The ability to procreate has never been a test for the issuance of marriage licenses.
I've deflected this argument dozens of times, including more than once on this very thread. Let me put it in full context, so that hopefully I won't have to do this again. First of all, please don't muddy the waters with insignificant exceptions to sweeping truths.
Monogamous marriage as the overwhelmingly prevailing norm and structure for families predates all of our state governments. None of the states, including Massachusetts, has ever enacted laws that have redefined marriage as anything but a union of one man and one woman.
It is fair to say every state currently requires of any couple who wish to be married that they be of opposite gender. All I am arguing is that this arrangement makes sense and we should keep it that way.
I make the case for making sense based on what role marriage has played, plays, and will play for the forseeable future in Western (and Eastern for that matter) Civilization. The stability of laws like this across generations is important. To be sure, immoral institutions like slavery that do harm are not honored just because they exist for a long time. We have justly ruled out race as a test for civil marriage, but we have rightly retained the opposite-gender test. And through many many centuries the institution of marriage has been a wonderful boon to our way of life.
The reason the opposite-gender test makes sense is that, over the huge sweep of human space and time, opposite-gender couplings are the telling ones, because their sexual relations produce children. Children born and raised in stable families do fine, by and large. After they grow up, they tend to repeat the process and that is a good thing.
Take away marriage, and you have a downward societal spiral into chaos. Do you agree?
We have established that opposite-gender couplings are the ones of real concern to the common good. True, coupling and marriage have reasons to exist outside of children. There is no fertility test for marriage and noone has advanced any reason that it would be a good idea to have one. Anyway, these extra roles of marriage do not detract from its main purpose of reinforcing a multi-generational pattern of stable families. But at the same time, what net good with respect to the purpose of marriage would be accomplished by redefining it to be the union of any two consenting adults? Practically zero. The children living with same-sex couples are as important individually as any other children, but their existence in tiny numbers does not justify this change that has the potential to roil our culture for decades.