persuade stakeholders to mobilise their resources to support policy ideas.Policy leaders can strategically reframe the CE to adapt it to the set of values of powerful and influential policy actors (Interviews 20,(29)(30)48).
Also, they can act as leaders and enhance public pressure to create and amplify public support around the concepts that they want to promote (Interviews 1,18,29,38).Finally, policy leaders collaborate with economic actors, mobilising them to pioneer CE-based practices (Interviews 1,7,22,32,33,48).
Idea empowerment is a critical factor in promoting ideas such as the CE.Idea empowerment can act selectively, influencing or supporting certain aspects of an idea (Interviews 1,21,34,36,46,47).Also, it can influence policy leaders by providing visible support and endorsement of their proposals and even providing resources for them (Interviews 1,3,18,23,26,29,31,35,36,38).Finally, citizen engagement also incentivises practitioners to pioneer in generating CE practices, as they generate a demand for and an idea of the public appetite for such practices (Interviews 15,21,34).
Finally, idea pioneership provides evidence of the CE's feasibility and endorsement from economic actors and practitioners.The benefits of this endorsement for a specific version of the CE are based on supporting new business opportunities and generating growth (Interviews 11,24).But also, it benefits both policy leaders and public pressure groups, validating their proposals to adopt the CE (Interviews 1,7,13,15,21,25,29,30,42). Additionally, the presence of economic practices encourages citizen support for CE adoption as new policy actors and support groups become persuaded of the appropriateness of the CE (Interviews 12,16,30,32,33,40,42).

| DISCUSSION
This article shows the CE's adoption in the EU as a case of policy learning.This research provides a framework of four factors that are critical to assessing the potential of a concept to be successfully learned by policy actors.This framework contributes to understand how concepts and ideas that are traditionally found in the realm of academic debate can be upscaled to other spheres, such as the policy sphere, the sphere of civil society and the corporate sphere, allowing us to address critical societal challenges such as the growing social inequality and the environmental emergency.
The inclusion of the concept of the policy community within this research (Skogstad, 2005) and the adoption of an inductive approach to this case of policy learning allowed us to identify new factors that account for policy learning.Consequently, we propose new factors to explain policy learning (Table 2).In idea construction, we found that the values of policy ideas succeed when accompanied by the expectations of these ideas to solve policy problems.We also identified two functions of idea leaders: the opening of specific policy debates around certain ideas and the creation of support coalitions around such ideas.In the case of idea empowerment, we distinguished between three different kinds of support for policy ideas, from general citizen and social movement support to professional advocacy and the support of acknowledged stakeholders and policy-makers.
Lastly, we showed how economic practitioners play a role in the policy debate by pioneering and implementing certain ideas.
The CE adoption can be seen as a conscious decision of the EU to fulfil a set of economic expectations (Hartley et al., 2020;Lazarevic & Valve, 2017;Pinyol Alberich, 2022).Yet, the predominance of EU policy-makers that are ideologically aligned with ecomodernist positions, along with the interests of powerful advocacy groups and influential businesses, specifically explains the enactment of a modernist version of the CE.This contrasts with the lack of support to more ambitious and radically transformative versions of the CE that are also present at the EU policy debates (Leipold, 2021;Palm et al., 2021).
The factors that explain learning are not new in the literature on public policy.Other scholars have also identified how idea framing plays a key role in how groups of policy actors interact with policy ideas and concepts, either adopting them or disagreeing with them (Ballew et al., 2019;Lakoff, 2010;Liou et al., 2021;Sanderson et al., 2018).Others, such as Kingdon ( 2013), and Jenkins-Smith et al.
(2018), highlighted the important role of ideas in policy and the coalitions of policy actors who carry these ideas forward into policy, findings consistently identified by other learning scholars (Grönholm & Jetoo, 2019;Morf et al., 2023).Popp et al. (2011) andSmith (1990) also describe how idea empowerment can influence and pressure policy-makers to raise awareness about a specific topic and create an acceptance or rejection of a specific idea, how powerful actors can inhibit learning (Johannessen et al., 2019) and how nonstate actors can empower learning (Nath & van Laerhoven, 2021).Finally, some scholars also identified the role of existing practices in promoting learning (Berry & Berry, 2018), although the role of corporate actors in creating such practices still remains under-researched.In bringing these factors under the umbrella of policy learning, we extract new insights.First, we explain the role of the four factors in enhancing policy learning.For instance, the factor of idea construction explains how the implicit set of biases and values within the framing of policy knowledge is critical to explaining why policy community's members are likely to accept this knowledge.Other elements, such as leadership, also play a critical role, as policy leaders provide the necessary agency to open up certain debates within the policy sphere and can empower certain ideas.Second, we have found how new actors, such as pioneers, who have traditionally been overlooked in the public policy literature, have a critical effect on policy learning.Third, we have identified how policy learning is a deeply politically biased phenomenon, as policy actors tend to learn those ideas that confirm their preexisting set of values.Fourth, we have identified how these factors not only contribute to policy learning but also reinforce each other, maximising their effect in the policy arena.
A second contribution of this research is the inclusion of the concept of policy communities in the policy learning literature (Skogstad, 2005).This approach allowed for the identification of a more diverse set of factors that account for learning beyond the relationship between policy-makers and experts.These factors represent a novel contribution to the previous literature from Dunlop and Radaelli (2013) as we expand on the nature of learning beyond the relationship between experts and policy learning to include new factors such as the values and framing of the ideas to be learned, the role of leaders and coalitions of actors to promote specific ideas and the role of practitioners in pioneering certain ideas.This comes at a time when there is renewed emphasis being placed on collaborative and co-produced forms of policy-making which demand consideration of a plurality of actors (Grönholm & Jetoo, 2019;Harvey et al., 2019;Nath & van Laerhoven, 2021).A plurality that can also build a more nuanced vision of the CE that incorporates ideas such as the sharing economy (Henry et al., 2021), or a steady state economy (Daly, 2014).
In this sense, the findings of this paper can inspire strategies to empower new and more transformative visions of the CE.These However, our contribution has limitations.The choice of using a single case study to theorise policy-learning has inherently limited validity (Flyvbjerg, 2006).The second limitation is the limited scope of conducted interviews.Although we carefully selected the interviewees to obtain a representative vision of the policy community, it was not possible to access certain actors, such as the policymakers that opposed to the CE adoption or actors that support more transformative changes at the EU.In this sense, further research could specifically aim at understanding the role of these actors and their perspective on the CE adoption.

| CONCLUSION
These new factors provide a more comprehensive approach to addressing policy learning in future research.Namely, idea construction clarifies the role of ideas in contributing to policy learning.The factors of idea leadership and idea empowerment show how policy actors play a critical role in influencing policy learning.Also, the identification of idea pioneership represents a relevant factor for policy learning that is still relatively under-researched.This factor has the potential to open up a new perspective on policy learning as it relates to how practitioners and other actors that are not policy-makers can influence policy learning from their position as practitioners.This research also identifies the presence of positive reinforcing loops among the identified factors that reinforce their effect on policy learning.Consequently, future research can build on the constraints and potential of the identified factors and feedback loops between them.Especially the role of practitioners in pioneering policy ideas, represent a valuable new avenue for research, as their contribution to policy learning remains under-researched.
Resources and the Environment byPearce and Turner (1990) and subsequently by consultancy firms such as the EMF and McKinsey, without the influence of foreign countries.The EMF has worked since its creation in 2009 on the construction of the idea of the CE by reformulating and promoting it to appeal to business leaders, mainstream civil servants, and policy-makers.Also, the EMF and McKinsey published the report 'Towards the CE' in 2012, where they formulated a definition of the CE and promoted its adoption.The EMF framed the CE in two ways; (1) aligning it with a set of values (value alignment), and it avoided potentially difficult environmental and sustainabilityrelated jargon.Then, (2) the EMF framed the CE as a solution to the environmental crisis (problem fitness).

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Idea leadership' refers to the action of individuals that seek to influence public thinking and transfer ideas into policy(Goyal & Howlett, 2018).Policy leaders are key actors with the agency and capacity to influence public thinking or policy outcomes to promote a set of ideas or goals(Jones et al., 2009;Witting & Dudley, 2019).In the case of the CE, policy leaders emerged to champion the CE and promote it among the policy community, including networks of practitioners, policy-makers and academics to raise awareness and support.Ellen MacArthur, through the EMF, and the former EU Commissioner, Dr Janez Potočnik, were two of the most notable leaders that promoted the adoption of CE-based policies in the EU.These leaders involved themselves with two tasks: (1) coalition building, to build and maintain coalitions of supporting actors(Witting & Dudley, 2019) and (2) policy introduction, to enable debate about an idea within the policy community(Weible & Ingold, 2018).This idea leadership was critical to generating support among policy-relevant and influential actors for the introduction of the CE to the political agenda.The importance of Potočnik in doing this task of policy introduction from his position as Environment Commissioner was key, as one of the interviewed policy-makers stated: I think having Mr Potočnik was important, very important.I studied history, and I was always against the concept of the history of great men and everything being defined by people in positions of authority.But it was important that he was an economist.(…) What he picked up on was the need to move away from a legislative approach to environmental policy.(Interview 29) 4.3.1 | Coalition building around the CE As two powerful policy leaders, MacArthur through the EMF and the former EU Commissioner, Potočnik, actively brought together members of the EU policy community to explain the CE and foster its support.In 2009, the EMF created the CE100, a set of 100 businesses that supported the CE, expanding the CE policy community with the inclusion of corporate stakeholders.The CE100 was crucial in providing support for the promotion of the adoption of the CE (Interviews 1, 7, 9, 13, 29, 33, 47).MacArthur played a key role in advocating for the CE among business leaders and other key members of the policy community.In 2012, MacArthur was personally invited to participate in the discussions of the Resource Efficiency Stakeholder Platform to discuss the development of resource efficiency policies by the EU.In these meetings, she advocated for the adoption of CE-based policies to meet the EU's ambitions in resource use and to build more sustainable practices in the economy.Potočnik, also advocated across the EU to build support for the adoption of CE-based policies.As a consequence of MacArthur and Potočnik's advocacy work, members of the stakeholder platform, including members of the European Parliament, representatives of Member States, NGOs, business representatives, workers' unions and academics, discussed together the convenience of adopting the CE at the EU level.Consequently, those members of the policy community became key supporters of the CE (Interviews 1, Potočnik, was a key leader in this regard, translating political support for the CE into the publication of the CE Package of 2014.The Resource Efficiency Stakeholder Platform, with MacArthur's involvement, suggested developing a new generation of CE inspired resource efficiency policies.Potočnik agreed with this suggestion and advocated the development of a legislative package inspired by the CE, leading to the publication of the CE Package of 2014.This was the first time the CE had been the central idea in an EU policy.Once Commissioner Potočnik's mandate ended, the CE was already on the EU's political agenda, where it has remained.This step was critical for the development of the CE, as Potočnik's work within the EC transformed the CE from an economic idea to a specific policy proposal and opened up the CE discussion within the EU institutions. actors and their discursive abilities to influence the EU policy-making process regarding the CE(Fitch-roy, Fairbrass, & Benson, 2020;Fligstein, 2001).The influence of professional lobbying became visible after the EC published the 2014 CE legislative package.In December 2014, the newly appointed EC led by Jean Claude Juncker ditched the CE legislative package of 2014 after the lobbying of large corporate professional organisations, such as BusinessEurope(Balch, 2014;Crisp, 2014).Although this decision was later changed, it illustrates the influence of industry's professional lobbyists on the decisionmaking process, an influence that remained throughout the design of the CE-based policies.Industry lobbyists sought to shape the framing of CE policies to align them with existing economic and political power structures with two important consequences.First, framing the CE in terms favourable to business interests makes this concept more appealing to the current powerful vested interests in the EU and requires low social and economic transitional costs.Second, it prevents the CE transition from achieving transformational change in the current economic system which was desired by those championing the idea.The role of industry lobbyists in preventing such change was acknowledged by a policy-maker within the EC: Among the industry associations, it is a little bit more difficult (to promote higher standards) for the reason that associations represent all their members, and among their members, there are those who have an interest in pushing the bar high, and there are other companies who have interests in keeping the bar as low as possible.Of course, the association has to find a compromise between these two positions.(Interview24) sion has.Civil society has maybe two or three seats, and there are like 20 business seats.(…) Business is certainly overrepresented.(…) I mean, it's crazy how many lobby groups are there.There is a lobby group for everything like with the single Use Plastics Directive there was a lobby group specific for balloons speaking up because they were going to ban the plastic sticks that you use to hold a balloon with.(Interview 31) 4.4.2| Advocacy from stakeholder groups When the Juncker Commission initially ditched the CE Package in response to intense industry lobbying, many stakeholders, including Member States, NGOs, and some leaders of big companies, such as Phillips, Unilever, Michelin, and Suez, reacted to this withdrawal by expressing their disappointment and opposition to the decision.As one participant in the Resource Efficiency Stakeholder Platform stated: cases were used as examples to explain the nature of the CE and its feasibility to policy-makers.When the EC came out with the Action Plan, many people in different countries, when I was talking about the CE, they said, do you have any examples?And I was explaining or using, for instance, the Philips lighting example or bulb lights as examples.Everybody recognised the company, and for the first two years, I was mostly referring to existing group business models.(Interview 30) These kinds of practices were key, especially to convince the most conservative members of the European Parliament and policymakers within Member States.After the first CE action plan was introduced in 2015, there were still conservative voices concerned with regulation that could negatively affect the economy.The fact that many industry stakeholders not only promoted the CE but also pioneered the application of CE practices is a key factor that contributed to easing any remaining opposition to the CE over time, especially among conservative sectors (Interviews 25, 29-30).
findings can also contribute towards a theory of how more transformative constructs and ideas that are often marginalised or disregarded in political and governance arenas may be fostered, particularly those ideas that offer solutions to the current ecological crisis.They clarify how professionalised advocacy, policy leaders' preexisting values, and the influence of economic actors reinforce less transformative visions within these arenas.The findings also show how social movements and citizens can bring attention to environmental issues, counteracting these powerful forces and creating windows of opportunity for more ambitious and transformative change.
. It involves a set of values, interpretations T A B L E 1 Interviewees categorised by affiliation.