The theories of migration are:
- The Neoclassical theory bases its arguments on differential wages. This means that international migration is necessitated by the scarcity of labor in some nations and the surplus of labor in others. The geographical disparity in labor supply and demand acts as the incentive of migration. As labor moves to the scarce nations, capital is supposed to move in the opposite direction so as to counteract the results. According to this theory, people will also move as a result of the high wages that are being offered in a specific country.
- New Economic Theory is another theory and it is mainly based on risk minimization across markets. The individuals, who migrate, according to this theory, are usually risk-averse about any market failures that might occur in their mother nations. They try to minimize the risk that would result from a market failure in the futures market, capital markets, and credit markets in the countries that they live in. Most people also migrate to insure themselves against retirement and unemployment in their current economy. Others migrate as a full household so as to benefit themselves from the wage differentials in different geographical places. The other factor that increases migration is the rise in relative deprivation among households.
- Segmented labor Market theory is based on demand in differential labor markets. In a dual market, there exists the primary segment and the second segment. The primary one has capital-intensive production methods while the second segment has the main characteristic being the labor-intensive production methods. A higher income is offered to those who are in the primary segment and are skilled to do the job. This ensures that they have better social conditions than the less paid people. Because of the low birth rates in developed countries, there is scarcity in the number of young people who are willing to take up the bottom jobs for the experience. Therefore, people migrate from the developing countries to fill up such positions and hence giving them the social security which they are in dire need of.
- The historical-structural theory is based on the expansion of the world capitalist production systems. According to this theory, the political and economic powers are not equal across all nations and this allows the unequal distribution of resources. This inequality between the developed and the developing countries makes the developing countries to be disadvantaged in their access to resources and they are consequently forced to rely on the developed countries. According to Massey, migration has resulted due to the imbalance in the terms of trade between the developing and the developed countries. Under this theory, the individuals who migrate do not do so under the free will but are instead put under pressure by structural forces which deprive them of their traditional livelihoods.
- The Social Capital Theory has its argument based on the cumulative causation and the social networks that are formed. Migration is necessitated by the existing migrant networks and the supporting institutions. Once some individuals have migrated, the movement of others who are close to them is made easier because of the already established social networks in the new place. The settlement of the latter immigrants, therefore, takes less time and effort.
To synthesize all these theories, the major cause of migration in the modern-day world then is the rational thinking of individuals and corporates. The migration pattern in the Asian and Pacific region has been caused mainly by the surplus in labor supply in Asian countries. There is also the existence of communication and network links to the Asian countries that have facilitated migration.
This was as a result of the heavy investment in these countries where there is capital scarcity and labor surplus. The presence of military troops in these Asian countries also increased the number of links that were being built. The Vietnam War resulted in a large number of refugees escaping from their country which was facilitated by the open entrance by the United States, Canada, and Australia.
Because of the oil in the countries, the construction of the extraction and transportation networks also served to increase the number of people who migrated. Most Asians will also migrate to places where they have an already existing social network which helps them to adjust easily to such new places. Another great boost to the Asian-Pacific migration is the existence of numerous facilitators like recruiters, travel agents, and immigration officials.