04/10/2013 01:45 pm ET Updated Jun 10, 2013

Redefine Marriage? Absolutely.

About 2,000 years ago, a group of radicals called rabbis sought to redefine marriage. "Traditional marriage" at the time looked something like this:

Two families of similar socio-economic status sought to preserve their wealth by arranging a marriage between their children. They negotiated a deal with conditions that included a dowry as well as obligations on the woman to provide for her husband's home. In fact, in much of the literature of the time, she was simply referred to as his bayit -- his house -- the absolute homemaker.

Sometime after the betrothal, she was marched under a wedding canopy from her father's house safely into her new husband's home (or more likely to her father-in-law's house as the husband was probably only an adolescent and not yet independent).

If she failed to please him, the husband could hand his wife a bill of divorce. (She could not do so if the reverse was true.) This could potentially leave the girl -- and she was most likely still a girl -- impoverished.

Because of the risk of women being left destitute, the rabbis intervened and created a document called a ketubah. This document became mandatory for all weddings. It was basically a prenuptial agreement that a wedding was not a casual affair but was rooted in a time and place with witnesses. The groom had an obligation to his wife, and she had rights as well. And if he wanted to divorce her, he was required to pay her a certain sum of money in order to protect her from poverty. A court could enforce the payment of her ketubah.

The ketubah back then still defined women according to their status (with less of a payment if the woman was a divorcee or widow) that today we would find offensive. But make no mistake: by creating the first prenuptial agreement and advocating for women's rights, the ketubah redefined marriage.

A different revolutionary move happened later in the Middle Ages. Church law and Jewish law began to forbid men from having more than one wife. In the history of Judaism, this prohibition happened definitively in the 10th century by Rabbi Gershon. This, too, eventually became the norm.

An equally important effort is being made today to allow same-sex marriage. As I argue in my book, ""A Man's Responsibility: A Jewish Guide to Being a Son, A Partner in Marriage, a Father, and a Community Leader" (Jewish Lights Publishing, 2008), while some say same-sex marriage flies in the face of tradition (and it absolutely contradicts certain passages of Scripture and a long legal legacy), we should ask ourselves what tradition looks like. How selective do we want to be when we refer to "traditional" marriage? Do we include arranged marriages for children? Polygamy? Doesn't tradition also include the revolutions that took place as we grew in knowledge and wisdom?

Scripture rejects the act of sex between those of the same gender. But we have learned a great deal since then and must always learn anew from our Scripture and the world around us with the minds God has given us. Just as our rituals are hallowed by time, we must be careful because prejudice and violence are also very old as well. And shouldn't we keep in mind Scripture also says we are all made in the image of God (Genesis 1:27)?

We need to redefine marriage to include gay and lesbian couples with the same vigor that the rabbis introduced the ketubah and legislators banned polygamy. We should see same-sex marriage as the latest revolution in the creation of unions sanctified by God. It is a repudiation of prejudice and oppression and an affirmation of human rights. It brings the support of community into the private lives of two people who love each other. It also affirms that we reinvent traditional practices as human beings struggle to morally progress and evolve.

If only we were as brave as the rabbis were back then.