Recently I was reading some commentary on same-sex marriage and was intrigued by some of the comments made in defense of it (look in the comments in the link). The comments started out, "[Marriage] is neither an essential unit of civilization nor is its ‘main purpose’ to have children." So if this is the case then there must be another purpose to it, which is the "main purpose". Later on someone else made the statement, "Marriage, in this country at least, is a legally recognized union of two people committing to each other, to live together as a couple: shared home, shared hopes, shared finances, same aspirations, dreams, and goals. It is a commitment to be there for the other, through thick and thin, good and bad." And still later we have, "Anytime people join together, combine efforts of survival and work for common goals, they are healthier and more productive. They save more, spend more and accomplish more. It IS in society’s best interest that people pair up. Other than that, marriage holds no value to any community outside the value to the persons involved."
So let us look at these arguments in defense of same-sex marriage and find out what their logical argument is in defense of same-sex marriage. While others may have other arguments in defense of same-sex marriage these three statements are a fairly good summary of the basis of all arguments for same-sex marriage. While the argument for equal protection and freedom to act for one's self may require a separate analysis, those two arguments ultimately rest on these arguments.
First they make the argument that children are not the ‘main purpose’ of marriage. So if having children are not the main purpose then what is? The answer is very simply, marriage is a relation between two people, a relation where each partner cares for and has the interest of the other at heart. Marriage as such can also be considered an advantageous socioeconomic relation in which two people may enter to achieve a desirable economic and social outcome. Considering this definition of marriage it seems like a workable definition because it has suitable "good" and "desirable" qualities relevant to our culture such as: personal thrift and industry, compassion and selflessness, altruism and fiscal, social and moral responsibility. With this impressive list of desirable qualities it is hard to argue against marriage as an institution and as one person concluded "It IS in society’s best interest that people pair up." For the sake of this current inquiry I will call these feelings of commitment and selfless altruism philo. (While these things are definitely related to the Greek notion of philia they may not be the same thing but for this present argument it will be easier to refer to these things as philo).
The natural conclusion is that if any two people have these qualities, or philo, in their relationship then surely it would be a travesty and a miscarriage of justice to not allow them the right to express and live up to their commitment. Because philo is such a desirable thing the obvious conclusion that those presenting this argument wish us to draw is that we should not deny any two people the right to express their philo.
Herein lies the logical fallacies of their argument. First they claim that children, and having children are not the ‘main purpose’ of marriage. This immediately leads to the question, then what is? To which they respond, "Philo". Thus their argument is that the ‘main purpose’ of marriage is so that two people can have and express philo. This logical fallacy is known as the fallacy of division. While philo is (or at lead should be) a component of marriage, having philo is not marriage. If this were true then anyone could marry anyone and thus there is no need to even have the definition of "marriage". This conclusion is a classic case of a suppressed correlative in which the definition is modified to the point that it no longer useful. Thus if we define marriage as consisting solely of a basis of philo between two people then we run into the problem of not having an "edge" or "end" to the definition of marriage, and marriage is of no effect and useless.
The problem here is not that philo should not be a component of marriage, but that it is not the only component of marriage. One major distinction that separates relations of philo, or friendship, from the marriage relation is the ability to conceive, have and raise children. Thus making children the essential difference between relations of philo and relations of marriage. It would seem that having children really is the ‘main purpose’ of marriage.
An instant objection that would be raised by proponents of same-sex marriage is that homosexual couples, through modern techniques (or even not so modern techniques) or adoption, can have and raise children, thus making them a "family" where the "parents" should have the right to be married. The problem here lies not in the relative merits and/or abilities of the pair in raising the children, but again in a logical fallacy, resulting from an incomplete definition.
Because a lot of the groundwork has already been laid I will not reestablish it for this argument. The logical fallacy here is one of equivocation. If we look at the original definitions of what constitutes marriage given above, we see that they include or are equated with philo and at no point is eros, or romantic love (meaning specifically, sexual relations), mentioned or included in the definition of marriage. According to their arguments, including the arguments regarding the adoption or raising of children by same-sex couples, the necessary and sufficient conditions for having and raising children is the presence of philo, which according to their argument is equated with marriage. Even though they are correct in saying that those raising children need philo they immediately preform the fallacy of equivocation by equating philo (and even philia) with eros. They reason that because eros is a type of love and (at least in English) philo is also a type of love, then they must be the same thing. Again this way of thinking and this conclusion immediately leads to a fallacy of a suppressed correlative, because if philo and eros are the same thing then either we must have sexual relations with everyone we are friends with (that is we share a form of philo with) or we can only have philo with those we also share eros with.
In effect, they argue that their eros must be accepted solely because they also share philo. In other words, they argue that their homosexuality, and all the acts that they preform, must be acceptable simply because they have made a philo type commitment to another person. On this basis I can think of a good argument for accepting organized crime (as long as it is kept in the family, by marriage). Thus the true problem is not that two people have philo and wish to attempt to raise children (after all we let priests and nuns do that, and they usually do pretty well) but that in addition to their laying claim to philo, they wish to equate it with eros, and herein lies the problem, and why we cannot agree.