Introduction

1The health of coastal marine ecosystems continues to decline at an unprecedented rate, despite numerous interventions by scientists, governmental and non-governmental organisations and various stakeholders (Benham and Daniell, 2016). Oceans and coastal regions are increasingly threatened, degraded or destroyed by human activities such as marine pollution, overfishing or unsustainable extraction of marine resources, as well as by anthropogenic climate change and its associated effects on rising sea levels, increasing ocean temperature, ocean acidification and deoxygenation (IPCC, 2013; UN, 2017). With the rise of resilience science (Holling, 2001) and sustainability science (Kates et al., 2001), integrated approaches are more salient than ever, and interdisciplinarity (Frodeman et al., 2017), transdisciplinarity (Lang et al., 2012) and participatory approaches (Barreteau et al., 2010), are increasingly seen as essential to support decision-making to reconcile human uses of ecosystem services with the conservation of the integrity of these ecosystems.

2The first-ever UN Ocean Conference, held in 2017, emphasised the crucial need for an “integrated, interdisciplinary and cross-sectoral approach, as well as enhanced cooperation, coordination and policy coherence, at all levels” (UN, 2017, p. 2). Similarly, the UN Decade of Ocean Sciences for Sustainable Development, which runs from 2021 to 2030, seeks to “mobilise, stimulate and coordinate interdisciplinary research efforts” (UN, 2019, p. 8).

3Integrated coastal zone management (ICZM) and marine spatial planning (MSP) are the two main instruments that have been created to address critical issues in the coastal zone. They illustrate the move towards a more integrated research community on global change (Mooney et al., 2013) as well as a renewal of science policy in the coastal zone, which should be considered as a “governance framework” (Bremer and Glavovic, 2013). Mooney et al. (2013) described the evolution of the main global environmental research programmes – the International Geosphere-Biosphere Programme (IGBP), the International Human Dimensions Programme on Global Environmental Change, (IHDP), etc., following the creation of the Intergovernmental Panel on Climate Change (IPCC) in 1988, eventually merging into the Future Earth platform in 2012. In this context, research is becoming more interdisciplinary – in particular between the vast spheres or “two cultures” (Snow, 1959) of the natural sciences and the social sciences – more participatory and collaborative, involving more non-academic stakeholders; it is also becoming more solution-oriented, with a view to helping decision-making (Future Earth 2025 vision).

4Examples of participatory governance are described elsewhere in this handbook (see chapter 13), as are innovative tools that promote interactions between communities, stakeholders and governmental organisations in the MSP context in the tropical Atlantic. This chapter will focus on interdisciplinarity through questions that can be applied to MSP, but that are also of broader interest for any type of emerging instrument that aims to take into account the complexity of so-called socio-ecological systems (Liu et al., 2007; Ostrom, 2009).

5The chapter starts with a definition of the concepts: what is interdisciplinarity? Is it something that lies between multi- and transdisciplinarity? Or between discipline and indiscipline? What is the difference between true or superficial, broad or narrow, interdisciplinarity? Which seems most appropriate for MSP? The chapter then looks at the reasons for the need for interdisciplinarity, given the complexity of the challenges and the context of the Anthropocene. It then explores the barriers to true interdisciplinarity and possible bridges for building it. Boundary objects and boundary frameworks are essential in this respect, and MSP is a good example. The final section explores the implications of interdisciplinarity, both in epistemological terms – especially with regard to education and training young researchers – and in “philosophical” terms, given the many current forms of inward-looking attitudes and the crucial need for collaboration to address the major challenges we face as a species today.

Interdisciplinarity: what are we talking about?

Between pluri- and trans-

6Pluridisciplinarity, multidisciplinarity, interdisciplinarity, transdisciplinarity ... These terms are often confused and misused, although they refer to very different epistemological definitions and research processes. When I asked F. Conway (Oregon State University, Corvallis, United States) about these terms, I liked the metaphor she used to distinguish them: different types of fruit scattered in their own orchards for “pluri-”; different types of fruit separated in crates but in the same shop for “multi-”; fruits mixed in a fruit salad but still recognisable for “inter-”; and, finally, a smoothie for transdisciplinarity. It is a vision that resembles the scale of interactions between disciplines provided by Blanchard and Vanderlinden (2010) or the four scenarios of combining knowledge described by MacMynowski (2007): from mutual – even conflicting – ignorance to radical transformation through profound interactions. To illustrate this diversity of possible interactions, I will use the example of my laboratory, my institute and my university.

7The University of Brest is multidisciplinary, with its faculties of humanities, social sciences, “hard” sciences (a problematic concept in itself as we will discuss), law, sport, etc., with little interaction between them. In 1997, the laboratories and researchers working on the sea came together to form an institute, the European University for Marine Studies (IUEM), a faculty at the university that is multidisciplinary, but still with little interaction between the various disciplines. Because geographical proximity plays an important role in the construction of interdisciplinarity (Reckers and Hansen, 2015), bringing these scientists together in the same corridors of the same building has stimulated strong interactions and increased interdisciplinary cooperation between scientists from different disciplines: for example, to work on sustainability issues in the Bay of Brest (Ragueneau et al., 2018). In this sense, true interdisciplinarity involves sharing methods, tools and concepts to work together on a common subject, with all disciplines treated equally.

8Transdisciplinarity deserves a special mention, as it has several meanings, which can lead to confusion. Blanchard and Vanderlinden (2010) define it as transcending disciplines, sometimes leading to the creation of a meta-discipline. The smoothie metaphor illustrates this well, conveying the idea that the interactions between disciplines become so strong that it is no longer even possible to recognise the contribution of each to the final outcome. The communication sciences are taken as an example by Wolton (2013), even leading to biases previously attributed to disciplines when these meta-disciplines seek institutional recognition as one discipline. But there is another definition of transdisciplinarity, often used in the field of sustainability science, which involves working with people outside academia: communities, stakeholders, governmental and non-governmental organisations, etc. Such a definition is used by Lang et al. (2012) and many other researchers, as well as in many official documents promoting integrated approaches (Future Earth platform, UN documents, EU calls for projects, EU, etc.). Action research is an example of this transdisciplinarity, as illustrated in the Future Earth knowledge-action networks (KANs).

9Pohl (2011) has provided a good overview of transdisciplinary definitions and approaches, in which transdisciplinarity involves crossing disciplinary boundaries and may, in addition, involve some work with external stakeholders. Or not – and this is where confusion can arise. For Benham and Daniell (2016), it is both the transcendence of disciplines and the engagement with stakeholders around societal problems – to solve complex issues and provide support in decision-making – that distinguish transdisciplinary from interdisciplinary approaches. But at the same time, they note: “Transdisciplinary research, when undertaken in a participatory manner with stakeholders (i.e. transdisciplinary and participatory research), can inform public decision-making and offer a new approach to understanding complex problems.” So is transdisciplinarity the sum of interdisciplinarity and stakeholder engagement? Given the plurality of definitions, it seems preferable that each researcher defines from the outset the meaning in which he or she will use this term and, above all, that the term transdisciplinarity is not used for all purposes, otherwise it will quickly become a “catch-all” term and lose its force, like other important concepts in this field (e.g. co-construction or co-production of knowledge).

Why interdisciplinarity?

10Perhaps one way to avoid these difficulties would be to use the term “interdisciplinarity” in a more generic sense, “to cover inter-, multi-, cross-, trans- and other extra-disciplinary frameworks”, as Frodeman and Mitcham (2007) suggest. In fact, these authors call for a “critical interdisciplinarity” that poses the essential question of relevance: knowledge for what purpose?

11Knowledge for knowledge’s sake, first of all. Throughout most of the history of science, this knowledge has been broad: pre-disciplinary rather than interdisciplinary. Specialisation – and especially the separation between the natural sciences and the humanities and social sciences (Descola, 2005) – emerged in the 19th century with industrialisation and the idea of society, leading to the different branches of the natural sciences (physics, chemistry, biology, etc.), the social sciences (sociology, economics, political science, etc.) and the humanities (philosophy, ancient and modern languages, history, art history, etc.). This separation between disciplines was exacerbated in the 20th century (although science and technology have merged for better or worse, leading to a very ambiguous perception of science by society [Stengers, 1997; Jarrige, 2016]). While this has clearly led to major improvements in each branch of knowledge, with both dramatic and exciting consequences for humanity, it also has its drawbacks.

12Two major elements have been lost on this path to specialisation: the ability to deal with complexity and the link with society, with science confined to laboratories. The link with politics was also lost: at the very beginning of the 20th century, Weber clearly distinguished between “the scientist and the politician (Weber, 1919). After the Second World War, the Great Acceleration began and 30 years later, a trend towards rationalisation became widespread with huge impacts on many, if not all, areas of human activities. We became “ruled by numbers” (Supiot, 2015), with even greater losses: as T.S. Eliot asked in his 1934 play, “Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?” In our age, F. Taddei (2018) adds, information has disappeared behind data. All areas of life are affected, including those that one might imagine to be most immune to this trend: law, healthcare, education, etc. Science is no exception: the notions of expertise, of excellence itself (necessarily disciplinary), of objectivity and neutrality are a major epistemological component of science.

13Yet over the last two to three decades, a notable shift has emerged, with increasing calls for interdisciplinarity in order to address complexity, linking fields rather than separating them (Morin, 2005). The planet’s entry into the Anthropocene (Crutzen, 2002) is not unconnected to this. Indeed, interdisciplinarity is increasingly seen by science and society as an important means of dealing with the complex problems we face, particularly those at the interface between humans and nature (Klein, 2004). Integrating different types of knowledge is seen not only as a way to better understand this complexity, but also to inform public policy (Frodeman and Mitcham, 2007). Many argue that we have entered so-called “postnormal times” (Sardar, 2010) characterised by chaos, complexity and uncertainty. In this context, in which “facts are uncertain, values are contested, stakes are high and decisions are urgent”, policymakers and managers are under pressure and desperately need new approaches that could help inform their decisions (Benham and Daniell, 2016, citing Funtowicz and Ravetz, 1993). Interdisciplinary, participatory approaches involving different stakeholders are the premise of these systems approaches, whether they are called transdisciplinary (Benham and Daniell, 2016) or critical interdisciplinary approaches (Frodeman and Mitcham, 2007).

14Unfortunately, the challenge of achieving true interdisciplinarity is proportional to its promise.

Between narrow and wide interdisciplinarity

15Let us start by exploring the different degrees of interdisciplinarity – narrow or broad – in different academic disciplines. The move towards specialised disciplines in the 20th century was probably necessary. As Frodeman and Mitcham (2007) state, “this analytical and disciplinary approach has advanced our understanding of nature and contributed to the development of technological power” – again, for better or worse. But it is problematic that disciplinarity is often seen – or even developed – in opposition to interdisciplinarity (although philosophers such as Heidegger have developed a complementary thesis: “compartmentalisation does not split one science off from another ... it yields a border traffic between them” [Heidegger, 1977]). Increasing specialisation has led to two major, perhaps unexpected, problems: (1) Instead of enriching points of view, interdisciplinarity between relatively close scientific fields (e.g. within the natural sciences or the social sciences, or even between different subfields such as biology), what J. Kelly (1996) would call narrow interdisciplinarity, has led to an ever larger number of disciplines and to ever narrower fields of investigation: physics and geology merged into geophysics, biology and chemistry into biochemistry, etc., creating yet “more regional ontologies” (Frodeman and Mitcham, 2007). (2) Specialisation has become so strong in the different disciplines that “border traffic” has become extremely difficult to undertake.

16In my case, I am a biogeochemist, a narrow interdisciplinary field, perhaps transdisciplinary in the sense of Blanchard and Vanderlinden (2010), with a focus on the silicon cycle. Although I have taken courses on nitrogen cycles, phosphorus cycles or those of other elements, I am a silicon biogeochemist (almost a discipline of itself). So to study the functioning of ecosystems, it is necessary to collaborate with specialists on nitrogen, phosphorus, iron cycles, etc., not to mention scientists with expertise in physics or ecology. Indeed, the field is even more narrow – a biogeochemist specialising in the silicon cycle in a terrestrial environment works in a very different world from a biogeochemist specialising in the study of the marine cycle of this same element. To bridge these fields, I coordinated a Research Training Network (RTN, EU Marie Curie Actions) to foster “interdisciplinary” collaboration between land and marine biogeochemists to work on the silicon cycle along the land–sea continuum (Ragueneau et al., 2010). This same specialisation is true for scientists working on silicon in ocean surface waters and those trying to understand the benthic cycle of silicon or using siliceous debris in sediment cores as a palaeoceanographic proxy for past relationships between climate and ocean productivity; they too work in parallel highly specialised worlds, but would benefit greatly from “interdisciplinary” collaboration, for example, in terms of proxy calibration (Ragueneau et al., 2000)

17I would describe this type of interdisciplinarity as “very narrow”, although it already requires a great deal of time and intellectual effort to be able to collaborate and to understand each other. I will come back to these costs, as they seem essential to consider, both for epistemological and philosophical reasons. Narrow interdisciplinarity, for example, is when marine biogeochemists work with physical oceanographers and/or biologists to explore the functioning of marine ecosystems. This remains in the broad field of natural sciences, and the scientists involved stay in their “comfort zone” where they can talk to each other. As interdisciplinarity becomes increasingly wide, we have to move out of our comfort zones and collaborate with scientists from other spheres, such as the humanities and social sciences.

18For example, experimental archaeologists studying stone age toolmaking may require highly specialised expertise in fields such as physics, chemistry or materials science (Léa, 2020). Several disciplines have even developed from interactions between the natural and social sciences (political ecology, ethnobiology, ecopsychology, etc.): the environmental humanities are also growing rapidly (Bird Rose, 2019). But the vast majority of interactions between the natural and social sciences tend to focus on the Great Acceleration and our entry into the Anthropocene (Crutzen, 2002). Mooney et al. (2013) provide a good overview of the evolution of climate change research agendas to integrate the natural and social sciences over the last three decades, culminating in the creation of the Future Earth platform in 2012. They demonstrate the crucial role of global climate and biodiversity assessments (creation of the IPCC in 1988, the Global Biodiversity Assessment in 1995, the Millennium Ecosystem Assessment in 2005) and of key disciplines such as geography, which was pre-adapted to interdisciplinary studies, in the development of programmes and funding for these large integrated programmes.

19These authors also describe the birth of sustainability science (Kates et al., 2001) and the tremendous increase in publications in this field, around the notions of socio-ecological systems (Liu et al., 2007) and adaptive co-management (Kofinas, 2009). As noted above, exploring the functioning and trajectories of socio-ecological systems requires dialogue between these spheres, particularly to explore the links between humans and nature, and between social and biophysical models of socio-ecological conceptual frameworks (Ostrom, 2009; Collins et al., 2010; Bretagnolle et al., 2019). The same is true when considering the use of instruments such as ICZM and MSP. Of course, the enormous time and intellectual cost of engaging in such collaborations between these “two cultures” is equally evident (Snow, 1959, see below).

20Interdisciplinarity becomes even broader when it becomes critical or transdisciplinary – when it leaves the campus and seeks collaborations with the “real world” outside the academic environment. This requires a further step: that scientists recognise that knowledge is distributed across all parts of society and that the hybridisation of knowledge is necessary to inform decision-making in times of uncertainty (Pestre, 2013; Zanotti and Palomino-Schalscha, 2016).

Between true and superficial interdisciplinarity

21It is important to note that this shift in research towards interdisciplinary integration to address major challenges such as climate change remains highly theoretical. While there are many calls for interdisciplinarity, this does not necessarily mean that true interdisciplinarity is actually being achieved (Nielsen and D’Haen, 2014). For example, an analysis of the IPCC reports published only a decade ago has shown that interdisciplinarity remains very narrow, typically confined to the natural and climate sciences, with very few forays into the qualitative social sciences (Bjurström and Polk, 2011). I will return to the difficulties of integrating disciplines with dissimilar epistemologies in the next section, but first want to emphasise the definition of “true interdisciplinarity”.

22By true interdisciplinarity I mean that different disciplines are included in more than a superficial way or just to play a “service” role. The latter is nicely described in Viseu (2015), who reports on her difficult integration as a sociologist in a medical research institute and describes a context in which the social sciences are allowed to observe what is done, but not to disturb it. In this case, social scientists are mainly seen as facilitators of the dialogue between (“real”) scientists and society. This “service” role is also present when social scientists (or humanities scholars) are called upon to study only perceptions or acceptability. As Allmendinger et al. (2013) argue in a note on the EU Horizon 2020 initiative: “The role of the humanities and social sciences should not be simply to help science and business reduce public resistance to or increase acceptance of scientific and technological innovations.” It is more difficult to document superficial interdisciplinarity, but this relates to the list of challenges discussed below, as it has long reinforced the lack of trust between the natural sciences and the social sciences. There are many accounts of social scientists or humanities scholars being called 24 hours before a project submission deadline just to tick a box, or simply being asked to study perceptions and representations of this or that research object or technological innovation (Chlous, 2014). This so-called interdisciplinarity is cosmetic when social scientists are not asked how their research questions can be integrated into the project or, better, how they could actually engage with the project with their own research questions as a contribution to the overall problem at hand.

23In contrast, true interdisciplinarity requires that (1) all research components and researchers are treated equally, from the design of the project to the analysis of the results and their dissemination (Allmendinger et al., 2013), (2) appropriate communication between disciplines (which is often lacking, see Nielsen and D’Haen, 2014) is ensured throughout the research process, both with regard to research results and research methods, and (3) perhaps most challenging, integration is ensured through the development of methods, tools and concepts that allow for the synthesis of knowledge across very heterogeneous data, approaches, and sometimes even schools of thought. In this respect, a major difference between the natural sciences and the humanities and social sciences lies in the qualitative/quantitative debate and the integration of these approaches; this is crucial and will form a major part of the last section of this chapter.

24The next section will explore the factors that hinder such true interdisciplinarity, before providing some avenues for fostering it; firstly, through boundary objects and boundary frameworks, and secondly and perhaps most importantly, beyond approaches through the inclusion of epistemological and philosophical considerations to demonstrate how crucial it is that we succeed in truly developing these integrated approaches. The obstacles are so numerous and so strong that a veritable “indiscipline” will be required if we are to succeed in this endeavour (Wolton, 2013).

Barriers and bridges to true interdisciplinarity

25There is extensive literature on barriers to interdisciplinarity. It is interesting to note, as MacMynowski (2007) has pointed out, that while the need for more and better interdisciplinarity has emerged in environmental science literature, the discussion barely refers to the decades of extensive literature on interdisciplinarity in science and technology studies (STS).

26In the scientific literature on global change, explanations for the lack of interdisciplinarity fall into different categories, ranging from epistemological considerations to problems of organising research and education on campus. In terms of epistemology and ontology, the biophysical and social sciences simply belong to two different cultures (Snow, 1959), with distinct concepts, methods and schools of thought. The discourses, with their different “jargon”, are extremely difficult to reconcile (Wear, 1999). In terms of structural problems in research, researchers refer to challenges in the evaluation process as well as in funding. In education, universities are often organised in disciplinary silos, which prevents cross-fertilisation (Hart et al., 2015). Young researchers are recruited from within recognised disciplines, and it is widely accepted that the breadth of interdisciplinarity cannot replace the depth or even excellence of disciplinary training. This debate between “breadth” and “depth” is a real divide between those for and against the idea of interdisciplinary education (Fischer et al., 2011). Time is another major constraint, as it is sorely lacking in our period of acceleration (Rosa, 2012), although it is absolutely necessary to allow for the learning and trust-building required by these interactions (Strang, 2009). I will come back to this aspect of time, because underlying this is the very organisation of our research and education system and the priorities that need to be rediscussed between researchers and funders/decisionmakers.

27While environmental researchers exploring interdisciplinarity have focused on these aspects, STS researchers have conducted investigations into disciplines and disciplinary migration. What is a discipline? What authority is associated with a given discipline? Why are disciplines hierarchical? What power lies behind such a hierarchy? What is their status in the academy and in society? How does these hinder interactions between the social and biophysical sciences? Power and knowledge are closely linked (Foucault, 1980; Mazé et al., 2017) and this has profound implications for our discussion of interdisciplinarity between these two major spheres of scientific research as well as at the interface between science and society (MacMynowski, 2007).

28Indeed, a major obstacle to interactions between some of the humanities and social sciences and the so-called “hard” sciences is the separation between the qualitative and the quantitative, which reflects different worldviews, scientific status and power. At school (at least in France), if you were a good student, you were encouraged to take maths or physics. If you were a bit less good, you took chemistry. If you weren’t good at science, you took economics or geography, which still involve numbers. If not, well ... you might study foreign languages (with their own hierarchy: German if you were good, Spanish if not), literature or sociology. This hierarchy clearly reflects the status of these disciplines and their social recognition. As mentioned above, today we are governed by numbers (Supiot, 2015). Qualitative analyses have been gradually rejected, mainly because they are subjective, whereas data, the “real science”, is objective and approaching the “truth”. MacMynowski (2007) cites this tendency in key authors in the field of STS: “A claim to pure objectivity is a claim to know the ‘truth’, and thus, a claim to authority and power (Haraway, 1992, Merchant, 1992, Feyerabrand, 1993).” It should be noted that this divergence between qualitative and quantitative also exists within the field of social sciences, where quantitative analyses (e.g. closed questionnaires) are clearly favoured over more qualitative methods (e.g. interviews), which are believed to provide less rigorous results – even the same person may give inconsistent, or even contradictory, results during an interview (Bercht, 2021). Disciplines with rational and quantitative methods are also clearly prioritised in discussions on global change over more human and qualitative analyses (Stoknes, 2014).

29These assumptions reflect the different nature of the objects of study of the natural sciences and the humanities and social sciences. Nature has long been considered comprehensible and able to be described by numbers and regular laws, in a Cartesian and deductive approach, with working hypotheses that can be tested experimentally. In contrast, humans, who are characterised by great complexity, emotions and values, cannot be tested experimentally, which prevents purely rational analysis. Asking a Cartesian naturalist to engage with a humanities scholar or social scientist who takes humans and society as research subjects can make biophysicists despair (MacMynowski, 2007), as Bradshaw and Bekoff (2001) perfectly summarise: “Integrating biophysical and social sciences means bringing back the very concepts and attributes (e.g. subjective experience) that, by their historic exclusion from science, defined science. Incorporating social sciences into biophysical studies has brought attention to not only the interactions between humans and ecological systems, but also to how science functions as part of a larger system of knowledge, nature and society.”

30Reflecting on the interactions between the natural and human sciences refers directly to these questions of power, hierarchy, authority and, above all, the place of knowledge in society and the place of researchers in the quest for solutions to the major problems we confront, particularly at the interface between humans and nature. It is clear that environmental and social problems can no longer be treated separately (Chakravarty et al., 2009; Ragueneau, 2020). Nature cannot be described by simple mathematical laws in these postnormal times (Funtowicz and Ravetz, 1993), nor can humans be considered as purely rational and conscious (Kahneman, 2012) or even neuronal (Changeux, 2012). Complexity is omnipresent, and tenfold when it comes to socio-ecological systems. The climate system and the problem of climate change perfectly illustrate the need for the better integration of qualitative social sciences with natural sciences, especially climate science (Jasanoff, 2010). Yet STS and critical climate research have shown that climate studies too often ignore the qualitative and interpretive dimension that is essential for understanding the political and ethical dimensions of climate change (Jasanoff, 2010; Klepp and Chavez-Rodriguez, 2018). Issues around the social inequality exacerbated by climate change – between poor and rich, the Global South and North, men and women, past, present and future generations – are overshadowed by the search for technological solutions, notably in the form of green or blue growth (Baer et al., 2008; Ragueneau, 2020). A similar debate is taking place regarding instruments such as MSP, questions around whether it should be used as an economic tool to maximise the use of the environment and coastal resources in a blue growth perspective, or, in a more radical perspective, as a policy tool to improve the well-being of local communities, as described by Flannery et al. (2016).

31Researchers reviewing the IPCC reports may lament the lack of lead authors in the social sciences – even in Working Group II on Impacts, Adaptation and Vulnerability (Victor, 2015). They may also note the predominance of natural science and neoclassical economics in broader climate studies (Stoknes, 2014), neglecting human behaviour, so critically important though hard to grasp (see the environmental psychosociology approach developed by Gifford, 1987). Flannery et al. (2016) report that “insufficient attention is paid to the wide range of potential distributional impacts caused and tolerated by an uncritical MSP approach”. In fact, only a fifth of the 1200 or so articles on MSP these authors reviewed (in Scopus) came from the social sciences, only a handful of which took a critical stance. More often than not, as with climate, a positivist tradition of rational natural resource management is clearly dominant, without really exploring who actually benefits from MSP as a new form of coastal management: “without a wider appreciation of the social and distributive impacts, we may end up adopting systems of MSP that are socially regressive and even possibly ‘evil’, at least as used by Baum (2011) to indicate neglecting the needs of the vulnerable” (Flannery et al., 2016). In this special issue on MSP of the journal Planning Theory & Practice, it is clearly stated that these risks can be limited by using a participatory approach, involving all stakeholders and adopting a flexible planning process (Kelly, 2016, in Flannery et al., 2016).

32This very important aspect will be valuable in moving from barriers to bridges to interdisciplinarity, in particular through the idea of “boundary work” and the co-production of knowledge. In fact, MacMynowski (2007) reminds us that the need for interdisciplinarity goes back almost a century: before the dawn of the Anthropocene and the postnormal era, although our current context has reinforced the need for an integrated approach to respond to urgent societal challenges. The barriers to interdisciplinarity discussed above were actually identified long ago (e.g. Chubin, 1976). These obstacles that slow down the “border traffic” (Heidegger, 1977) between disciplines have been explored more recently by STS researchers seeking ways to transcend them and facilitate interactions between disciplines. This is particularly the case of those working on interfaces and boundaries, who analyse “the acts and structures that create, maintain and break down boundaries” (see Klein, 1996, for a review). Boundary work can be applied to the intersection between disciplines (Star and Griesemeier, 1989; Klein, 1996), or between people and organisations, or between science and society (see the pioneering work of Gieryn, 1983, or Jasanoff, 1987 for work between science and policy). It can also be applied to joint work between academics and Indigenous communities to foster intercultural research that truly takes “different ways of knowing” seriously (Zanotti and Palomino-Schalscha, 2016), or between art and science, to encourage different ways of exploring an object or concept and challenge these different approaches to complexity, uncertainty, creativity (Benessia et al., 2012).

33Mattor et al. (2014) have demonstrated the utility of boundary work as applied to the study of environmental governance. They discuss how boundary concepts, defined as “loose concepts that create alliances between fields of knowledge and professional domains while protecting the authority and legitimacy of the participants’ home field” (Löwy, 1992), helped them to develop a common language and shared understanding across very different disciplines, including facilitating their subsequent work beyond academia. They developed a boundary object (Star, 2010) – in the form of a theoretical governance framework – to strengthen integration between disciplines, to take into account the different factors affecting environmental governance in their region and to better account for the crucial roles of power, knowledge and scale in this governance. Moreover, they highlight how fortunate they were to have a favourable external and internal boundary framework to transcend the institutional and logistical barriers identified by Morse et al. (2007), both for research and for education/training.

34The “Planning in a liquid world with tropical stakes” (Paddle) project is an excellent example of such a boundary framework, creating the conditions for working at different interfaces because of its interdisciplinary structure, because it is part of the EU “Research and Innovation Staff Exchange” (RISE) programme to promote cross-border and cross-sectoral collaboration, and because it focuses on MSP.

35MSP itself is a good example of a boundary framework that promotes cross-sectoral activities: it encourages vertically integrated work between multiple stakeholders (an area’s managers, users, policymakers) working together horizontally in the different sectors of maritime activities (shipping, ports, oil and gas exploitation, aquaculture, fisheries, offshore energy production, tourism, nature protection, etc.). Such integration involves working across boundaries at professional, geographical, institutional and administrative levels. This cross-sectoral integration is closely related to that of stakeholder involvement and participatory governance, as discussed in Toonen et al. (see chapter 13).

36The EU RISE programme is also a boundary framework, as it encourages international and intersectoral collaborations. In the case of the Paddle project, it provides an excellent context for exploring the idea of implementing MSP – an instrument developed in the Global North that includes approaches such as integrated coastal zone management to improve the sustainability of oceans and coastal waters – in countries in the Global South through practices such as secondments of scientists, international conferences, or training and capacity-building workshops. In this sense, it participates in the ongoing “decolonisation process” (Ferdinand, 2019; Zanotti and Palomino-Schalscha, 2016) that aims to offer attention and respect for plural epistemologies and ontologies, well beyond the Western ontology based on a clear separation between nature and culture (see also Escobar, 2018).

37To explore these cross-sectoral and cross-cultural dimensions of MSP, the Paddle project itself is organised as a boundary framework that fosters inter- and transdisciplinary approaches. The project consists of disciplinary work packages (e.g. WP 2 on ecological processes, WP 3 on policy and governance), but interdisciplinarity is encouraged through secondments, workshops and a dedicated WP for interdisciplinary analysis (WP 5). Transdisciplinarity plays a particular role in WP 4 (challenges and solutions) at study sites in Senegal, Cabo Verde and Brazil, where local scientists are actively working with local stakeholders.

38Several tools have been used as boundary objects to reinforce inter- and transdisciplinary approaches during the Paddle project, demonstrating their relevance for this purpose. They can be found in the chapters of this handbook (Brunel and Lanco Bertrand, chapter 15; Soudant et al., chapter 5; Trouillet et al., chapter 10), but a few examples can be provided here for the purpose of illustration. Decision support tools are widely used in MSP (Pınarbaşı et al., 2017) and have been studied by both natural scientists and social scientists in the Paddle project, resulting in guidance that identifies their usefulness as well as potential biases related to data availability, ethics and lack of stakeholder participation (e.g. Brunel and Lanco Bertrand, chapter 15). Similarly, geographers and lawyers have worked together to produce a cartographic atlas of environmental law in West Africa (Le Tixerant et al., 2020). The exploration of its use by different governmental and non-governmental institutions has demonstrated the potential of such a spatial projection of jurisdictions in the context of the development of MSP in Senegal, notably for monitoring purposes. But it also reveals that such maps have not yet been widely used, for reasons that need further exploration: whether this is due to the fact that MSP is still not effective in Senegal, to the status of maps, which have proven to be excellent boundary objects for fostering stakeholder involvement in the context of ICZM (Ritchards et al., 2018), or to the power that a map holds (Harley, 2008), which may constitute a barrier to collaboration and knowledge sharing (Le Tixerant et al., 2020).

Implications for education and training

39The organisation of universities into disciplinary silos is recognised as a major obstacle to interdisciplinarity (Hart et al., 2015). Some sociologists and philosophers have harsh words against universities, considering that academic departments produce ignorant specialists, blind intelligence (Morin, 2005), or even mediocrity (Chomsky, 2010). Rosa and Marshlis (2002) use the term “trained incapacities” to identify the problem that specialised disciplinary training, while critical, is proving insufficient to solve increasingly complex scientific (Sillitoe, 2004) and societal (Klein, 2004) problems.

40Interdisciplinary training is intended to facilitate complex problem-solving and is itself complex; this complexity should be embodied throughout the research and education process. What is considered an obstacle for some may be a bridge for others. Above all, it is a personal and ontological way of looking at research, striking a balance between discipline and indiscipline, between safety and risk-taking, between short-term and long-term, between depth and breadth, between applied and fundamental research. Currently students are trained to prioritise discipline, safety, the short-term and depth in order to become researchers who will approach, if not the truth, then at least excellence in fundamental research. How can we reconcile the need for training specialists who allow major advances in their field with the need to address increasingly complex scientific and – perhaps even more importantly in the Anthropocene – societal problems? To embody complexity, it is important to move away from these binary oppositions and find the best balance between these needs, depending on the students, the issue to be addressed and the academic/programme constraints.

41The cultural context is crucial in relation to these constraints, as I found out when I visited several sustainability centres in the United States and Canada in 2016 to learn more about how they stimulate interdisciplinarity in both research and education. France, for example, has a very centralised organisation, with a strong emphasis on linear curricula, degrees and excellence, perhaps a result of a system in which universities are considered second class in relation to the “grandes écoles” that select the best students. Equally, a clear priority is given to intellectual professions over vocational training: the aforementioned opposition between depth and breadth and basic and applied research represent very strong barriers to inter- and transdisciplinary education in France. In contrast, less centralised countries such as the United States, where a more pragmatic individual experience and less linear curricula are recognised and students can choose their courses almost “à la carte”, may offer a more favourable context for interdisciplinary education. Indeed, it was in the United States and countries with an Anglo-Saxon tradition that the first sustainability centres emerged some 15 years ago (Hart et al., 2015). In North America, Australia and northern Europe, there seems to be more of a perspective that a breadth of education can allow high employment potential outside and even within the academy, and applied research is no longer seen as opposed to basic research, but rather part of a continuum from scientific discovery to application for societal needs with mutual benefits, whereas in France, strong indiscipline is needed to overcome institutional and cultural barriers against interdisciplinarity (Wolton, 2013).

42Yet it is important to note that even in countries where the context appears to be more favourable, as the US-based Morse et al. (2007) have noted: “many academic institutions continue to address critical topics such as biodiversity conservation and sustainable development through disciplinary approaches”. This is often because “students are required to meet traditional departmental degree requirements” and, I would add, because the research system still favours disciplinary research, so it is still very risky for students to take interdisciplinary courses or for universities to take their students down uncertain avenues. This can be seen in the way young researchers are recruited in academia or in scientific institutes, in the way careers are evaluated for promotion, or in the fact that publications are still a major criterion in the evaluation system. Of course, it is easier to publish in one’s own discipline, both because we have been trained that way and because there are many more disciplinary journals than interdisciplinary opportunities to publish outside one’s field. Any attempt to foster interdisciplinarity during the training of young researchers, or any exploration of ways to stimulate interdisciplinarity must thus be accompanied by real efforts to change the research system and its evaluation so that it can accommodate this interdisciplinarity and embrace the complexity of science in a postnormal age.

43Things are slowly changing as academics and civil society recognise the need for interdisciplinary education to prepare future managers, scientists and leaders to solve complex socio-environmental problems (Ewel, 2001). Early calls to train scientists in sustainability were made 20 years ago (Clarke, 2002), and today courses are offered on issues (climate change, biodiversity conservation, etc.) that involve different disciplines as well as different perspectives (scientists, managers, journalists, policymakers, artists, etc.). MSP can represent a boundary framework that provides an ideal support for interdisciplinary training, a necessary step to strengthen the development of this instrument (Gissi and de Vivero, 2016).

44Over the past 15 years, universities have increasingly provided “education at the boundary” between disciplines in postgraduate and doctoral programmes. For example, Morse et al. (2007) describe their experience of launching an interdisciplinary postgraduate programme, noting the barriers they encountered and the bridges that helped them overcome these barriers at individual, disciplinary and programme levels, and providing a set of recommendations for conducting postgraduate interdisciplinary research. These include individual accountability, developing formal and informal communication strategies (especially to address rather than avoid conflict), careful consideration of team building, mentoring, joint goal setting, focus and framing of problems, addressing issues of spatial and temporal scale, and respecting discipline-specific time constraints.

45To overcome the barriers we have described, these authors emphasise several ways to bring the crucial personal and human dimension to the epistemological and institutional components of the problem: personal vision, commitment, working across boundaries, collaborating with others, etc. As L. Cianelli, who developed a wonderful interdisciplinary graduate programme at Oregon State University (United States) told me: “Sometimes it’s easier to get disciplines to work together than it is to get people to work together.” It is all about being willing and able to step outside of our comfort zone. Teaching students how to work together in our competitive world becomes crucial, bringing us to the last section of this chapter, which stresses the importance of interdisciplinarity in these uncertain times.

A look back at the importance of inter- and transdisciplinary research

46Overcoming the challenges and obstacles to the development of interdisciplinarity, in education as well as research, is exactly what makes it crucial. It is a form of resistance to the unsustainable path we are on, which is causing environmental degradation, increasing inequality and multiplying inward-looking attitudes, which are endangering democracy in many parts of the world (Ragueneau, 2020).

47Time is perhaps the first element that comes to mind. Interdisciplinarity is a time-consuming activity (Strang, 2009); the time needed to step aside and meet the “other”. The “other” that comes from another discipline, or even from outside the academic world if our critical understanding of interdisciplinarity is taken to include transdisciplinarity (Frodeman and Mitcham, 2007). The further the distance from the “other”, the longer it will take for discussion, mutual understanding, and trust building. Moreover, interdisciplinarity cannot be achieved without comparative epistemology, without in-depth analysis of the conditions of knowledge production in the different disciplines (Wolton, 2013) – which requires additional time. Unfortunately, in these times of alienation and acceleration there is a feeling of perpetual time famine (Rosa, 2012), and the scientific community is no exception. Researchers must constantly look for more projects and more funding, publish more articles, speak at more conferences, obtain more patents. “Slow science” (see Alleva, 2006), like “slow food” or “slow cities”, would be a response to resist the Great Acceleration, which is so closely linked to our system. It would leave more room (and time!) for collaboration rather than competition, for quality rather than quantity. It would leave more time for interdisciplinarity.

48Competition is the social engine of acceleration. Thus, the question of time reflects our modern organisation of life, our vision of progress (Rosa, 2012). Resisting acceleration through slow science means moving from competition to collaboration. Interdisciplinarity is an excellent way to train researchers, young and old, to develop all the faculties needed to work with this strange “other”: intellectual flexibility, patience, willingness to negotiate, skills in communication, trust in collective intelligence. It is also an excellent school in humility, desperately needed to counteract “Homo Deus” (Harari, 2017), requiring each of us to acknowledge our shortcomings, lack of ability and the crucial need for complementary expertise, with some sociologists of science even calling for an “accepted policy of ignorance” (Pestre, 2013). This is probably not the quickest way to boost your scientific career, but it could contribute to a shift from data and information to knowledge and wisdom (as per T.S. Eliot), so urgently needed in the transition to greater sustainability (Ragueneau, 2020).

49The road is long, but it is of primary importance to resist the rise of populism all over the world that is riding the wave of short-termism and simplicity. As E. Ostrom (2005, cited in Lara, 2005) says: “complex problems require complex solutions and explanations”. Engaging in interdisciplinary collaboration is a powerful way to escape the simplistic reasoning of populist leaders who propose “solutions” that ultimately lead to nationalism, totalitarianism and/or war (Arendt, 1982). Interdisciplinarity, in this sense, can contribute to the quest for a common world, with strong implications for freedom (see Arendt, 1993). It is important that seeking this common world has a strong international dimension, especially between modern and non-modern cultures. As Wolton (2013) argues, there can be no interdisciplinarity without a comparative approach to the development of scientific fields in different cultural contexts. And if we take the broader meaning of interdisciplinarity to include science–society interactions, it is essential to recognise that non-modern cultures have much to say and likely to teach to modern science, which tends to grant itself a monopoly on knowledge (Escobar, 2018). In his book Thinking-Feeling with the Earth, A. Escobar (2018) demonstrates the benefits of joint efforts between civil society movements and researchers towards sustainability in Latin America. He argues that modern science should be analysed by political ontology, in the vein of cultural studies, critical geography and political ecology, contributing to the decolonisation movement in ecology (Ferdinand, 2019).

50What is sorely lacking in this search for a common world is a new grand narrative, something “bigger than ourselves”, but different from a religion, an empire or capitalism; different from the anthropological options between transhumanism or the collapse of civilisation (Rey, 2018) or the political pseudo choice between nationalism or unbridled globalisation (Fraser, 2017). Interdisciplinarity between the two major spheres of scientific research (natural sciences and humanities and social sciences) as well as work at the interface between science and society can contribute to this quest by helping us to escape from (Ragueneau, 2020): (1) rationalisation and governance by numbers (Supiot, 2015), (2) the dominance of quantity over quality (see discussion on the qualitative/quantitative divide, Nielsen and D’Haen, 2014; Bercht, 2021), (3) the short-term vision and commodification of knowledge and universities (Chomsky, 2010), and more generally, (4) the absence of a global political vision, which is not masked by the positivist vision of our supposed salvation by technoscience (Rey, 2018).

51However, neither interdisciplinarity alone, nor the noble ideas of transdisciplinarity, collaboration, co-production of knowledge, participation – although essential in the sustainability transition – will be sufficient. As D. Pestre (2013) argues, these approaches must not hide the dark side of power asymmetries. Domination, influence, interests ... it would be idealistic to forget these darker aspects as we engage in collaborative, inter- and transdisciplinary processes aimed at transforming our societies towards sustainability (Mazé and Ragueneau, 2022). Indeed, this makes the debates around MSP so crucial: should it be a predominantly rational and scientific instrument aiming to maximise the use of coastal waters in a blue growth perspective, or should it be more radical, with a more human and social perspective aiming to rebalance power between local communities and different stakeholders (Flannery et al., 2016)?

52The Paddle project is a forum for such debates (for example, at the WP 3 workshop held in Tamandaré, Brazil, in November 2019). Beyond seeking true interdisciplinarity, it forces each of us to reflect on science–society interactions, on our position in power games and on the political vision of MSP. This is critical in these uncertain times of the Anthropocene when our responsibility as scientists is engaged (Paasche and Österblom, 2019; Ragueneau et al., 2020) in a context of decolonial ecology (Ferdinand, 2019) and the search for increased sustainability for all, human and non-human alike.