The human condition is analog not digital. As in the non-human animal world, human sexuality is found along a spectrum of relationships. From a biological perspective and without scientific intervention, procreation in humans requires an individual male and an individual female.
Before considering the question of gay marriage, a more fundamental question should be considered: Why marriage at all?
In the United States, marriage is a tri-party legal agreement. The first two parties, husband and wife, are obvious. The third party is the state/community that acknowledges a marriage. Male and female couples petition the state –and more generally, their community– to recognize their marriage. If it was just a simple relationship amongst consenting adults, the community would have no need –and more importantly no business– acknowledging the relationship.
However, marriage is a relationship that imposes responsibilities on the community and that’s why the state is involved in its recognition and definition; as in detailing that only two (not more) individuals of the opposite sex will be recognized in a marriage. Married couples get legal tax and inheritance status. Male-female couples asking the state to recognize their marriage are also asking the state to address the care of their biological children if the couples are incapable of doing so.
What does the community get in return for consideration of this ‘special’ status? It is rejuvenated –by the only relationship that can procreate: a male-female relationship– and benefits from responsibly raised children in a marriage. Because of the corrosive effects to the community of infidelity, the community acknowledges only monogamous marriages. This shared responsibility amongst all the parties (husband, wife, community) is the limited government rationale for marriage as a legal construct.
Gay couples asking the community to recognize their relationships have a responsibility to address the question: ‘In return for the community’s recognition, what will you do for the state that justifies more government?’. They may counter that some gay couples have children and that their care benefits the community. But these children are not, and can not be, the offspring of a gay marriage. They are the shared responsibility of the biological parents and the state. The existing legal constructs are sufficient to address the children’s and community’s interests.
The state/community will be a party to any marriage and therefore has every right to say what marriages it will recognize. The gay couples seeking recognition must make their case for community involvement in their relationship when the sine qua non condition of biological procreation does not exist and there are sufficient laws to deal with any children in a gay relationship. Until the argument for an expansion of government is made, the basic principle of limited government, the minimal amount of laws our society needs to function, should prevail.
- Update 12/11/2012: Scientists May Have Finally Unlocked Puzzle of Why People Are Gay)
- Update: 12/30/2012: State of Kansas wants sperm donor found on Craigslist to pay for daughter born to lesbian couple
- Update 2/5/2013: The Washington State Court of Appeals affirmed the argument of marriage being between a male and female in Singer v. Hara: see HeadNote  along with its detail.
 Marriage -- Nature of Marriage -- Public Policy -- Same-sex Marriages. The legislative purpose behind RCW 26.04, which authorizes marriage only between two persons of different sex, is to give effect to the public policy of marriage being an appropriate and desirable forum for procreation and rearing of children. The prohibition of same-sex marriages results from the impossibility of procreation.
- Update 2/9/2013: Florida judge approves birth certificate listing three parents)
- Update 6/29/2014: The Brave New World of Three-Parent I.V.F.
- Update 11/7/2014: 6th Circuit Echoes Porkopolis' Arguments on Rationale for State of Ohio Defining Marriage
- Update 04/26/2015: What is Marriage? in Harvard Journal of Law and Public Policy, Vol 34, No. 1, pp 245-287