Brandon Vogt asks Prof. Robert George, Princeton professor and author of "What is Marriage? One Man, One Woman: A Defense" three questions about marriage. Here is one of them:
OSV: Some people wonder why the government even concerns itself with marriage. Why does it regulate this type of relationship?
George: Marriage is critical to the success of any society because it is the way that mothers and fathers are united to each other in a relationship uniquely apt for the project of child rearing. Now, obviously, law and the state have a profound interest in successful child rearing. Every other social good depends on that.
So, although the state did not invent marriage — marriage, properly understood, is a pre-political institution — the state rightly and necessarily recognizes marriages, distinguishes marital from nonmarital forms of relationships, and supports, regulates and promotes marriage in the hope of sustaining a vibrant marriage culture.
This explains why, historically and across cultures, governments have formally recognized and regulated marriages, even though they have not done that for ordinary friendships, relationships among siblings or purely religious sacraments and ceremonies, such as baptisms and bar mitzvahs. (OSV)