Your question could be phrased as: &quot;Why should we consider our own welfare over that of others?&quot;  Part of the answer to that is that for a thing to survive, it must discriminate in its own favor, especially because other things will also be doing so.  The other part is that <i>survival, and even preference, are legitimate ends, and need no justification.</i><p>That&#x27;s not really an answer <i>to</i> you; rather, it seeks to provide rhetorical relief for the native pondering whether he is morally obligated to throw open his borders.  He or she is not.  Their survival, and even comfort, are legitimate goods.  They may calculate utility differently than their would-be neighbors, and <i>that&#x27;s OK.</i>  Vote, let them vote, converse; but don&#x27;t attempt to dialectically back them into a corner.  Friends don&#x27;t criticize each others&#x27; utility functions.