Conservatives Say Marriage Has Always Been between a Man and a Woman. They’re Wrong.

What is a marriage? Conservatives argue that it is one man and one woman in a permanent union for the purpose of raising children. This arrangement, they say, should receive special consideration by the Supreme Court because of its long-standing place in society.

They’re wrong.

Marriage is a constantly changing social institution that adapts to social and economic conditions. And when those conditions change, marriage changes.

Our modern view of marriage — one that has generally predominated in Western societies over the past 200 years — is the outlier. Historically, marriage has been about finding good in-laws and securing economic advantage. And marrying for love is a thoroughly modern invention.

While many social and economic factors have changed marriage, perhaps none has done more than the shift in the economic status of women. When women had few possibilities for remunerative careers — or any career at all — marriage was more about securing financial security for herself and her children. In situations of poverty, marrying for love is not only a luxury, it is nearly suicidal.

Marriage is a constantly changing social institution that adapts to social and economic conditions.

In some times and places, a “marriage” defined the roles of each participant, regardless of sex. This helps partially explain why same-sex marriage has been historically rare. In ancient Rome, for example, Emperor Nero married his boy slave Sporus and treated him like a woman. According to marriage historian Stephanie Coontz, most Romans largely found same-sex marriage repugnant because “no real man would ever agree to play the subordinate role demanded of a Roman wife.”

Similarly, some West African societies have allowed women to have “female husbands” — in which any subsequent children of the “female wife” were regarded as descendants and heirs of the “female husband.” And some Native American societies made a sharp distinction between “woman’s work” and “man’s work,” allowing same-sex marriages where two gender roles were represented. In fact, according to Coontz, such marriages would not have even been considered “homosexual.”

Nevertheless, same-sex marriages have been historically rare, particularly in post-Medieval Western societies. It is somewhat perverse, however, for conservatives to argue that the general lack of same-sex marriages over “millennia,” to use a word from Justice Anthony Kennedy’s question during oral arguments, somehow underscores the value and necessity of “traditional marriage.” For “millennia,” a church/state alliance marginalized and oppressed homosexuals via the law, including many laws, such as bans on sodomy, which the Supreme Court has struck down.

It’s odd to use a history of oppression and marginalization to argue for further oppression and marginalization. Similar arguments were made against women’s rights in the 19th century. In 1873, the Supreme Court ruled that the state of Illinois could prevent a woman from being admitted to the bar because “the natural and proper timidity and delicacy which belongs to the female sex” was “firmly fixed…in the founders of the common law.”

Marriage has seen so many forms that it is almost difficult to give a universal definition of the term. Nevertheless, the lawyer arguing for “traditional marriage” in the Supreme Court felt confident to say “the marriage institution…developed to serve purposes that, by their nature, arise from biology.” Yet some cultures, such as Japan, historically made few distinctions between children of wives and children of concubines, and one emperor was actually the child of a concubine.

Nevertheless, conservatives are right that the concept of marriage has drastically changed in a relatively short time. That shift has paralleled the equally drastic changes in the economic status of women, the idea of gender roles and the acceptance of homosexual conduct. Thankfully, it is long past the time when conservatives can reinstate their Ozzie and Harriet idea of marriage and put our Modern Family concepts back in the box.

Growing wealth and expanding women’s economic possibilities have made marrying for love not only a possibility, but an expectation. Marriage is now about two people publicly expressing their love and commitment. Child rearing is important but no longer definitional, nor is securing political alliances or ending inter-tribal warfare.

Social institutions evolve faster than recalcitrant and reactionary governments. People are now FWB (Friends With Benefits) rather than “going steady,” and they’re “Facebook official” rather than “being pinned.” When social institutions evolve, those who are stuck in the past often prefer to use the coercive power of government to keep things “the way they should be” than to go with the flow. That “flow” has already changed the institution of marriage, and the Supreme Court should go with it.

Trevor Burrus is a research fellow at the Cato Institute’s Center for Constitutional Studies.