There is a social psychological hypothesis that was tested in extensive research a long time ago.  The hypothesis is called the Contact Hypothesis, and it was proposed as a way to reduce intergroup prejudice and conflict.  The general idea is based on the intuitive notion that if you just get to know someone, you will like him more, or at least hate him less. The reality is that contact only works favorably under social conditions that are in fact wildly difficult to achieve in the real world. Contact can lead to greater harmony if the following conditions are met: the groups or people are of equal status, they have shared goals, intergroup cooperation is required, people of the two groups have to actually interact, and there is recognition of common laws and authority.  When those conditions hold, people from different groups start to shed their preconceptions and prejudices.