As for the purpose of nations, let me quote John Locke's Second Treatise.
Locke states as one of the key purposes of nations:
"There wants an established, settled, known law, received and allowed by common consent to be the standard of right and wrong, and the common measure to decide all controversies between them: for though the law of nature be plain and intelligible to all rational creatures; yet men being biased by their interest, as well as ignorant for want of study of it, are not apt to allow of it as a law binding to them in the application of it to their particular cases."
So the purpose of nations is to enforce the natural laws. So what are these natural laws?
"The state of nature has a law of nature to govern it, which obliges every one: and reason, which is that law, teaches all mankind, who will but consult it, that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions:"
Notice that one of these laws is the protection of liberties, the liberty to speak one's mind among them.