One of the hot button issues in our culture is homosexuality and the related issue of same-sex marriage.  I have offered a non-religious argument against both (here and here).  As I have continued to reflect on these issues, however, I am persuaded that a non-religious case against homosexuality is much more difficult to make than the case against same-sex marriage.  One reason for this is the fact that the case against same-sex marriage can be made purely on policy grounds without any recourse to moral judgments.  One could believe homosex is morally irrelevant and still be opposed to the government regulating same-sex relationships.  Moral judgments, however, are not so easily divorced from one’s view on homosex.

Take for example the argument from natural law.  We argue that the natural purpose of our sexual organs requires heterosexual sex.  To use our sex organs in such a way that their natural purpose cannot be realized is morally wrong.  There are a few reasons why this will not be convincing to many who think homosex should not be opposed.

First, most people today are completely unfamiliar with the concept of natural law.  While we may bemoan this fact as an intellectual shame, it remains a fact nonetheless.  If people are not familiar with natural law, they are unlikely to see the force in natural law arguments.

Even if someone understands the natural law argument, if they do not believe in God or if they are a moral relativist, they can still reject the force of the natural law.  After all, while the natural law can show us the natural biological purpose for human sexuality, if there are no moral facts and if there is no God to be morally accountable to, who cares if we ignore the dictates of natural law?  We are not behaving immorally for doing so, and there is no one to judge us for it either.

Why should anyone think there is a moral dimension to the natural law?  If I buy a computer to use it as a paperweight, there is no question that I am not using the computer for its intended purpose, but clearly I have not done anything immoral.  I just spent a lot of money on a paperweight!  While that may speak volumes about my intellect, it doesn’t say anything about my moral character.  Why couldn’t the same be said of homosex?  One could agree that homosex is unnatural, and yet argue that there is no moral dimension to it.  Homosex may be unwise, pointless, or even inferior to heterosex, but that does not make it immoral.  It’s just two bodies clashing together.

Also, what about sexual activities like oral sex or masturbation?  Many who oppose homosex on the basis of natural law see nothing wrong with oral sex and masturbation.  If the natural purpose of our sexual organs is only fulfilled by vaginal sex, and we have a moral obligation to use our sex organs according to their natural purpose, then not only is anal sex unnatural and hence immoral, but oral sex and solo sex are unnatural and immoral too. [Graphic content alert] The same natural law that tells us the natural function of the penis cannot be realized when inserted into an anus is the same natural law that tells us the natural function of the penis cannot be realized when inserted into someone’s mouth or hand.

The natural law proponent could bite the bullet and admit that oral sex and masturbation are also unnatural and hence morally wrong, but not all would be willing to do so.  Those who aren’t willing to cede this could respond by arguing that what makes a sex act unnatural is not merely the fact that one is using their sexual organs in a way other than that for which it was intended, but the fact that they only use them in a way they were not intended to function, thereby thwarting the fulfillment of their natural purpose.  So if the only kind of sex acts one engaged in were oral and solo sex, they would be violating the natural law.

While this refinement works to show why sexual behavior that is exclusively homosexual in nature is wrong while oral and solo sex among heterosexuals is not, it is powerless to show why homosexual behavior is wrong for bisexuals who engage in both homosexual and heterosexual acts. They, like their heterosexual counterparts, have not prevented their sex organs from fulfilling their natural purpose, and thus their homosexual acts are no more unnatural than oral sex acts among heterosexuals.  Would any of us who are opposed to homosex admit that homosex is morally acceptable as long as one also engages in heterosex at some point in their life?  No.  Does this mean, then, that the natural law argument begs the question (unless one is willing to say that the only moral form of sexual activity is sexual intercourse.)?  Not necessarily.  The natural law proponent might respond that to obey the natural law one needs to do more than merely engage in heterosexual intercourse at some point in his/her life. Rather, one must be capable of engaging in and actually engage in heterosexual intercourse with every partner with whom s/he engages in sex acts. Since there is no way for two people of the same sex to fulfill the natural law in their sex acts, two people of the same-sex should not be engaging in any sex acts together. This is reasonable, but one might be hard pressed to defend the claim that otherwise unnatural sex acts are morally acceptable in a sexual relationship so long as one is also engaging in natural sex acts in that same relationship.  One would have to provide a principled reason for this requirement to avoid the charge that it is ad hoc.

In the end, the best reason to oppose homosex is because God is opposed to it.  Homosex is a violation of His creative purposes for humankind and human sexuality, and as such, He commands us to avoid homosexual behavior.  As a proper moral authority, God has the right to make such a command, and we have a moral obligation to obey it whether we like it or not.

I don’t think our non-religious arguments against homosex will persuade those who are not already inclined to agree with our conclusion.  Atheism and moral relativism undermine the cogency of the natural law argument, and even among theists and moral objectivists, the force of the argument is often lost.  This is not to say that the natural law argument is a bad argument, or that there are no good non-religious arguments against homosex.  I think it is a good argument, and that it is one of several good non-religious arguments against homosex.  I just don’t think their force is such that they will compel the opposition.  While our arguments may not be so compelling that people would have to be irrational to disagree, our arguments at least demonstrate to the non-Christian that the Christian position on the morality of homosex is a rational position rooted in something deeper than religious dogma or animosity.  And that is quite an accomplishment!

What are your thoughts on the matter?