by Josh DeWind

Recent research on relations between migration and development has focused largely on international migration and its impact on economic growth, poverty, and inequality in sending countries. The Social Science Research Council invited Stephen Castles (International Migration Institute, Oxford University) and Gustave Ranis (Economic Growth Center, Yale University) to assess what is known generally about relations between migration and development and what issues ought to orient future research to improve understandings of those relationships. They approached the question from quite different perspectives: that of a sociologist who has specialized in the study of international migration and of an economist with a specialization in development studies. While each sees migration and development as “part of the same process and therefore constantly interactive” – rather than as one predominantly causing the other – their analytic approaches to building theoretical understandings of the process are distinct.

What redefinitions of the conceptual boundaries guiding current research of migration and development are suggested by brining together different perspectives from the fields of migration and development studies?

How do the two field’s theoretical approaches differ and how might each inform and improve the approach and expand understandings offered by the other?

How might interdisciplinary research be designed to take both approaches into account to guide future research and better inform policy makers and practitioners?

Related to these questions, both papers provide useful histories of the different theories of migration and development that have predominated in their separate fields and they build upon current theoretical perspectives to offer relatively inductive and deductive approaches to guide future research. Comparison of their different perspectives suggests that understandings of migration and development could be improved by broadening the scope of research to consider both internal and international migration and to examine economic development in relation to other aspects of social transformation.

Ranis’ approach begins with a the rural-urban, dual economy models of national development, which were proposed by the 18th century physiocrats and 19th century classical school of economics and then amended toward the end of the 20th century by developmental economists. Ranis elaborates these closed economy models by differentiating between productive sectors and labour markets (agricultural and non-agricultural rural sectors; informal services and sub-contracting and formal urban sectors) between which laborers migrate in search of employment to improve their circumstances for work and well-being. This model predicts that, through economic growth, internal migration, and migrants’ inter-sectoral transferring of resources a national economy will eventually evolve into a “one-sector, relatively full employment, neo-classical world” as exemplified by the development processes of Japan, Korea, and Taiwan in the 1960s to 1980s and by contemporary development in China, Vietnam, and Thailand in the present.

To take globalization into account, Ranis opens the closed development model internationally in order to identify from which sectors international migrants depart as unskilled and skilled workers and to analyze the contributions that the resources they transfer back home, particularly remittances, can have on development.

In focusing on the migrants’ transfer of resources between international and national productive sectors Ranis identifies a series of questions for future research that can illuminate not only the impact of migration on national economic growth but also its contribution to reducing poverty and enabling the realization human development and capabilities more broadly. Considering how to address these research questions, Ranis recognizes that “the migration and development nexus truly represents an interdisciplinary and exciting ball of wax which is, however difficult to disentangle by means of an ambitious general equilibrium approach.” He concludes his paper by posing a challenge to future researchers: “How can we manage to embed the economics-focused analysis of migration and development within a broader socio-political framework which recognizes the important interdisciplinary dimensions of the issue?”

If Ranis’ approach is deductive – to elaborate upon a relatively simple economic principles in order to gain insight into admittedly complex causes, processes, and outcomes of both internal and international migration in relation to development – then Castles’ approach moves in an opposite, moreinductive direction to seek synthesis from diverse theories developed in multiple social science disciplines. Whereas Ranis’ approach reflects confidence in the universality of a basic economic model whose elaboration is expected to yield explanatory insights into the complex relations between migration and development, that of Castles reflects his dissatisfaction with the interdisciplinary fragmentation of theory within the field of migration studies and the resulting inability of researchers to persuade policy makers of a relatively simple research finding: that “a higher level of development brings more mobility.”

The narrowness and fragmentation of theory within migration studies that trouble Castles the most derive from disciplinary separations that “disembed” economy from society as if these spheres were not integrated. The antidote, he proposes, is a broad, interdisciplinary, and synthetic approach that would bring together theories of economic development and social change under the rubric of “social transformation.” The methodology to accomplish such a synthesis would be to link various levels of socio-spatial life ranging from the local to the global, thus not only reflecting the micro-to-macro nature of relations between migration and development but also taking advantage of the tendency for disciplines such as geography, anthropology, sociology, politics, and economics to focus on different aspects of social organization. Castles cites a number of recently formulated theoretical approaches within migration studies that he believes can contribute to the more holistic synthesis he seeks, including theories of demographic transition, new economics of labor migration, segmented labor markets, and transnational migration.

Elaborating on economic models to incorporate broader, global social processes, as Ranis proposes, or synthesizing theories of social change in order to connect with models of economic development as Castle proposes, pose rather than resolve the challenges facing migration and development studies. As Castle concludes, “starting from simplicity versus starting from complexity cannot be simply resolved by meeting in the middle.” Rather he suggests, the challenge of bridging disciplinary differences of conceptual and analytic approaches and linking different socio-spatial level of analysis might be accomplished through the design of “a more embracing and comprehensive model that goes across disciplines and at least permits middle range-theories.” Whether or not a unified interdisciplinary theory is in the end feasible, the approaches of both authors suggest that interdisciplinary collaboration between researchers is a necessary in analyzing of issues related to remittances, “brain drain” and “brain gain”, circular migration, diaspora investments that have become central to migration and development research and the elaboration of public policies to enhance the contributions of migration to development.