Government promotes marriage to make men and women responsible to each other and to any children they might have. Promoting marital norms serves these same ends. The norms of monogamy and sexual exclusivity encourage childbearing within a context that makes it most likely that children will be raised by their mother and father. These norms also help to ensure shared responsibility and commitment between spouses, provide sufficient attention from both a mother and a father to their children, and avoid the sexual and kinship jealousy that might otherwise be present.
There are five reasons that laws exist in society. The Harm Principle states that laws exist in part to protect people from violence and abuse. These laws make murder and theft illegal. The Parental Principle states that laws also exist to protect people from themselves. For instance, a law states that all children must go to school, which most children would not naturally do on their own. The Morality Principle states that another reason for laws is to advocate a sense of morality. Laws against hate speech is an example of this principle. The Donation Principle explains the importance of the government using laws to grant certain services and commodities to society and the individuals within it. An example is the laws related to welfare that grant aid to those who are unable to provide for themselves. Finally, laws are important because they protect the government from harm, as explained by the Statist Principle. Treason is illegal under this principle, which helps to keep the government intact and functioning.
On a break from college in the 70s, I was visiting a church in rural Illinois. There in the literature racks in the back of the church was a lurid pamphlet about the evils of marijuana — all the old reefer madness propaganda about how it caused insanity and murder. I approached the minister and said “You can’t have this in your church. It’s all lies, and the church shouldn’t be about promoting lies.” Fortunately, my dad believed me, and he had the material removed. He didn’t even know how it got there. But without me speaking up, neither he nor the other members of the church had any reason NOT to believe what the pamphlet said. The propaganda machine had been that effective.