The state and ‘field’ of comparative higher education

ABSTRACT Comparative higher education is arguably lagging behind its sister field of comparative education. It has been developed more recently, lacks in institutional structure, its intellectual debate is marginal, and its political construction is incomplete. Yet, despite the pitfalls of comparative higher education research, this article argues that higher education would benefit highly from a strong and united field of comparative studies, built around a community of comparatists. A strong comparative research field in higher education would serve incredibly well in a sector that is highly internationalised, helping develop theories and conceptualisations, as well as methodologies. It would help strengthen research and further our understanding of higher education at all levels – global, international, and local.


Introduction
For as long as science has existed, so have comparative studies. The need to compare entities to find similarities and differences and decide on best practices has always motivated science, and particularly social sciences. However, comparative studies have become more prevalent in the past 200 years, and their importance has increased significantly since World War II. Comparative studies have thus become established branches of many academic disciplines, such as politics, philosophy, and social sciences. Recently, the number of comparative studies have further increased because of changes in the structure of research and the rising importance of external funders, including supranational organisations that value transnational collaborations and encourage comparative projects.
As a sub-discipline or sub-field, the focus of comparative studies has been on methodology, with the definition and development of the 'comparative method'. Comparative studies, through the comparative method, should ultimately lead to the exposition of causality -one mechanism triggering another -or generalisability -applicability of the research findings to the whole population. The methodological focus has been reflected in early definitions, superseding the emphasis on content. For instance, Lijphart (1971) stated that comparative politics 'indicates the how but does not specify the what of the analysis' (p. 682). Another example comes from social policy, where Higgins affirmed that 'comparative analysis is a methodology, rather than a substantive area of study' (as cited in Kennett, 2004, p. 94).
As part of this Special Issue on the 'international', 'comparative' and 'global' in research on higher education, this paper focuses on the development of comparative higher education as an academic field. It finds that, while higher education is a highly globalised sector, its comparative research lacks both maturity and a recognisable identity, especially when compared to comparative education. The conversation about what it means to do international and global research in higher education is, however, a perfect opportunity to remind researchers of the promises of comparative research. Continued efforts to develop comparative studies in higher education are essential to contribute to thoughtful and rigorous research at all levels -local, national, and global. A mature field of comparative higher education could therefore help shape and strengthen future higher education research.

Comparative education
It is impossible to discuss comparative higher education without relating it to comparative education. Throughout the years, the field of education has been successful in undertaking, theorising, and organising comparative studies. Comparative education can be traced back to 1817 and the publication of Esquisse et vues préliminaires d'un ouvrage sur l'éducation comparée, et séries de questions sur l'éducation by Marc Antoine Jullien. Although Jullien can be contested as the founding father of comparative education (Epstein, 2017), his canonical book stands out in its ambition to provide the groundwork for a comparison of all European school systems -including the analytical instrument to do so. This early work of comparative education had therefore already a strong methodological perspective.
It would be beyond the scope of this article to write a detailed history of comparative education. However, it is important to note that, at its beginning, comparative education was 'an ideological project for action on the world' (Cowen & Kazamias, 2009, p. 5). Comparative education could not be dissociated from a political context that sought to build massified national systems of education and looked to foreign systems for reforms. The visibility of comparative education intensified after World War II, when reconstruction and the Cold War put education at the forefront of Western national agendas in an effort to foster economic development and social mobility (Carnoy, 2019). At the same time, international agencies concerned with education proliferated and comparative education was institutionalised in universities and research centres (Turner, 2010). Consequently, three strands of teaching and research appeared and are sustained to this day (Carnoy, 2019). First, social science methods were introduced into the study of comparative education, departing from what were mostly descriptive studies. Second, driven by not only the US but also international agencies (e.g. UNESCO, World Bank), international education development arose, applying comparative education research to 'educational and development activism' (Carnoy, 2019, para. 9), i.e. to advance democracy and economic development in developing countries. Finally, academics' efforts to gather a vast amount of data to compare student outcomes across countries led to the advent of international testing as we know it today. In academic research, this led to an increase in cross-country comparative approaches using increasingly complex statistical analysis (Hanushek & Woessmann, 2011), diverging from comparative education's historical reliance on qualitative and historical studies. 1 It is particularly interesting to contrast contemporary comparative education with comparative higher education. Despite a crisis and ensuing debates in the 1960s-70s focused on the question 'What is comparative education?' a definition is still eluding most comparatists. Of the method discussion that happened in the 1960s-1970s, Little (2010) argues that little remains today. Similarly, the purpose of comparative education, the questions it is meant to answer, and the units it should deal with are the focus of ongoing debates. Little (2010) therefore proposes to unite comparatists around a common aim rather than an elusive and ever-changing definition of the field.
Arnove (2010), a key comparatist for the past five decades, defines the field around three dimensions: scientific, practical/ameliorative, and global. The scientific dimension consists of theory building 'with comparison being absolutely essential to understanding what relationships pertain under what conditions among education systemsociety variables' (p. 828). The practical/ameliorative dimension ensures that comparative education contributes to enlightened evidence-based policy-making. Finally, the global dimension is concerned with leading to international understanding and peace.
Recently, postcolonial critiques have extended these ongoing debates, casting a new light on the histories, purposes, and epistemologies of comparative education. Calls have been made to recognise the 'colonial entanglements' (Takayama et al., 2017, p. S11) that characterised the establishment and development of comparative education -from educational ideals of imperialistic countries being forced on colonial dependencies at the beginning of the 20 th century to replicating Western educational policies in developing countries for the sake of modernity during the Cold War. Recognising that comparative education knowledge has been developed based on uneven power dynamics is nowadays essential to redefine comparative education outside of the dominance of Western epistemologies (Takayama et al., 2017).
It would be easy to consider these ongoing debates over what is comparative education the failure of an academic field to unite. However, they might be at the very core of what makes comparative education an academic field. Manzon (2018) argues that comparative education is a constructed field, based on both intellectual and institutional structures. The ongoing debate over the object, method, and purpose of comparative education (Manzon, 2011) is part of its intellectual construction and relates to Arnove's scientific dimension. It allows the field of comparative education to change as it adapts to the world and interacts with other academic fields. As far as comparative education is concerned, the capacity to redefine itself has been important in recent years as it crossed paths with postcolonialism (Takayama et al., 2017) and development studies (Little, 2000). In particular, development studies have revealed a new path for comparative education to contribute to global development goals, including the analysis of positive and deleterious effects of globalisation and developing a more comprehensive view of educationbeyond economic development models and cultural changes objectives (Arnove, 2010). The intellectual construction of the field also provides agency to the comparatist, who can shape and define the field according to their own context. As Marginson and Mollis (2001) argue, there is a positionality to the definition of comparative education: 'it includes many diverse perspectives determined by financial interest or geopolitical location, by social or cultural agendas, or by intellectual preferences ' (p. 583).
An appropriate institutional structure is essential to an academic field, giving physical space to the intellectual debate. It also supports research, disseminates ideas, and unites comparatists into an academic community. The research community in comparative education takes part in many societies worldwide. The World Council of Comparative Education Societies regroups 43 member societies (World Council of Comparative Education Societies, n.d.), showing the prevalence of comparative education in the global academic space. These societies organise regular events, including annual conferences, that represent as many occasions for researchers to debate comparative education and enrich the field with new theories, ideas and projects. Comparative education research is also supported by dedicated academic journals. Four core journals were first published between 1957 and 1975: Compare, Comparative Education, Comparative Education Review, and Prospects. Other journals have since been created in many languages. The establishment of a new journal in 2017 under the umbrella of the World Council of Comparative Education Societies, Global Comparative Education, suggests that academic research on comparative education is increasing and there is space for more publications to disseminate its outcomes.
However, the institutional structure supporting an academic field cannot be limited to research. Teaching is essential to train new comparatists with the history, methodologies, conceptual frameworks and theories that constitute the field. It ensures that new comparatists have a common background that enables them to understand, develop and further comparative education. A teaching institutional structure can be demonstrated through the existence of dedicated courses and textbooks. As far as comparative education is concerned, Manzon (2018) counted two Bachelor and 14 Master degrees in 50 countries, as well as a plethora of courses. Textbooks have also existed since 1918 along with the publication of Comparative Education: Studies of the Educational Systems of Six Modern Nations by Sandiford. An increase in textbooks in local languages happened after World War II, mirroring the expansion of the field (Manzon, 2018), a trend that has continued to the present day. For instance, the second edition of Marhsall's Introduction to Comparative and International Education was published as recently as 2019, while the sixth edition of Soshi's Textbook of Comparative Education was published in 2018. Those recent publications of revised editions reveal an active ever-changing academic field.
To Manzon's intellectual and institutional constructions, I would add that comparative education is also the fruit of a political construction, in line with Arnove's practical/ ameliorative dimension. Social sciences, including (comparative) education, have important and multi-faceted bearings on policy-making (Jennings & Callahan, 1983). As such, they need to sustain a relationship to policy-making and policy-makers to provide meaningful and current research. Comparative education has undeniably been historically strengthened by nations' need to build competitive educational systems in the knowledge economy, to ensure their labour force and human capital reserve is competitive globally (Organisation for Economic Co-operation and Development, 2011). As a result, international policy benchmark instruments have flourished, including PISA and TIMSS, collecting data and providing instruments for direct comparison of systems' outcomes (Morris, 2015). These instruments provide a benchmark for comparative education and allow us to look for best practices elsewhere -as evidenced mostly by high test-scores, but also student happiness or equity. Although these quantitative data provide raw numbers, ignoring issues and problems of comparison like contextualisation, these tests have become both an instrument to evaluate policies and a rationale for reforms (Niemann et al., 2017), making knowledge gained through comparative education essential to policy-making. The importance of policy in the construction of comparative education as an academic field is also seen in the prevalence of policy borrowing and lending as a research area, that highlights how policies travel internationally, the context in which they work, and how they adapt (Steiner-Khamsi, 2016). The importance of policy was already underlying the work of Jullien (1817) and has become stronger in recent years, establishing comparative education as a needed academic field from a policy standpoint and reinforcing its importance in the realm of scientific knowledge.

Comparative higher education
The section above establishes comparative education as a strong academic field based on its long history, intellectual construction, institutional structure, and strong relationship with policy. This section provides an account of comparative higher education in the same regard to evaluate its status and development as an academic field.

History
Comparative higher education is a relatively new 'field' of investigation, that mostly started in the 1980s. Throughout its 40-year history, several definitions have emerged. For instance, Teichler (1996) defined comparative higher education as 'research addressing phenomena of higher education in more than one "culture", "society" or "nation" systematically or in a single one in a comparative perspective' (p. 448). More recently, Kosmützky (2015) stated: '[comparative higher education] analyses and compares similarities and differences as well as convergences and divergences' (p. 355). The first definition emphasises the international component, while the second includes the most elementary description of comparative studies -the search for 'similarities and differences'. Both definitions resemble tautologies, using derivatives of 'compare' to define comparative higher education. Although these definitions are valuable to start a discussion, they lack specificity in dealing with higher education. In doing so, they mirror the need for more indepth critical debates about the role, purposes, and methodological issues of comparative research in the specific context of higher education.

Institutional structure
When questioning the realisation of comparative higher education as an academic field, in comparison to comparative education, one striking element is the lack of institutional structure. There is only one journal that specifically caters to comparative studies in higher education: the Journal of Comparative and International Higher Education started in 2009. Studies about comparative higher education are otherwise published in journals with wider scopes, including higher education or comparative education. Similarly, there are no societies dedicated to comparative higher education, with again reliance on the field of comparative education or to a lesser extent international development for conferences and community-building. For instance, the Comparative and International Education Society (CIES) includes a Higher Education Special Interest Group. This overall lack of dedicated research structure is mirrored in research centres, with no research centre globally specifically dedicated to 'comparative' higher education as would be evidenced in their name . The teaching structure is similarly deficient, with no official textbooks, no degrees, and few courses around the world.
Evidently, comparative higher education lacks 'the standard accouterments of any academic field' (Altbach, 2014, p. 14). As a result, higher education comparatists face a disjointed field, making it difficult to build a community and an identity.

Intellectual debate
In part because of the lack of dedicated dissemination outlets, the intellectual debate about comparative higher education -its identity, its object, its methods . . . -has remained marginal. A research review of all panel sessions of the Higher Education Special Group at CIES between 2014-18 failed to find any trend relating to the conceptualisation of comparative higher education, instead highlighting trends around objects of study (Madden & Blanco, 2019). Much of the recent debate has been published in just two journals as a result of three special issues and a special section: 'The state of comparative research in higher education' published in Higher Education in 1996; 'Special section: perspectives on comparative higher education' in Higher Education in 2001; 'Challenges and trends in comparative higher education' in Higher Education in 2014; and 'Towards a methodology discourse in comparative higher education' in Higher Education Quarterly in 2020. Over the past 25 years, this adds up to only 28 articles published in dedicated channels that aimed to develop and advance the debate about comparative higher education. The small number of outputs, as well as interested researchers, in addition to the lack of structure to create an academic community, might prevent the small area of study that is comparative higher education (Kosmützky & Krücken, 2014) from fully developing into an academic field.
Although limited, the debate about comparative research in higher education has brought important conceptual frameworks and theorisations. Recent debates have mostly covered three topics: contextualisation, methods, and comparative research projects -all of which have received some attention in comparative studies in other fields. Contextualisation and the recognition of the uniqueness of higher education systems are extremely important in comparative research to avoid misguided generalisation . Välimaa (2008), for instance, called for paying particular attention to differences in social dynamics between two systems of higher education. He claims that, in undertaking comparative higher education projects, researchers should reflect upon differences between systems in terms of time, space, history, geography, power structure, language, objectives etc. Similarly, in their attempt to help contextualised international comparisons, Välimaa and Nokkala (2014) warn against the use of linguistic equivalents (similar word) rather than effective equivalents (similar function), to avoid mistranslation of cultural objects and their inadequate comparison. One example from the field of higher education research is the lack of equivalency between 'colleges' in the world.
The methodological discussion on comparative higher education research follows many similar debates regarding comparative studies in different academic fields, including in comparative education (Kosmützky, 2016). Recent contributions have addressed the type of research studies and their objectives, and, like in other fields, contrasting views have been heard relating to causality being the finality of comparative studies (Hauptman Komotar, 2021). On the one hand, some researchers argue that the aim of comparative studies in higher education should be to provide causal explanations (Goedegebuure & Van Vught, 1996). On the other hand, Bleiklie (2014) proposes a typology of approaches to higher education comparative studies, of which only one is linked to causality. In doing so, he acknowledges valuable contributions of comparative higher education research beyond causality. Specifically, he recognises five types of comparative research in higher education: 1) single country studies that create knowledge based on a country's singularity, 2) juxtaposition when several case studies are undertaken in parallel highlighting the salient features of each case, 3) thematic comparison defined by a common set of questions looking at similarities and differences in a small number of units, 4) the identification of causal regularities when the same phenomenon leads to the same consequences in different contexts, and 5) grand theories that attempt to explain a global phenomenon. More recently, Cantwell (2020) discussed the fallacy of causal research in comparative higher education research, but provided realist alternatives to enhance its explanatory power. He argues that by 'formalising thinking about method just a bit, comparative and international higher education research can sharpen claims of explanatory power via several research approaches' (p. 154). He provides four approaches to help enhance the explanatory power of comparative higher education: 1) bounded cases, where case-specific causality can inform theorisation, 2) specified phenomena, where a question is explored using a plurality of methods thus leading to a comprehensive understanding and explanation of the phenomenon, 3) mechanism-based approaches, where research identifies plausible pathways that lead to a real phenomenon, and 4) tracing macro-social trends, where research tries to explain the link between higher education and social change.
Research on comparative higher education has also often addressed the topic of comparative research projects and their management, brought forth by authors' own experiences (Hope, 2015;Kosmützky, 2018;Teichler, 2014). The difficulty of working in cross-country research teams is highlighted. Issues of decentralised funding, lack of agreement between country researchers, lack of methodological and data coordination can all potentially compromise the research project, its results and their comparability, and generalisability. A side effect of these common issues in comparative research projects is longer than expected time to completion, in turn creating potential funding and human resources strains. An important additional drawback to comparative higher education research projects is the choice of countries, which is most likely the result of researchers' personal networks and language competencies (Teichler, 2014). This constitutes a convenience sampling strategy, limiting greatly generalisability. These commonly described drawbacks to comparative research projects in higher education raise important issues regarding the quality and validity of these studies, and merit wider consideration in the debate on comparative higher education.
While this article does not claim to give an exhaustive summary of available research, the examples provided above show that there is indeed a debate on what it means to undertake comparative research in higher education, and the specificities linked with such research. However, as noted above, this remains a marginal debate, where 'methodological issues are [. . .] not being discussed actively and consistently and there is no codified knowledge base' (Kosmützky, 2020, p. 222), making it hard for researchers undertaking comparative projects to identify a common existing conceptual and methodological basis. As a result, applied comparative research in higher education lacks rigour. Kosmützky (2016) analysed international comparative research in six journals -focused on higher education or comparative education -from 2004 onwards. Only 35% of all comparative articles had explicit explanations of the choice of countries included in the samples, 34% had implicit justifications including availability of data or funding. The rest did not include any justification. This perfectly shows the shortfalls of comparative higher education research. In a research area devoid of constructive and constructed debate about the research itself, applied researchi.e. comparative research projects -often falls short methodologically. The example of the choice of countries is particularly evocative since sampling in comparative research was theorised in comparative politics in the 1800s (Mill, 1843(Mill, /2011 and has been applied to many different comparative studies since. This, therefore, raises the question of the visibility of the intellectual debate on comparative higher education research.

Political construction
As mentioned before, the construction of comparative education as an academic field greatly benefited from a political push, with nations eager to know how well their system fares compared to others. While higher education has taken significant importance on the international stage politically, it has always trailed behind education. This has been shown in particular by the World Bank's long-lasting disregard for higher education (Collins & Rhoads, 2008) as well as the absence of higher education in global initiatives such as the Millennium Development Goals (McCowan, 2019). In addition, instruments to compare higher education systems on a global scale are lacking. An attempt by the OECD to reproduce the success of PISA at the tertiary level, through the Assessment of Learning Outcomes in Higher Education (AHELO) project, started in 2010. It aimed to provide governments with an assessment of the quality of their higher education system and an international benchmarking tool for teaching and learning. However, ten years on, AHELO had still not managed any substantial advances, with the pilot project considered a failure by many and being discontinued in 2012 (Altbach, 2015). AHELO was revived in 2015 for a main project, which raised many concerns, including: its cost, the comparison of systems with different curricula, the differences between disciplines, and system stratification, to name only a few (Altbach, 2015). One of the main issues behind the failure of AHELO is the difficulty to compare achievements transnationally in higher education, in part because of the global variability in systems. It has to some extent prevented the replication of statistical analysis that link system characteristics to educational outcomes as in comparative education. Tools to compare higher education systems remain therefore limited to datasets gathered by global organisations -including the OECD, the World Bank, UNESCO and the European Union -that collect high-level quantitative indicators. One noteworthy exception is the Eurostudent dataset, which was funded by several European governments and provides comparative data for Europe at the student-level. Highlevel datasets have, nevertheless, become a key tool for policy-makers, exerting power and influence on systems worldwide (Mills, 2022).
The most popular globally available comparative tools for higher education today are institutional rankings. While widely recognised as flawed, they have been shaping higher education for nearly two decades (Hazelkorn, 2015). But most rankings operate at the institutional-level, thus failing to consider whole systems -except for the U21 ranking. They thus pushed many countries -including France, Russia and China -to channel large investments into a small number of high-achieving institutions, sometimes at the expense of the rest of the system (Yudkevich et al., 2015). In doing so, the stratification of systems is intensified, with rankings misrepresenting systems through a couple leading institutions.
While interest in looking at other systems has increased in recent years in both research and policy, as have supra-national actors (Teichler, 2014), the political construction of comparative higher education research is still in development. Comparative instruments have failed or have been damaging to systems as a whole for the benefit of select institutions. Comparative higher education, as a result, still has a significant way to go to become an essential and positive instrument for policy-making and policy reforms, which will then be mirrored in gaining importance as an academic field.
There are therefore important shortcomings in the development of comparative higher education that need to be overcome to establish comparative studies as a research (sub-)field. Because of these shortcomings, it can be argued that comparative research projects may suffer from a lack of intentionality of academics in undertaking comparative higher education research. Researchers multiplying countries in their research or writing case studies of other systems might not be fully conscious that their research falls under the umbrella of comparative studies, and of the associated theories, methods and literature, especially when considering that higher education research is by nature very internationalised. Unintentional comparative studies are problematic because they can potentially lead to lower quality research due to approximative methodologies, unfamiliarity with useful theories and frameworks, and lack of recognition of researchers' positionality. This last point is particularly important in a field that is very stratified and globally unequal, to properly acknowledge where researchers situate themselves and ensure inclusivity of comparative studies. A more prominent discussion on comparative higher education -furthering the intellectual debate, developing an institutional space, and fostering a political construction -would generate better awareness of the specificities of comparative higher education research and of methodologies, frameworks, and theories to shape research designs and make studies more rigorous. The section below explores in more detail why we should, as higher education researchers, care to work towards a more developed comparative research field.

The pitfalls of comparative studies in (higher) education
The adoption of the comparative method in higher education is not without issues. Although the pitfalls described below are mostly shared with comparative studies in general and comparative education in particular, a particular emphasis is given on how they particularly impact comparative higher education research. First and foremost, comparative studies are associated with the nation-state as a unit of analysis. Higher education research, however, is experiencing a retreat of the nation-state. In particular, the globalisation movement and internationalisation of higher education argue that higher education is influenced by global phenomena that are not bound by country borders, supporting the denationalisation of higher education (Cantwell, 2016). This rationalisation is fuelled by the fact that higher education's actors and outcomes ignore borders: academics and students are mobile on global markets, while knowledge knows no physical border. In addition, because it is associated with countries as a unit of analysis, comparative higher education is tied to the criticised concept of methodological nationalism, which refers to 'the taken-forgranted assumption that nation states and their boundaries are the "natural" containers of societies and hence the appropriate unit of analysis for social sciences' (Dale, 2005, p. 124). Methodological nationalism is even embedded in concepts of international, transnational and supranational research -that all presuppose and are reliant on the existence and legitimacy of nations (Dale, 2005). Shahjahan and Kezar (2013) highlight two reasons why methodological nationalism may corrupt higher education research. Methodological nationalism assumes that national processes are bounded by nation-states, thus ignoring both the porosity of national borders when it comes to higher education as well as global forces that influence higher education national systems and stakeholders. Moreover, methodological nationalism in higher education research strengthens power inequality between groups within and outside of the country. It disregards the issues of minoritized groups because of the economic and political competitions between nations, while ignoring the interests of groups beyond national borders in designing higher education policies. Overall, the nation-state concept fails to capture the essence of higher education, its global character, and its porousness beyond physical borders. Comparative higher education that is limited to nation-states as a unit of analysis therefore is bound to misrepresent higher education and its ties to important cross-border forces and influences.
Second, the question of comparability is pervasive. National higher education systems are influenced by historical, political, demographic, and cultural contexts that have no exact equals in other countries. This is particularly visible in the extreme differences in curricula between different countries, stemming not only from the important autonomy of teachers but also from interactions with national labour markets, the economy, and politics (Barrier et al., 2019). Strictly speaking, higher education systems are therefore uncomparable, creating an important caveat in the mere thought of comparative research. This is not unique to higher education and the distinctive characteristics of nation-states could indeed make some comparative effort moot.
In addition, it is complicated for researchers to claim expertise in more than a few countries, as studying a country without having experienced it might limit the knowledge one can gather. Lack of information; lack of cultural, political and systemic awareness; potential value judgement based on the researcher's own experience might all undermine findings from comparative studies (Teichler, 2014). This is a particularly important caveat in higher education comparative research, as researchers all experience their object of study from within -academics studying academia. An associated risk comes from the widespread use of approximative methodologies, including a convenient sample of countries of study that limit generalisation and creates inequalities in regions/countries as object of study. Another example would be the limit imposed by the language proficiency of the researcher, that might a priori eliminate a significant number of countries and/or regions from being potential objects of study (Teichler, 2014). Of the lack of multilingualism in comparative education, Manzon (2018) states it 'limits [researchers'] intellectual horizon and discourses. It insulates communities of scholars and draws invisible boundaries to scholarship' (p. 5). Together, these issues mean that, often, comparative higher education studies fall short of the ideals of generalisability or causality that underscore comparative studies in general.

Why higher education research needs comparative studies
Despite these caveats and risks, there is a significant space and need for comparative higher education study that can contribute to an enrichment of higher education research generally.
First, despite the criticisms of country-level comparative research, countries provide a clearly defined unit of analysis which does build on some unity historically, culturally, and politically. A corollary of this argument is that data are often found at the country level. This is true not only of statistical data for quantitative analysis, as exemplified by comparative datasets such as Eurostat or 'Education at a Glance', but also of data for qualitative research, such as documents or policy discourses. Most importantly, higher education systems are mostly defined at the national level, with policies and regulations decided upon and implemented at the state (for federal countries) or national levels. Comparative studies using countries as units of analysis therefore provide unique opportunities to evaluate policies voted and implemented at the national level. Parkyn (1977) indeed stated that one of the goals of comparative education research is 'taking into account factors that cannot adequately be observed and understood within the limits of any particular society' (p. 89). Finally, comparative studies using nation-states as a unit of analysis can constitute an effective means of testing whether the impact of the nation-state has actually declined and thus provide an opportunity to respond to some of the critiques of methodological nationalism.
Second, comparative studies do not need to be constrained to using nation-states as units of analysis. They are flexible in the unit of analysis, providing a unique potential to reconcile the different ways researchers think about higher education internationally and to deal with closely interwoven local, national and global levels (Marginson & Rhoades, 2002). It also allows research on knowledge and science which are not bound by national borders. Therefore, comparative higher education could provide frameworks and methodological tools to address concepts that go beyond the nation-states or that are contained within it, e.g. flows when analysing mobility (Cantwell, 2020) or global cities when evaluating higher education inequity (Marginson, 2018). This connects with Marginson and Rhoades' (2002) glonacal agency heuristic, which was designed with comparative higher education research in mind. It provides a framework for comparative studies to not only limit itself to the national level, but also account for local and global levels, as well as sub-and supra-level research.
Third, it is impossible to deny that higher education institutions evolve in an international space. It can even be argued that universities are the only institutions that have always been global (Altbach, 1998). Internationalisation especially has become an inevitable dimension of higher education over the past 30 years, in research and in practice. Academic mobility, internationalisation of the curriculum, and transnational research collaboration are but a few of its manifestations in higher education today (De Wit et al., 2015). Although internationalisation contributes to making higher education more global than ever, little is known about the intersection of internationalisation and comparative higher education. This is problematic in that the attention given to internationalisation potentially directs resources away from comparative higher education. Exploring this intersection could therefore be essential to the development of comparative higher education, taking advantage of the unwavering attention given to internationalisation to further the development of a comparative field.
The international nature of higher education has repercussions at the system level too. Policy borrowing has been a reality in higher education -as for primary and secondary education -for a long time, looking for evidence abroad of 'best practices' (Teichler, 2014, p. 397) while being aware of trade-offs (Delisle & Usher, 2019). Unfortunately, policy borrowing without regard for the lending or borrowing contexts can be damaging to the borrower, especially in regions with less power on the higher education global stage (e.g. Lee & Naidoo, 2020). It is, therefore, the duty of the higher education researchers to also look abroad, through comparative studies, to precede policy-makers and be able to influence policy through scientific evidence, and aid in the adaptation of foreign policies to the national and cultural context. These types of study will give a new intentionality to comparative studies in higher education, being steered by policy impact, and provide comparative higher education with a currently elusive political construction.
Finally, developing comparative studies in higher education is an opportunity to improve higher education research generally. Through comparative studies, we can learn more about various higher education phenomena, by evaluating the ways they work in different contexts and environments. It can help deconstruct assumptions based on analysis in select locations only (Teichler, 2014) and foster a global and inclusive understanding of higher education. At a time when comparative education is criticised for its colonial and neo-colonial roots and epistemologies (Takayama et al., 2017) and as the postcolonial agenda arises in higher education, comparative higher education studies could be fundamental. The development of an inclusive field of comparative higher education that takes into account postcolonial critiques could be a unique opportunity to give attention and importance to the invisible and silent voices in current higher education studies. These comparisons and associated reflections on 'elsewhere' will also bring forward the chance to learn more about the researchers' own systems through a relative lens. They help challenge both comparative chauvinism -researchers viewing their higher education system as the best -and comparative humility -researchers being over-critical of their own system (Teichler, 2014). Comparative studies can therefore deepen our conceptual understanding of higher education as an object of research, helping develop inclusive theorisation for higher education research.
This last argument is supported by previous advances in higher education research that were achieved through international comparative perspectives. Comparative higher education research has provided instruments and categorisations that help define models of higher education systems, recognising the importance of cultural and/or socio-political traditions; created new theories based on 'similarities and differences'; and increased our understanding of university systems, higher education phenomena in different contexts, and global phenomena. An important example is Clark's (1983) triangle of coordination which defined systems based on how governance is shared between state authority, market and academic oligarchy. Clark's triangle has seen many adaptations over the years and remains the basis of ground-breaking work in comparative higher education. Other models that have helped define the way we research higher education systems include Altbach's (1981) concept of centres and peripheries and Trow's (1973) typology of access level in higher education, both developed comparatively and still very much used today. In parallel, however, there is a recognition of the difficulty in defining global models of higher education systems, in part because of the differences in what is encompassed in the 'system', which leads to a 'bewildering variety of concepts, terms, and descriptors' (Teichler, 2020, p. 773).
There are therefore many reasons to keep developing comparative higher education research further and turn it into a proper academic (sub-)field. Theoretical and methodological conversations, in dedicated institutional spaces, would prevent comparatists from falling into the pitfalls highlighted in this article, while building a robust research field directly benefitting higher education research. It is important to note that the development of comparative higher education research cannot be done by divorcing it completely from mainstream higher education research. Such division would harm both streams of research and prevent them from advancing and progressing together. Comparative higher education research must find a space to be recognised and to develop an identity, while keeping strong ties to the research and debates in higher education.

Reflections for the future
Developed in this article is the idea that comparative higher education is not yet established as a distinct (sub-)field within higher education research, leading to nonrigorous research and potentially bypassing many benefits for higher education research as a whole. It is, therefore, important that higher education comparatists take steps to discuss the objectives of comparative higher education, develop its identity, and create a scholarly community. The development and quality of comparative higher education will depend on this community, providing conceptualisation, theories and methods for researchers undertaking comparative projects.
In this regard, comparative higher education has the chance to be able to build upon many historical academic traditions in comparative research, in particular in the social sciences and humanities (Kosmützky, 2016). The comparative method has been developed for other objects of study and could be applied to and adapted for higher education, the progress made elsewhere ensuring robustness. In particular, the comparative method provides tools to help create concepts and classifications, test (causal) hypotheses, and sample cases. These tools could be adapted to higher education comparative research, providing a first step towards more rigorous and unified comparative studies. In addition, comparative higher education can rely on decades of research and conceptualisation in comparative education, providing instruments, concepts and frameworks that can be adapted for higher education, since they stem from similar concerns and issues.
In addition to gaining inspiration from comparative research in other fields, higher education comparatists need to create an identity which leads it to be considered an academic (sub-)field. This cannot happen without, first, reflecting on who undertakes higher education research. Not only will it foster a community of scholars sharing similar research interests and methodologies, but it will help define who higher education comparatists are. This community can reflect on the past, present and future of comparative higher education, including what research is being undertaken under the umbrella of comparative higher education and what research should be done under this umbrella. Scholars can then shape a mission and objectives for researchers undertaking comparative projects. In addition, the debate should help enlighten what it means to do comparative studies in higher education, in terms of providing tools and steps for rigorous research. Finally, there is a need to define where this debate and research is taking place academically, for instance, where this research is published or presented. When it comes to publication, it is important for editors and peerreviewers to be aware of the debates and methodologies surrounding comparative higher education research as they are the safeguard for rigorous research. All these steps are designed to give greater awareness of comparative higher education as a branch of higher education research and increase mindfulness as to the specificities of comparative research, building it into an academic field.
Lastly, it is essential to build up comparative higher education as an academic field to ensure intentionality and honesty in comparative research. When designing comparative projects, higher education researchers should ask whether what they are doing is 'comparative' research, why they are undertaking comparative research and what values it brings to answering their research question, what frame of reference they personally bring to the research, why and how they choose the units of comparison, what units are missing from their research, and how their research inscribes itself in the field of comparative studies. By answering these questions, researchers will become more intentional in their use of comparative research and more honest about their own bias and the bias of their research, developing comparative positionality. From a postcolonial perspective, it is essential to recognise researchers' own power, both in the data they choose to use, and in their own positions within the field and how these define how they see the field. Takayama et al. (2017) stated about comparative education: 'Structural inequalities between the researcher and the researched, and between the home country of the researchers and the targeted countries, are constitutive for the very difference that [. . .] researchers are to uncover' (p.S3). Intentionality and positionality will provide important information as to the limitation of comparative research, most notably when it comes to generalisability, a key outcome of comparative research.
In a Special Issue dedicated to defining what it means to conduct 'international' or 'global' research in the highly globalised research field of higher education, reflecting on what it entails to do comparative research is essential. While comparative studies might very well be a distinctive field of studies, differing from 'international' or 'global' studies, their development could inform and strengthen all areas of higher education research, independently of the academic discipline of reference. This article brings the issue of the under-development of comparative higher education research to the foreground, hoping that the recognition of its state and of the importance of this type of research lead to further debate and improved awareness in the academic community.