ABSTRACT
The economic literature on migration has grown rapidly over the last decades. Although the literature covers a wide range of different topics which are all related to migration, it has three distinct characteristics. First, it focuses almost entirely on labor migration, and other types of migrants (e.g. refugees) are typically ignored. Second, it contains a well-known, but often unexpressed, division between internal migration (migration within countries) and international migration (King and Skeldon 2010). Third, it emphasizes on the determinants of migration rather than their consequences (Greenwood 1985). However, because the causes of migration and its consequences are closely related, the same theories can be used to explain both international and internal migration. There are numerous theories that explain migration. Because motives to migrate are com-
plex, these different theories should be viewed as complementary rather than contradictory. In this chapter we explore six common theories, discuss their policy implications, and their empirical support. We end the chapter by reflecting on a commonly ignored issue in empirical surveys, i.e., we discuss the importance of accounting for different time horizons when evaluating causes and effects of migration empirically. This discussion highlights the importance of viewing migration theories as complementary rather than contradictory. Despite the existence of numerous labor migration theories, these can effectively be classified
into either of the two following categories: (1) theories of the initiating causes of migration and (2) theories of the self-perpetuating causes of migration (Massey et al. 1993). At least three theories can be placed in the first category; neoclassical theory, the new economics of labor migration theory and dual/segmented labor market theory. And, at least three theories can be placed in the second category; network theory, cumulative causation theory, and institutional theory. In neoclassical theory, individuals will migrate when the expected income is higher at the
destination than at their current residence. The New Economics of Labor Migration (NELM) theory, on the other hand, stresses the importance of the household as the decision maker rather than the individual, and hypothesizes that individuals are not indifferent to risk (i.e. they are risk-averse). Therefore, population movements can take place even if there are no perceived differences in the expected income between regions, which are not possible in neoclassical
models. Dual Labor Market Theory studies migration at a higher level of aggregation than the former theories, and emphasizes basic structural characteristics (e.g. the wage formation process) in the economy, which creates a demand for immigrant labor. The Dual Labor Market theory was mainly developed to explain some empirical observations, typically unexplained by other models. For example, the income distribution in many economies is not entirely explained by the fact that different individuals have different talents and levels of education (Cain 1976). The second category of theories involves explanations of the self-perpetuating mechanisms of
migration. Simply put, these theories explain how current migration flows can cause future population movements. Network theory, for instance, belongs to this category as it acknowledges the fact that migrants provide friends and relatives back home with support and information about the destination area. Connections between migrants and relatives back home therefore induce more migration. Cumulative Causation theory explains several self-perpetuating forces of migration, for instance
the effects of migration on the income distribution and agricultural production in origin areas. Institutional theory focuses on the necessary institutions, which assist both legal and illegal (typically international) migration. One example relates to the fact that many countries restrict immigration, which generates a need for services that can assist the “underground migrants.” Therefore, former migration leads to more migration because of the formation of different underground activities such as smuggling of migrants and providing the migrants with false documents (visas, passports, etc.). In the remainder of the chapter we discuss, more extensively, each of the mentioned theories
one by one. In the second section we discuss theories of the initiating causes of migration. In the third section, we discuss the self-perpetuating forces of migration. In the fourth section we elaborate on empirical issues and exemplify by drawing from our own work on migrant remittances.
