I believe that marriage is between a man and woman. It has been for all of recorded history and I think this is a temporary aberration that will dissipate. I think that it is just fundamentally goes against everything we know.
In short, Gingrich attempts to overcome homosexual marriage on two grounds: intuition and history. We'll leave aside the former, since it would seem that Gingrich is woefully out of touch with presently goes against everything his culture knows. What is left is the question of history. As the linked article shows, many are content only to go so far back as Gingrich's own checked marital past and dismiss his argument at that. The problem with this, however, is that such a shallow engagement doesn't address what ought to be the startling truth of Gingrich's historical assertion, at least on the surface. Same-sex marriage is a historical novelty, such that even in cultures where homosexual behaviors were tolerated and even idealized the idea of a homosexual marriage was unthinkable.
The real problem with Gingrich's argument is not his personal disqualification on the basis of adultery and serial monogamy or even an incorrect assumption that same-sex marriage has some kind of historical precedent. The quandary arises when anyone attempts to apply Gingrich's historical canon to marriage more generally. For example, a majority of societies historically have permitted if not widely practiced polygamy, and the practice has been historically permitted in four of the five major world religions: Judaism, Islam, Hinduism, and Buddhism. Numerous contemporary cultures continue the practice, including sub-cultures within the United States itself. By the historical logic of Gingrich, polygamy should be permissible under US law.
We might apply the same historical logic to the proper age of marriage. In ancient Greece, the ideal age for a woman to be married was her early teens. This expectation carried into that other archetypal Western culture, and is enshrined in Roman law which permits marriage before the age of twelve provided the consummation does not occur until twelve years of age. The Corpus Juris Civilis even includes this curious law which addresses what happens to a wife who cheats on her husband prior to that age of consummation: "Where a girl, less than twelve years old...commits adultery...she cannot be accused of adultery by her husband, for the reason that she committed it before reaching the marriageable age." Medieval law proves more telling, in that Gratian allows that a girl may consent to be married as young as seven. In Elizabethan England, a girl could consent to marriage at twelve and could not revoke that consent after fourteen. By Gingrich's historical logic, I ought to be able to marry a girl on the very cusp of pubescence--though it is perhaps up for debate what legal recourse I have if my eleven year old wife elects to have sex with another man.
The implications of applying such a historical logic for marital practices raises countless more problems. Should we allow for arranged marriages that do not have the consent of those involved or perhaps have a coerced consent? Should women have the right to file for divorce? Should we go back to the borderline chattle slavery system of marriage in classical Athens? Or to the guardianship system of Rome? Will we go back to a system of marriage by capture (in which case, can someone find me Jena Malone's address)? Which parts of recorded history do you suppose Gingrich is interested in endorsing?
There is no doubt that I do not think people of the same sex ought to be having intercourse, cohabitating, raising children, or getting married. My arguments, however, are moral and religious. Attempting to appeal to history as an arbiter in the discussion of the legal permissibility of same-sex marriage raises more problems than it solves, in large part because the history of human dependence on prolific procreation--only recently escaped--is an appeal to a dead priority. More obviously, it is an appeal to the human race which has proved more than willing to shape legal and cultural norms to its whims for the entirety of its history. That means that if marrying multiple young girls through rape was expedient and enjoyable (and why wouldn't it be), then it was culturally and legally enshrined until countervailing ideological (or more commonly military) forces dislodged it. Unfortunately, much like advocates of the amusingly oxymoronic "civil Sabbath" in the nineteenth century, opponents to same-sex marriage are forced to find a secular logic for their fundamentally religious opposition the practice because admitting their exclusively religious motivation would disqualify their position from consideration. Of course, if Gingrich were to admit this it might represent a frightening step down the road toward incurable Ron Paul.