I think that the same logic that is applied to the increase in rights for people of color and women in the right to vote is used by many in the defense of same- sex marriages. Many advocates of same- sex marriage cite the United States' history in banning interracial marriage, reflecting than an ethical understanding and evolution enabled social norms to understand that interracial marriage did not need to be banned. The same ethical focus is used by many to expand the definition of marriage to be more inclusive. It is the same ethical perspective that is used in justifying the advance of same- sex marriage. The ethical perspective here is one of equality for more people, something that the President himself cited in his "evolution" towards the subject of gay marriage.
I think that one particular issue might need to be raised here. Certainly, one can argue that an ethical consideration was in effect in the expansion of rights for people of color and women in American political history. This same consideration has been cited in the support of same- sex marriage. Yet, I think that a strong case can be offered to suggest that it was not ethical understanding that played a role in any of these policy shifts. Rather, it was political pressure brought to bear on the Status Quo to react the way it did. The rationale for this was that such ethical considerations had been raised prior to the passage of each separate political inclusion and had been rejected. People of color had been advocating for greater political inclusion for some time and had been rebuffed. Women had been advocating for their own political voice in the system for some time and had also been rejected. The issue of same- sex marriage as being included in the definition of marriage has been around for some time. In each of these cases, the ethical consideration of equality had been invoked. Yet, there had been rejection because the social forces had deemed these ethical considerations and not meritorious of change. I think that this might suggest that it was political pressure or social pressure that initiated policy change and not necessarily ethical considerations.