The strongest argument against same-sex marriage””in the sense of the argument with the deepest philosophic roots, or the argument that gets to the most fundamental issues at stake””is that homosexual activity is contrary to the natural law. This argument is either true, or it is not. If it is true, then publicly sanctioned same-sex marriage will contribute nothing substantial to the happiness of homosexuals. There are various understandings of natural law, but all present the natural law as a reality that exists independent of human opinion, a rule for human flourishing that human beings can ignore only at their own peril. On this view, the real issue in human happiness is the moral quality of our lives and not how they are regarded by society at large. As Socrates explains to his young interlocutors in Plato’s Republic, the actual being of the soul, and not its mere seeming, is decisive for human happiness. That is to say, happiness is the fruit of the proper functioning of the human soul, so that character, and not reputation or opinion, is the source of genuine flourishing. On this understanding, Socrates explains, a just soul, one ruled according to reason, is happier than an unjust one, regardless of whatever praises are heaped upon the successfully unjust man by a corrupted public opinion.
Accordingly, if homosexual conduct really is, as its natural law critics contend, a perversion of human desires and capacities, a wrenching of them away from their natural purposes, then such conduct will be a source of frustration and unhappiness regardless of whether society bestows its “recognition,” and hence its approval, on it. On this view, there is nothing of substance to be gained from same-sex marriage even for homosexuals. Indeed, if traditional natural law theorists are correct in their assessment of homosexual conduct, then same-sex marriage would be not only pointless but positively damaging, to the extent that it could mislead people to their own harm by bestowing a spurious respectability on an objectively disordered way of life.
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