In the European Union, the Schengen Agreement has resulted in the relaxation of border controls among participating European countries.
It is easier for Europeans to move around, but it has also resulted in large imbalances.
There are now entire areas filled with people of different cultures and habits from the locals'. The problem of unchecked flow of refugees often arises as well.
There are social, legal and civil implications that have caused difficulties to EU citizens.
Hence, Deputy Prime Minister Tharman Shanmugaratnam is right to say that there must be limits to the movement of people ('Wrong' to have total free flow of people: Tharman; July 23).
Uncontrolled immigration might put a strain on our infrastructure and could change our culture.
Singaporeans may get upset, as the range of job opportunities changes and they feel they are not the priority.
However, there is also a positive side. Immigrants are attracted to growing regions and they increase the supply and demand in the economy, thereby expanding employment opportunities.
They take on lower-wage jobs and jobs that Singaporeans avoid. This eases the labour shortage here.
Immigrants who become citizens or permanent residents grow the tax base and tax revenue for Singapore.
In an ideal world, Singapore would be able to sustain everyone who wants to come here.
But we live in an imperfect world where there is a limited amount of resources.
We should advocate smart, sound and beneficial immigration.
We need to fix the system so that we do not have the gates wide open, but neither do we shut talented people out.