Circular economy: A new research field?

Action to pursue the circular economy (CE) transition is burgeoning in the government and the private sector. Does this action signal that CE is a distinct field of research with a unique disciplinary identity? This article argues that CE has reached field status, through its own epistemic communities characterized by increasingly shared methodological perspectives and normative ideals, and through institutionalized knowledge development through research journals and authority structures. The recent growth of CE research points toward more contextualized and nuanced operationalizations of the concept, evidence that the field is approaching a threshold state of maturity. Drawing on observations from academic literature and discussions with researchers and experts, we trace the process by which CE has arrived at the status of a field. The article concludes with reflections on research directions.

that these are not free of controversy and debate.Additionally, we observe that epistemic communities dedicated to CE have emerged through conferences, scholarly societies, and other knowledge exchange platforms.These developments suggest that the CE concept is mature enough to be considered a distinct field of scholarship.
Our argument builds on a long history of research that contemplates the threshold at which emergent ideas become a field or discipline (Tight, 2020).Examples of eventual fields undergoing such analysis are English (Randel, 1958), statistics (Minton, 2012), cultural studies (During, 2006), innovation studies (Fagerberg & Verspagen, 2009), nursing education (Findlow, 2011), health and marketing (Stremersch, 2008), international business (Michailova & Tienari, 2014), and gender studies (Rollmann, 2013).We argue that it is time for CE to receive the same analysis.The remainder of this article is structured as follows: Section 2 outlines our core assumptions.Section 3 outlines our observations and the degree to which they demonstrate CE as a field of scholarship and its level of institutionalization. Section 4 concludes with a broader reflection about research directions.

BACKGROUND ASSUMPTIONS
Production of formal knowledge in the academy has traditionally been organized along the boundaries of distinct disciplines.Within these disciplines emerged sub-disciplines cross-cutting in concept and scope (van den Besselaar & Heimeriks, 2013;Whitley, 2000).Whereas some general realms of scholarly inquiry (e.g., mathematics) have existed for centuries, the modern notion of a discipline as a ring-fenced, coherent, and institutionalized body of knowledge and community of research emerged only in the early 18th century (Finkelstein, 1997).The earliest disciplines evolved over time, while new and "offshoot" disciplines emerged when "parent" disciplines reached a threshold level of breadth and complexity (e.g., statistics, originally a sub-discipline of mathematics; Tight, 2020).In response to evolving societal interests, other disciplines faded in relevance (e.g., theology; Krishnan, 2009).
The academy's organization into distinct disciplines has been said to breed a dogmatic and siloed research culture.A principle focus on basic (nonapplied) research has also drawn criticism.According to Whitley (2000, p. xx), disciplines have been defined by their "purely intellectually driven research without any consideration of useful outcomes."Partly in response to such criticisms, quasi-disciplines or "research fields" have emerged in parallel to traditional disciplines, weakening the epistemic and territorial hegemony that academic elites (i.e., long-serving faculty entrenched in their disciplines) have held over their respective fields (Whitley, 2000).Academic disciplines are now characterized by increasing interdisciplinarity and epistemic and methodological diversity, while in some cases emphasizing practical applicability and a "mission orientation" (see Ledford, 2015;Okamura, 2019).

CIRCULAR ECONOMY AS A FIELD OF SCHOLARSHIP
Definitions abound regarding what constitutes an academic discipline versus a field (Ehrenfeld, 2004;Goodchild, 1991;Krishnan, 2009;Squires, 1992).While both can share conceptual and institutional footings, "the field is not, or at least not yet, [as] organized as [. . .] disciplines" (Fagerberg & Verspagen, 2009, p. 218).We observe Ehrenfeld's (2004) definition of fields, which consists of four criteria: (i) foundational beliefs and concepts that lend a common meaning to all players; (ii) practical resources like textbooks and standard tools; (iii) authoritative structure maintaining quality and (some) conceptual coherence; (iv) community of actors participating in the aforementioned activities.In this section, we consider CE through the perspective of these four characteristics (summarized in Table 1).The section concludes with a brief discussion about the institutionalization of CE as a field.

3.1
Shared beliefs and concepts Ehrenfeld (2004, p. 826) states that an academic field must be rooted in "a set of foundational beliefs that lend a common meaning to all players [. . .] and allow communication across boundaries of the field."It is well documented that CE is a contested idea (Blomsma & Brennan, 2017;Korhonen et al., 2018).Kirchherr et al. (2017) distinguish among sources of this contestation: core principles (the "how" of CE), aims (the "why" of CE), and enablers (the "what" of CE).While some recent scholarship recognizes diversity in beliefs and concepts regarding CE (Calisto Friant et al., 2020;Leipold et al., 2021), we argue that scholars have begun to agree about CE's core principles (sufficiency/"reduce" as a core strategy; systemic change) and core enablers (business models, policies, and consumers).At the same time, there remains some contestation regarding CE's aims (e.g., partial sustainability, or reconciling economic growth and environmental sustainability).
Early CE literature either portrayed CE as both an ends and a means or ignored what the adoption of circularity principles was intended to achieve altogether; Kirchherr et al. (2017) found that only 12% of the 114 CE definitions examined mentioned the concept of sustainable development.
However, we observe that the literature has begun to view CE as an instrument to achieve sustainability-apparent in the increasing use of the term "sustainable circular economy" (Jaeger-Erben et al., 2021;Velenturf & Purnell, 2021) and in the high citation count (over 5000 in Google Scholar) of an article by Geissdoerfer et al. (2017) exploring CE as a paradigm for sustainable development.
Convergence in the CE-sustainability narrative can be found, for example, in calls for a sufficiency-based CE (e.g., Bocken & Short, 2020;Bocken et al., 2020); this idea considers how the private sector, public sector, and consumers can collaborate on CE initiatives that ensure that consumption and production do not exceed planetary boundaries (O'Neill et al., 2018).Other examples include the salience of the "reduce" concept and the idea that CE implementation necessitates a systemic shift.The systems perspective emerged from an early contribution by Boulding (2013) concerning "economics of the coming spaceship earth"-often viewed as a foundational article in CE literature (Geissdoerfer et al., 2017;Kirchherr et al., 2017).
Examples of later CE literature adopting the systems perspective are Even with this increased focus of CE literature on sustainability, we maintain that environmental and economic sustainability is the primary topic, with less attention on social sustainability (Amorim de Oliveira, 2021; Kirchherr, 2021a;Mies & Gold, 2021;Repp et al., 2021).In this way, the literature demonstrates a preference for "partial sustainability."Regarding environmental and economic sustainability, the mainstream view appears to remain that a de-coupling of environmental degradation and economic growth is possible, but a smaller and more critical line of scholarship challenges this view (Corvellec et al., 2021;Hobson & Lynch, 2016;Kirchherr, 2021b;Lazarevic & Valve, 2017;Merli et al., 2018).Even scholars who argue that de-coupling is possible often acknowledge that circular practices do not necessarily enhance sustainability and that "circular rebound" 2 may occur (Blum et al., 2020;Leipold et al., 2021;Masi et al., 2017;Urbinati et al., 2019;Zink & Geyer, 2017).
Other CE enablers providing grounds for shared beliefs and concepts are business models and policy intervention.Circular business models have emerged as a commonly discussed enabler and one of the most vibrant sub-fields of study within CE literature (Bocken et al., 2016a;Geissdoerfer et al., 2020;Ünal et al., 2019;Urbinati et al., 2021).According to Kirchherr et al. (2017), a "CE understanding lacking business model is one with no driver at the steering wheel" (p.228).An additional enabler receiving increasing attention is public policy, with scholars arguing that CE transition requires direct government intervention on regulation, infrastructure, education, and other factors (Hartley et al., 2020;McDowall et al., 2017;Milios, 2017;2021).Regarding the role of consumers in CE transition, some literature has emerged (Coderoni & Perito, 2020;Kuah & Wang, 2020;Testa et al., 2020), but this enabler remains under-researched and thus no consensus seems to have formed.

Practical resources
The second criterion for a field is the presence of practical resources, including standards-based guides, handbooks, tools, and metrics (Ehrenfeld, 2004).Efforts to create and consolidate resources across academia, companies, and supporting organizations suggest that CE is progressing into a field.CE-related handbooks and guides have proliferated in recent years (Table 2), many of which are written by practitioners (e.g., Lacy et al., 2020;Stahel, 2019) even as most are printed by academic publishers.This trend confirms the argument by Corvellec et al. (2021) that the CE discourse is driven by practitioners-atypical of most fields related to sustainability.
Tools aiding CE implementation, including assessment of circularity performance, are not commonly used by companies or public sector entities (Sassanelli et al., 2019).However, the topic has seen growing research attention (Corona et al., 2019;de Pascale et al., 2021;Kristensen & Mosgaard, 2020;Moraga et al., 2019;Saidani et al., 2019;Sassanelli et al., 2019;Scarpellini et al., 2019), suggesting that some conceptual convergence may eventually arise.CE indicators, as a subset of tools, have been proposed at the micro-, meso-, and macro-levels, with micro-level indicators around circular business model implementation the best developed (de Pascale et al., 2021;Kristensen & Mosgaard, 2020).Tools for meso-level implementation of CE have received the least attention in scholarship and practical application (Ghisellini et al., 2016;Scarpellini et al., 2019).

Authority
A field must entail an "authoritative structure maintaining quality and [some] conceptual coherence," and academic journals typically play this role when a field of scholarship emerges (Ehrenfeld, 2004;p. 826).The Journal of Cleaner Production is currently a leader in volume of CE research published (Centobelli et al., 2020;Merli et al., 2017), although the journal is not dedicated specifically to CE.Several journals have re-branded toward CE, including the Journal of Industrial Ecology-which states that it "publishes sustainability and circular economy research" (JIE, 2021) even as its

Community of actors
Shared beliefs and concepts, practical resources, and authorities are all developed and maintained by communities of actors, manifest in part through issue-specific conferences and societies (Ehrenfeld, 2004).Ehrenfeld's (2004) example is the International Society for Industrial Ecology, which was instrumental in establishing a community of actors around industrial ecology and advancing the emergence of the field.CE is now a prominent topic at various disciplinary conferences, while conferences dedicated specifically to CE are increasingly common.Further, the International Society for Circular Economy (IS4CE) was launched in 2020, providing additional indication of CE as an emerging field.
CE is now often the topic of dedicated panels at major academic conferences, including the Annual Meetings of the American Association of Geographers and the American Economic Association.Conferences dedicated to CE have recently been held in Europe, Latin America, the United States, Australia, and Asia (Table 3).Notably, almost all of these conferences bring together academics and practitioners, but the focus is primarily on application.Our discussions with experts suggest that this phenomenon is unique to CE in comparison to other sustainability-related fields.
This phenomenon may also reflect the highly applied nature of the field, suggesting that theoretical novelty is scarce-particularly in comparison to sustainability-allied disciplines like economics, public policy, political economy, and others.Possibly due to the dominance of practitioners, CEdedicated conferences and their keynote speakers tend to be well-funded, according to experts with whom we held discussions.This high level of resourcing seems to be a peculiar characteristic of the CE field, given that funding for sustainability-related research has traditionally been rather meagre (Fritz & Binder, 2020;Rau et al., 2018).
The presence of societies also indicates the growing maturity of the field.For example, the International Society for Circular Economy (IS4CE) is a new academic society focused on CE, holding its inaugural conference in July 2020.While the IS4CE may thus far be the most ambitious effort in academia to foster a CE community of actors, an equivalent effort among practitioners may be the Platform for Accelerating the Circular Economy (PACE)-launched in 2018 as a collaboration among the World Economic Forum, World Resources Institute, Philips, Ellen MacArthur Foundation, United Nations Environment Programme, and over 40 other partners (IS4CE, 2021).A predecessor to PACE, the Ellen MacArthur Foundation's CE100 Network is a community of companies, policymakers, and scholars working on CE and is currently marketed as "the world's leading circular economy network" (Zarin, 2019).

Institutionalization
This section closes by considering the institutionalization of CE.Fields vary in their degree of institutionalization and are typically less institutionalized than disciplines (Holbrook, 2013;Krishnan, 2009;Tight, 2020;Trowler, 2014).Ehrenfeld (2004, p. 828) proposes four characteristics of institutional structures: "(i) a system of beliefs about how the world works, (ii) strategies and norms governing what one should do when addressing a particular domain of action, (iii) a common set of tools and technologies to be used toward meeting one's objectives in that domain, and (iv) a set of legitimating authorities." Activity on all of these fronts suggests that the CE field is becoming more institutionalized.Along with the growth in scholarship, the concept of CE has gained traction among governments in the past decade, with institutionalization most evident in China and the EU (both in constituent countries and in the EU governance system overall).For example, the Circular Economy Action Plan is one of the main building blocks of the European Green Deal of the European Commission (EC, 2022b), and the Dutch government has committed to establishing a fully circular economy by 2050 (Reike et al., 2022).
Beyond these efforts, there remains little debate about what CE transition entails, and tools and technologies aiding the achievement of CE policy goals continue to be developed.Importantly, institutionalization tends to be a self-perpetuating process-additional drivers (e.g., journals and faculty chairs) require and encourage the pursuit of more specific CE initiatives to justify resource commitments; in turn, the resulting deeper

CONCLUSION
When a field is recognized by scholars and institutionalized through academic authority structures, knowledge development is further enabled.
If a sociologist begins studying CE while failing to consider the topic as a research field, the scholar may be concerned only with addressing research gaps in sociology.However, when considering CE as a field, that scholar's perspective can become more integrated, interdisciplinary, and multi-methodological. From the resulting engagement emerge jointly conceived research agendas and progress toward more holistic theorizing.
Moreover, status as a field also commands certain prestige in the academy.While practitioners may not be concerned where advice originates (provided that it works), "it would remain relatively easier for others in the academy [. . .] to ignore the findings" (Tight, 2020;p. 416) if the topic is not recognized as a field.Such recognition can broaden the visibility of research to scholars in allied fields and attract new researchers and resources.
Recognition and institutionalization of a field also imply a certain epistemic stability.While authorities give in-principal and rhetorical support to interdisciplinarity and conceptual novelty, commitment to disciplinary silos remains embedded in how organizations (e.g., universities) are structured and how the research community (e.g., an editorial board) evaluates work.As such, researching a topic like CE can be considered a risky career choice in comparison to researching traditional disciplines (Ledford, 2015;Okamura, 2019;Rhoten & Parker, 2004); it can be mistakenly perceived as unfocused or arbitrary.Broad consideration of CE as a field would ensure a more solid base for emerging thinkers to position their work.
There remain other challenges to CE's progress as a field.Much CE research continues to be carried out in Whitley's (2000) academy-focused "Mode 1" knowledge production system.While some of the most influential CE research has been authored by practitioners and practiceoriented researchers, the field has become more academic and new scholarly ideas may not always support practical implementation.For example, recent research has focused on the relationship between CE and economic growth, including degrowth (Hobson, 2020;Hobson & Lynch, 2016;Kirchherr, 2021b).Some practitioners with whom we spoke for this article expressed concern that this trend may lead the field to become increasingly dogmatic; arguably, few businesses would embrace academically "critical" discourses (Henry et al., 2020(Henry et al., , 2022)).
Furthermore, the challenges of practical implementation (van Keulen & Kirchherr, 2021;Vecchio et al., 2022) may compromise the ability of the CE concept to deliver on its promise of fostering sustainability.CE may thus become too complex or contradictory for at-scale implementation (Korhonen et al., 2018(Korhonen et al., , 2018)), while the "circular economy paradox"-that is, ample effort but little progress-may turn practitioners and eventually academics away from the field.CE would then suffer the fate of topics like cradle-to-cradle (Braungart & McDonough, 2009) and biomimicry (Mathews, 2011), which once drew attention and resources but ultimately became niches superseded by the next sustainability buzzword (Henry et al., 2021).
CE may be the most celebrated sustainability idea of the past decade, and its salience is likely to endure in the coming decade.Ten years after publication of the Ellen MacArthur Foundation's flagship report (EMF, 2013), CE draws attention across academic disciplines and practitioner communities.We propose that CE has indeed emerged as a field of scholarship with an increasingly coherent set of shared beliefs and concepts, numerous practical resources, enabling authorities, and a vibrant community of actors.The field connects scholars and practitioners to an extent that is unique among sustainability-related research subfields.Further, the institutionalization of CE is well-advanced in academia and progressing in industry and government, suggesting that the concept is a robust and durable field of both scholarship and practice.
name suggests its original emphasis.The journal Frontiers in Sustainability created a dedicated CE subsection, while Springer recently launched the journal Circular Economy and Sustainability.A group of scholars has also recently launched the Journal of Circular Economy, an open access outlet that is outside the mainstream academic publishing realm.The growing volume of CE research will likely strengthen the demand for CE-specific special issues, subsections, and dedicated journals.Authority also manifests itself in CE-specific research units within universities (e.g., the Circular Economy Centre at the University of Cambridge) and chair positions focused on CE-related research.For example, the Technical University of Berlin (TU Berlin) maintains a Chair of Circular Economy and Recycling Technology, the University of Freiburg a Chair of Societal Transition and Circular Economy, and the Polytechnic University of Milan a Chair of Circular Economy Business Models.The University of Turku in Finland is creating a CE chair with endowment funding in excess of 600,000 EUR.These chaired faculty positions are often supported by funding for additional research staff, enabling the development of focused research groups.While no "Department of Circular Economy" within a university has yet been publicly launched, these chairs reflect relatively permanent commitments that indicate CE is becoming institutionalized as a field.

TA B L E 1
Conceptualizing circular economy as a field of scholarship.
Recent guides and handbooks on circular economy.
TA B L E 2