The Procreation Argument
One interesting thing about the arguments against allowing same-sex marriage is that they are so often fallacious or based on false premises. As a philosopher, I would certainly accept a good argument against same sex-marriage. However, I am still waiting for such an argument. Well, other than the good arguments against marriage in general.
One argument that gets trotted out is the procreation argument. The gist of this argument is that the purpose of marriage is procreation, same-sex couples cannot procreate naturally, therefore same-sex marriage should not be allowed. This is, obviously enough, a bad argument against same-sex marriage.
First, the purpose of marriage does not seem to be procreation. Obviously, marriage is neither a sufficient nor necessary condition for procreation. It might be replied that marriage exists to provide children with a healthy environment. However, since the people who are actually experts on the health of children support same-sex marriage, this approach would fail. Also, obviously enough people are not tested for their suitability as parents before they are allowed to get married, nor are they compelled to divorce if they prove to be unsuitable parents. Naturally, I would support the principle that people who would be awful parents should not have children-but this would not deny same-sex couples the right to marry or have kids simple on the grounds they are same-sex couples.
Second, there is the matter of consistency. If it is claimed that same-sex couples should not be allowed to marry because they cannot procreate naturally, then it would follow that different-sex couples who either cannot or chose not to procreate naturally should not be allowed to marry. If we accepted the procreation principle, couples would need to be tested for fertility before being allowed to marry and would need to produce offspring in a specified amount of time or have the marriage nullified. This is, of course, absurd and something that we surely would not impose on different-sex couples. As such, the procreation principle should be rejected.