Several years ago, International Relations of the Asia-Pacific (IRAP) published two special issues, investigating the development of international relations (IR) theory worldwide (Acharya and Buzan et al. 2007; Acharya and Buzan 2010; Alagappa et al. 2011). The scholars who participated in these projects set out to discuss whether IR theory existed at all, outside Western countries. Some admitted that interest in theory was low in Japan and other Asian countries. They pointed out that IR studies in Asia tended to emphasize historical analyses and area studies, and concluded that this research style was a major reason for the absence of theory (e.g., Acharya and Buzan et al. 2007; Yamamoto 2011). Meanwhile, other scholars identified Asian thoughts related to IR as distinctive. In the case of Japan, researchers perused the writings of modern intellectuals and revealed that they embraced a variety of ideas about contemporary international relations and the world order. Some researchers viewed these discourses as unique in the context of recent IR theoretical studies (e.g., Inoguchi 2007). Others were more cautious about labelling these ideas original and/or referring to them as academic theories (e.g., Chen 2012; Shimizu 2015). Since the publication of the two special issues mentioned above, scholars have grown more interested in the global plurality of IR studies and frustrated with US dominance of the discipline (Eun 2016; Turton 2016; Wemheuer-Vogelaar et al. 2016).

As the diversity of IR studies has been emphasized over the past decade, scholars have been less unanimous in using the word “theory.” Roughly five types of theory can be identified in the literature.

First, some scholars emphasize social and cultural differences across regions and countries. They attempt to develop region/country-specific theories that are separable from IR theories based on Western culture (e.g., Zhao 2006; Inoguchi 2007; Yan 2008). Regarding theory as culture-dependent form of contemplation and wisdom derived from the historical experiences of each region or country, these scholars are interested in forming a variety of schools of IR studies. From this perspective, the traditional theories that underpin IR studies, such as realism and liberalism, are also seen as manifestations of schools developed in the regional contexts of Western countries. This type of theory often draws on a body of classical and modern thought that describes the world order as it should be, such as Confucius, Hobbes, Kant, and the rational assumption in economics. It also refers to world orders that existed in particular regions in the past, such as Greece, China, and Western Europe. As such, these theories are sometimes philosophical and usually play a normative role in advancing IR studies.

A second group of scholars considers that theory integrates various schools into one. They argue that, instead of adhering to a single school, specific to a region or country, theorists should unify various ideas. Acharya (2014, 60, 83) argues that a global IR theory should be developed by incorporating Asian ideas and experiences into existing theory (i.e., Western theory), rather than dismissing the Western-centric approach or defining region/country-based schools in isolation from each other.1 The global IR theory proposed by the second group of scholars could be more universalized by uniting various schools; this would reduce the cultural prejudice pertaining to each school. Meanwhile, since this approach treats global theory as a balanced summation of various local schools, a global theory presented by this type remains normative and is not intrinsically different from the first type, although more protected against local bias and more widely accepted globally.

A third group of scholars considers theory to be a constellation, rather than an integration, of perspectives and paradigms. Sil and Katzenstein (2010, 2011) argue that, instead of creating a universalized theory, various analytic frameworks (each perspective or paradigm) should be appropriately combined within a specific study. The set of analytic frameworks used in a specific case may include IR perspectives, such as realism and liberalism; other social science fields, such as economics and psychology; and the natural sciences (Sil and Katzenstein 2010, 36–37). This approach is called analytic eclecticism. It argues that human society can only be analyzed by investigating phenomena that can be illuminated by intersections between frameworks, such as those between realism and liberalism, or between politics and economics.

The fourth group includes scholars who are more skeptical about the usefulness of traditional IR theory. Lake (2011, 465) calls these IR theories, referred to as “research traditions” in his article, academic sects. He complains that the field of IR studies has wasted time waging theological debates between academic religions. Although he agrees with Sil and Katzenstein that analytic eclecticism is needed for research, unlike them, he overtly discards the lenses of “isms,” such as realism and liberalism, from his eclecticism. In other words, the eclecticism of the fourth type of theory is more eager to be scientific, whereas that of the third type remains more normative. Lake’s clear distinction between the two types of eclecticism has provoked both favorable and unfavorable responses from scholars (e.g., Dunne, Hansen, and Wight et al. 2013).

Despite their disagreement over “isms,” a common emphasis on eclecticism by the third and fourth types of approach stems from their shared recognition that current IR studies are far from being a fully-fledged discipline. On the one hand, since the system of global politics is extremely complicated, none of the single perspectives or methods so far used in IR studies has been able to reveal the mechanisms that drive the world. On the other hand, no one expects a powerful general theory of social analysis, able to survive empirical tests at the level of the natural sciences, to be developed in in the foreseeable future or, indeed, ever. For this reason, the only approach we can adopt is to “continue to have many different partial theories that, at best, provide insight into limited pieces of the overall puzzle of world politics” (Lake 2011, 467). Thus, they consider eclecticism necessary.

The mindset that underpins this kind of eclecticism is pragmatism. The conjunction of two ideas is a logical consequence. Analytic eclecticism uses a combination of approaches chosen from a variety of disciplines. Since no procedure for making that selection has been established, the choice is inevitably made in pragmatic ways, reflecting the particular issue addressed by each researcher. Quoting William James, a typical American pragmatist, Sil and Katzenstein (2010, 45) have argued that “pragmatists seek to bypass unresolvable metaphysical disputes and instead ‘try and interpret each notion by tracing its respective consequences’ in concrete situations” (emphasis added). Likewise, Lake (2011, 471–472) has proposed adopting issue-centered, rather than approach-centered research. He argues that researchers should focus on studying things that matter, and that university classes and the research sections of academic associations should not be organized around research traditions but around topics, such as climate change, war, and economic inequality. In emphasizing the difference between subjects, and the need to tailor each method to its subject, eclectic analysis is a pragmatic approach that provides an interpretation of each case from a general perspective, rather than developing a theory that explains various cases as a whole.

Finally, other researchers have defined “theory” as closely relating to the natural sciences. In a narrow sense, this type of theory indicates social modeling, using mathematics to describe causal relationships.2 By this definition, IR studies have only a single type of theory, described by the common language of mathematics. For scholars who uphold this definition, theoretical research exists, not to engender unique schools, but to develop individual models on a common foundation. The recent emergence of such studies has been encouraged partly by Lake’s unequivocal rejection of “isms.” However, his proposal is only one example of the scientific orientation of social analysis, which can currently be observed in various social science fields. Understandably, some IR theorists who focus on qualitative methods are openly hostile to this approach (e.g., Walt 1999; Mearsheimer and Walt 2013).

Discussions among scholars with different views on the definition of theory often evolve into competitions, in which the superiority of one view or another is contested. By contrast, this paper argues that each of the five ideas described above has its own merits and benefits the development of the discipline. The following sections reveal how each “theory” plays a role in that development. The approach taken in this paper is to provide a different term for each idea, rather than trying to stuff different ideas into the single word, “theory.” The first and second types are referred to as “normative approaches,” the third and fourth as “pragmatic,” and the fifth as “science-oriented.” The following sections describe how these three groups of theory have developed up to the present in Japan. The normative, pragmatic, and science-oriented approaches are explained in that order.

At present, the field of IR studies tends to overvalue empirical research. Major journals prefer reports of empirical results, either quantitative or qualitative, over propositions derived purely from philosophical contemplation and formal models. However, normative arguments that present worldviews and visions are important, particularly because the explanatory power of IR empirical studies remains pitifully weak. In the natural sciences, for example, empirical results in physics and chemistry are often applied to engineering and medicine. By contrast, similar results in IR studies and the social sciences in general are seldom used in policy implementation. This shows that empirical research in IR studies is far from revealing the truth of our society.3 Given the limited ability of empirical research to guide our society toward a better world, normative arguments are essential for ameliorating our problems.

As Yamamoto (2011) describes, issues of the journal Kokusai Seiji have themes that typically reflect the state of the art in Japanese IR studies in each period.4 Kokusai Seiji regularly publishes issues that feature international political thought. During the early days of the Japan Association of International Relations (JAIR), much space was devoted to studies of Western ideas. Motokawa et al. (1962) in the issue, “Kokusai Seiji no Riron to Shiso (Theories and Thoughts in International Politics)” focused on studies of how thinkers, such as Lenin, Jaspers, Niebuhr, and Russel, understood international politics. Two decades later, the focus of the journal was shifting away from Western philosophy. In addition to American and Western international political ideas, Hatsuse et al. (1981) in the issue, “Kokusai Kankei Shiso (International Thought)” gave non-Western ideas equal status, and it included those of Japan, the Islamic world, and ancient India. This trend has been enhanced during recent debates on the plurality of IR studies. Along with articles on Britain, the United States, China, and the Islamic world, Endo et al. (2014) in the issue, “Rekishiteki Bummyaku no naka no Kokusai Seiji Riron (International Political Theory in Historical Context)” include three articles on the case of Japan.

The only article that discussed Japan in the issue of Hatsuse et al. (1981) selected as its topic the Heiwa Mondai Danwa Kai (Peace Study Group), which was a group of intellectuals who discussed policy suggestions for peace (Hook 1981). Meanwhile, an article of three studies regarding Japan in the issue of Endo et al. (2014) chose a topic about the Japanese peace movement (Fujiwara 2014).5 This implies that contributors to these issues noticed that the idea of peace was becoming “something special” in post-World War II Japan, and viewed it as having a significant influence on discourses in Japanese society. In fact, many post-WWII Japanese IR scholars have identified themselves as liberals and been committed to this idea. However, discussions about peace have not merely influenced these liberals. As described below, this national discussion has also deeply affected arguments by Japanese scholars who have positioned themselves in the realist camp. Thus, the influence of this idea has been profound in the Japanese IR community. The rest of this section reveals how peace-related thought in post-World War II Japan (Heiwa Shiso ) has formed a path in the academic discourses of IR studies that is distinct from those of other countries.6

Japan’s peace-related thought has influenced the development of normative arguments in IR studies in three ways (see Yamamoto 2011 for more detail). First, as mentioned above, it has made Japanese realism less obsessed with the tenets of standard Western realism in IR studies. In the 1950s and 1960s, there was a debate in Japan between realism and liberalism (or idealism) about whether Japan should remain allied with the United States or choose to be neutral in the Cold War. Understandably, the realists argued that Japan needed to side with the United States, while the liberals insisted that it should become a neutral country.7 Masataka Kosaka was the most influential realist at the time (and may remain so two decades after he passed away), and he rejected neutrality certainly. However, a closer examination of his argument reveals that he was less one-sided than he presented himself as being. Specifically, he considered values important in diplomatic relations and argued that peace should be the ultimate value pursued by Japan. He wrote:

Undoubtedly, the value that Japan should pursue is absolute peace that is provided in Article 9 of the Japanese Constitution. Thus, I embrace the prohibition of possessing forces in this article as value (Kosaka 1963, 41).

Thus, the most important contribution of neutralism is that it has brought the significance of value to this argument. It is insufficient that Japan’s diplomacy merely ensures the security of Japan. It should be achieved in a way that realizes Japan’s value (Kosaka 1963, 42).8

Kosaka’s argument went beyond strategic considerations, such as the power balance of states and the rational calculation of interest, although these considerations were first principles for him. His argument demonstrates that peace-related thought, as a value, was a constitutive element for not only liberals, but also for scholars who interpreted world politics from a realist perspective.

The liberal aspect of Japanese realists can also be found in later periods. The idea of comprehensive (national) security proposed by Prime Minister Masayoshi Ohira in the late 1970s was typical. This idea enlarged the scope of security from an entirely military matter to one that covered threats to the economy, food, and energy, and also included natural disasters. Kosaka was a member of Ohira’s Comprehensive National Security Study Group and he played a leading role for introducing this idea to the commission. Since then, the report presented by the group in 1980 has become a precedent that is often consulted when the concept of security is discussed in Japan. Kosaka did not stick to the realist orthodoxy that gave military power an exclusive status; instead, he viewed nonmilitary power as significant in international politics. In this respect, his approach to national security overlapped with that of the liberals, who emphasized transnational relations and interdependence in the 1970s and 1980s, rather than structural realism, as presented in Waltz’s 1979 book.

Second, Japanese studies related to international political economy (IPE) were also promoted by peace-related thought in the 1970s and 1980s. Of course, the increased interest in IPE was influenced by the course of world politics at the time, including the relative decline of the United States and soaring oil prices. However, the younger generation of researchers, who were born in the 1940s and working in IPE studies in the 1970s and 1980s, shared important war memories with the older generation. For example, the only factor that induced Takehiko Kamo, a new leader of liberalism, to study IPE was the need to find ways to prevent war. For him, the questions to be solved in IPE were the same as those in security studies. In particular, he considered the dominance of sovereign states in the international system to be a primary cause of war. His IPE inquiries therefore focused on whether or not the widespread influence of non-state actors, low politics, and international integration were able to abolish war.

Finally, peace-related thought continues to influence current Japanese scholars, as demonstrated by their strong interest in the nonmilitary aspects of security. Human security studies are a typical illustration of it. As is well known, the Japanese government and society are active in promoting human security measures. Following the publication of a UNDP report in 1994, the Japanese government took the initiative in establishing the Trust Fund for Human Security in the United Nations in 1999. Encouraged by the mindset of the government and the public, IR researchers in Japan have produced a number of studies on human security (e.g., Higashi 2017). In the education field, they are eager to offer courses and programs that focus on human security. Due to Japan’s pre-1945 war experience, many universities in postwar Japan have avoided offering courses on international security. The shift toward a security concept that accords with peace-related thought has led to a change.

In sum, peace-related thought in post-World War II Japan has engendered a form of realism that is more liberal than those of other countries. To a greater extent than in other parts of the world, in Japan, IPE and the studies of nonstate actors have focused on questions predicated on the traditional interest in war and peace. The scope of security has been broadened to include non-violent means more vigorously than in other countries. Although most of the concepts discussed in this section, such as realism, liberalism, IPE, non-state actors, and human security, are the products of Western IR studies, as I see it, the normative IR argument in Japan is as different from the American variety as the English school is from the American one. Regrettably, Japanese scholars who have advanced this normative argument have not been explicit about how the elements of peace-related thought are woven into their discourses. By presenting itself as an extension of Japan’s post-World War II peace-related thought, the normative argument in Japanese IR studies will introduce another group of normative approaches, alongside those that currently prevail around the world.

As described in the first section, the eclecticism emphasized by Sil and Katzenstein (2010, 2011) and Lake (2011) accompanies a demand for pragmatism. Eclectic analysis is powerful in providing an interpretation for each case from a general perspective. Area studies is the subfield of IR studies that most requires this approach. In Japan, along with historical studies, area studies has produced abundant research outcomes, particularly in relation to Asia. This section explains the way in which the field of Asian studies has traced a unique path in Japan.

Universities in Japan have been enthusiastic about teaching and investigating Asian studies. In education, it is common for universities with departments of political science, economics, and history to open Asian studies programs. In research, university research institutes have led the development of the field; they include the Center for Southeast Asian Studies (CSEAS) at Kyoto University, the Institute for Advanced Studies on Asia (IASA) at the University of Tokyo, and the Research Institute for Languages and Cultures of Asia and Africa at Tokyo University of Foreign Studies.

Outside universities, the Institute of Developing Economies (IDE) has played a special role in developing the field. The IDE was established in 1958 as an incorporated foundation, and is currently operated as an incorporated (independent) administrative agency. In the beginning, it was uncertain whether the new organization would evolve into a body that promoted academic study. The IDE was not administered by the Ministry of Foreign Affairs, but was placed under the jurisdiction of the Ministry of International Trade and Industry (MITI). The organization’s name suggested that it was likely to focus on economics, rather than broader area studies.9 In addition, the supporters who helped to establish the IDE included politicians and business leaders who believed the conservative ideas about Asia that had spread into Japan before 1945. Many of them were interested in using the IDE to tie the Japanese economy to Asian economies again, enhancing business in those countries, rather than developing research on Asia (Karashima 2015, Chapter 5).

Nevertheless, the fact that academics substantially managed the IDE allowed it to pursue academic research as well as market surveys. Seiichi Tobata, a professor emeritus of the University of Tokyo, became the president (Shocho ) of the IDE in 1959. Yoichi Itagaki, Shigeto Kawano, and Noboru Yamamoto— professors who had petitioned Prime Minister Nobusuke Kishi to found a new organization for Asian studies (leading to the establishment of the IDE)—were appointed as senior members. They had a substantial influence on determining the IDE’s research policy. During the early years, IDE research did tend to focus on the economic issues favored by MITI and the business community, such as development and assistance. However, a more comprehensive style of research began to emerge in the mid-1960s, when specialists in broader fields, including political science and anthropology, were included in IDE research (Suehiro 1997, 50-57; Karashima 2015, 180–190).

Two characteristics can be identified in the development of Asian studies in Japan (see also Suehiro 1997, 66-67). First, from the outset, researchers were interested in interdisciplinary Asian studies, a manifestation of eclecticism. For Tobata, it was not sufficient to study economic development alone even if that study aimed at investigating economic issues. He argued that Asian studies should include, not only economic growth, but also various fundamental factors that determine the course of economies, such as law, politics, and religion (Suehiro 1997, 53). The CSEAS approached Asian studies in a similar but more extensive way, including natural sciences, as well as social sciences and humanities. In the 1980s, the CSEAS named its approach Sogo Seitaigaku (total ecology) (Suehiro 1997, 62–63). The IASA’s interdisciplinarity was indicated by its emphasis on studies that traversed national borders. This approach was reflected in its division names, including “pan-Asian economies” and “pan- Asian anthropology,” which were first adopted in 1951. In 1981, IR studies were assigned to the department of pan-Asian studies (IASA 2012).

Second, unlike many social scientists, who imported Western ideas uncritically, researchers in Asian studies were eager for their studies to be original. For example, Yoichi Itagaki, a professor at Hitotsubashi University and the most significant academic at the time of the IDE’s founding, later related that he learned nothing new during his stay in the United States in the late 1950s (Suehiro 1997, 66). The CSEAS’s sense of confidence was reflected in the fact that it gave its studies a distinctive name, Sogo Seitaigaku . Researchers who focused on Asian studies during the early post-World War II period in Japan were not very interested in American-style area studies or modernization theory. In recent years, approaches developed in Western countries, such as comparative politics and development economics, seem to have become more influential than before. However, even today, researchers in Asian studies keep their distance from Western ideas, in comparison with their colleagues in neighboring disciplines.

These two characteristics of Asian studies in Japan, interdisciplinarity and originality, are typified by Yoshikazu Takaya’s research on the world system. Takaya began his academic career by studying agriculture and ecology in Southeast Asia. Absorbing knowledge from various fields, he later came to propose the idea of “world units,” which he used to replace sovereign states as analytical units. Takaya (1993) defined world units as regions where people shared a common worldview; he identified four in Southeast Asia. Later, he modified the definition of “world units” to one based on ecological differences (Takaya 1996). The revised version identified 19 world units around the globe. It seems clear that his flexibility, in changing the definition of world units, reflected the pragmatism required in area studies.

Since his argument was based on a knowledge of ecology, history, and other fields, it was clearly interdisciplinary. Meanwhile, the originality relates to the way in which he consulted previous studies. At first sight, his argument is similar to the world system theory proposed by Immanuel Wallerstein or the civilization-based world history put forward by Arnold J. Toynbee. However, Takaya seldom referred to these Western authors. The references in his book indicate that his argument relied on his own research and previous studies produced by Japanese area specialists. Takaya’s focus on interdisciplinarity and originality was shared by other researchers who, in place of Western literature, valued fieldwork in local areas. The numerous monographs on Asian countries they produced demonstrate this, although it is not possible to discuss this body of work in depth, due to space limitations.

The mindset of Japanese area specialists had a negative effect as well, as their research confidence prevented them from publishing studies in English. As a result, most of their studies were not disseminated to researchers outside Japan, creating a large deficit in the development of Asian studies worldwide, as well as in Japan. Fortunately, the situation has recently changed. The IASA began to publish an English journal, the International Journal of Asian Studies , in 2004, while the IDE launched a book series in English. In addition to an English book series first published in 1966, the CSEAS recently strengthened its offerings by launching another three-book series in English. Since 2012, it has published an English-language journal, Southeast Asian Studies . These are a just few examples that illustrate the trend in Asian Studies across Japan. These changes should allow Japan to become a major point of reference for Asian studies worldwide.

At the start of the second section, I argue that the present state of IR studies remains methodologically underdeveloped, as its research results cannot be applied to public policy with the same level of reliability as those of, for example, pharmacology or engineering. Although this fact should be acknowledged, it does not follow that the search for scientific approaches equivalent to those of the natural sciences should be abandoned. It is uncertain whether social analysis can ever attain the same level of rigidity as physics. Plenty of metaphysical discourses on subjectivity assert that scientific attempts, equivalent to those in the natural sciences, are impossible in the social sciences. In fact, the debates about subjectivity are substantively relevant to disciplines that are seemingly unrelated to these discussions, such as quantum mechanics. However, these arguments merely suggest that the right path to revealing the truth that underlies our society remains unknown, given the current state of our knowledge. The correct strategy must involve humbly pursuing all possible alternatives, rather than abandoning particular approaches. Along with normative arguments and pragmatic approaches, IR research should also be carried out using scienceoriented methods.

As Yamamoto (2011) described, scientific approaches did not prevail, during the early period of Japanese IR studies. However, some researchers showed a strong interest in the new approaches. Seki (1959) applied game theory to problems of international politics, only two years after the publication of Morton Kaplan’s System and Process in International Politics and the first issue of Kokusai Seiji . Seki (1969) and Mushakoji (1972) wrote important books that used game theory and computer simulation. Anatol Rapoport’s Strategy and Conscience was translated by Yoshikazu Sakamoto, Hiroharu Seki, and Yoshimasa Yuasa in 1972. Importantly, these scholars were not marginal figures in the IR studies community at the time. Seki and Sakamoto, who were professors at the University of Tokyo, and Mushakoji, who was a professor at Sophia University, were distinguished scholars from the liberal camp. They co-founded the Peace Studies Association of Japan in 1973. As most researchers favored liberal thought, Sakamoto, Mushakoji, and Seki were the most influential IR scholars of the day.

Scientific approaches also attracted researchers from the conservative camp. Among these, Shinkichi Eto, a professor at the College of Arts and Sciences at the University of Tokyo, played a significant role. Although Eto was an Asian history specialist who focused on international perspectives, he encouraged many of his students to learn scientific approaches that he had witnessed during his stay at Columbia University in the early 1960s. As he remembered:

The development of IR studies in North America in the 1950s and 1960s was stunning. … In this underdeveloped field [IR studies], researchers who were trained as biologists, economists, and statisticians were bravely joining … I was impatient to take the cutting edge of IR studies back to Japan. … After returning to Japan, I encouraged, with all my might, young researchers to acquire these new approaches. (Inoguchi 1970, iii–iv)

During the 1970s and 1980s, Eto’s students (and other researchers that he had influenced) presented a variety of studies based on mathematical, statistical, and computational techniques. Content analyses of foreign policy in East Asian countries were published (e.g., Inoguchi 1970; Okabe 1971); econometric analyses of Japan’s foreign policy were conducted (e.g., Inoguchi and Miyatake 1979); a computational model of the PRC’s decision-making process appeared (e.g., Tanaka 1983); stochastic and differential (difference) equation models of war were developed (e.g., Yamamoto 1976, 1984; Yakushiji 1984); and a mathematical model that clarified the relationship between interdependence and conflict was advanced (e.g., Yamakage 1982).

In the early 1990s, a younger generation of Eto’s lineage and other researchers who had studied in the United States developed models that addressed the topics occupying the American IR studies community at the time, including evolutionary game approaches, two-level games, and multilateral economic cooperation between countries. Their research was published in English and was recognized outside Japan (e.g., Kondo 1990; Iida 1993; Suzuki 1994). Meanwhile, Yamamoto and Tanaka (1992) were eager to instill scientific approaches into the IR studies community in Japan. As Tanaka described:

IR studies in Japan have seldom employed “quantitative [and mathematical]” approaches. … We do not consider that “quantitative [and mathematical] methods only lead us to the truth. However, “quantitative [and mathematical]” approaches are exceedingly powerful tools for analysis. … We would be grateful if this book helps, if any, Japan’s studies on war and the international system develop further. (Yamamoto and Tanaka 1992, 263)

Despite these scholars’ efforts, the development of scientific approaches in Japanese IR studies ultimately stagnated, as can be seen from the changing number of articles using scientific and behavioral approaches that were published in theory- and methodology-themed issues of Kokusai Seiji.10 Yoshikawa et al. (1959), Kokusai Seijigaku no Taikei (Studies on International Politics), included only one article that used these techniques (i.e., Seki’s game theory models) out of six papers on the theme.11 In Miyazato et al. (1970), Kokusai Seiji no Riron to Hoho (International Politics: Theories and Methods), five out of six articles used such methods, including gaming methods. The number of articles began to decrease in the 1980s. Yamamoto et al. (1983), Kokusai Seiji no Riron to Jissho (Theory and Method in International Relations), included two such articles out of a total of eight. When Tanaka et al. (2000) presented Kokusai Seiji Riron no Sai Kochiku (Reconstructing International Relations Theory), only one of the eleven papers took this approach. Since Kokusai Seiji reflects the mindset of Japanese IR researchers, these changing numbers indicate that many researchers were gradually losing interest in scientific approaches during the 1980s.

Three reasons for this change can be identified. First, changes in Japanese society were influencing researchers’ research motives. Traditionally, in Japanese society, basic education has been widely available and the public has been aware of social issues. There is high demand for books and articles on politics that reflect people’s interests in this society. As a result, the audience for Japanese IR research is not limited to academics. Academic discourses are sometimes difficult to separate from social debates. In fact, the articles that led to the famous debate between realism and liberalism in IR studies in the 1960s, described in the second section, were published in magazines intended for the public (Sakamoto 1959; Kosaka 1963; Yamamoto 2011, 263–265). On this societal basis, Japan was moving into an unprecedented economic boom that culminated in the late 1980s. As the economic friction between Japan and the United States during the 1980s illustrates, the Japanese people, as well as those in the rest of the world, thought that Japan’s economy would soon overtake that of the United States (Vogel 1979). Consequently, Japanese society in the 1980s was filled with a sense of self-sufficiency, and academia, particularly the social sciences, was no exception. The combination of a highly educated society and economic prosperity prompted researchers to look inward. Scholars who wrote books and articles for the public, which were usually written in a qualitative style, were highly valued, both socially and financially. Although competing with researchers worldwide using common tools, such as mathematics and statistics, was not entirely unattractive, the recognition their research could gain inside Japan sufficed for many researchers.

Second, the fact that historical approaches tended to dominate IR studies in Japan influenced this development. A preference for history calls for rigorous empirical analysis in the present research. Although historical studies cannot guarantee to provide predictions of the future or generalized policy implications, they excel at providing strict interpretations of individual events that occurred in the past, by relying on empirical evidence. At the same time, the generalized arguments generated by formal models are often deduced and may have no empirical foundation. Even if data are applied to these models, the estimates are often rough. The gap between the expectations of Japanese researchers, who were familiar with historical studies, and the state of scientific approaches at the time, alienated scholars from these techniques.

Finally, between the late 1970s and the early 1990s, American IR researchers likewise showed less interest in scientific approaches. In the 1970s and 1980s, their major works of scholarship involved qualitative “theory,” such as Rosenau’s linkage politics, Nye and Keohane’s transnational and interdependence theory, Waltz’s structural realism, Krasner’s international regimes, and Modelski’s hegemonic stability theory.12 In the 1990s, although constructivism was not as popular in Japan as in the United States, Wendt’s argument also affected some Japanese researchers. Axelrod’s computational simulation of the prisoner’s dilemma certainly influenced IR studies in the 1980s. However, researchers in other social science fields, such as psychology, evolutionary game theory, economics, and sociology, seemed to respond more enthusiastically to his experiments. Thus, research trends in the United States affected Japanese researchers, reducing their interest in scientific approaches in the 1980s and 1990s.

The combination of these three factors induced scholars who had once taken the initiative in advancing scientific approaches to embark on studies that were either generalized but qualitative arguments or area studies. For example, Inoguchi (e.g., 1982, 1988) published a large amount of qualitative research on topics such as Japanese diplomacy, the Japanese political economy, and the relationship between Japan and the international system. Tanaka (e.g., 1996, 2000) advanced his own arguments about the world system and Japanese diplomacy. Meanwhile, Yamakage (e.g., 1991, 1997) published works that investigated the regional system in East Asia, focusing on ASEAN. One symbolic fact was that JAIR renamed a section called Suryo Seiji (Quantitative and Mathematical Politics) Riron to Hoho (Theory and Methods) in 1998. Previously, JAIR had been worried that too few members were applying to present papers for that section. By using words that welcomed a broader range of approaches, JAIR expected more members to join the section.

In the 2000s and 2010s, scientific approaches seem resurgent. Obviously, the reverse course traced by current Japanese society (i.e., globalization and Japan’s relative decline) and the trend in American IR studies illustrated by Lake’s argument have had an effect. In Kokusai Seiji, the number of papers using scientific approaches has increased again. Suzuki et al. (2009) have included four articles that used scientific methods in their themed issue, out of a total of seven on the theme. Another issue has focused on rational choice modeling (Iida et al. 2015). Alongside journal articles that use econometrics, game theory, and computational modeling (e.g., Tago 2005; Kurizaki 2007; Yamamoto 2015), books that employ these approaches are increasingly being published in English (e.g., Suzuki and Okada 2017; Tadokoro, Egashira, and Yamamoto 2018). Given this situation, together with normative approaches and Asian studies, scientific approaches have become more promising in Japanese IR studies.

Post-World War II Japan’s peace-related thought (Heiwa Shiso ) has affected the normative argument advanced by both realists and liberals in Japan. Although scholars may themselves have recognized this fact, they have not considered it necessary to explain the extent to which socially ingrained ideas about peace have informed their discourses. This silence is partly responsible for the fact that Japan’s normative argument is not regarded as distinct from those of the other countries. Becoming more explicit about the relationship between the two will change the situation, showcasing Japan’s normative approaches within the global IR community.

Japanese Asian studies researchers have been convinced of their own originality. However, their confidence has led them to underestimate the importance of sharing their research with colleagues outside Japan. As the third section of this paper describes, the situation is now changing, allowing Japan’s Asia specialists to be more regularly consulted by the world research community. Finally, despite various late twentieth century initiatives, scientific approaches to IR have remained dormant in Japan until recently. However, the present situation surrounding Japanese society and IR community in Japan has prompted researchers to change their research style.

By practicing the above prescription for defining their normative argument, and continuing the direction currently observed in Asian studies and scientific approaches, Japan’s IR studies are expected to gain further global recognition in all three areas.