Chris Meyers’ latest book, A Moral Defense of Homosexuality: Why Every Argument against Gay Rights Fails, is the latest in recent attempts to provide a robust philosophical account in favor of the modern liberal position on homosexuality. By “the modern liberal position,” I mean the view that homosexual activity between consenting adults is morally good, same-sex unions are on a par with other marriages (and ought to be considered as such), same-sex couples should be allowed to adopt, and gays ought to be allowed to serve openly in the military.

Meyers’ book is long overdue. If you wish to persuade people that they ought to view same-sex unions as morally good, then you will need also to give good reasons why homosexual activity is morally good. The difficulty is that, historically, the modern liberal position has lacked any robust philosophical argument in favor of homosexual activity.

Meyers attempts to provide such a robust philosophical case for homosexual activity. He attempts to justify not only homosexual activity, but also same-sex unions, same-sex couples’ adoptions, the rights of gays to serve openly in the military, and restrictions on the religious liberties of businesses that refuse to bake cakes for gay wedding. While I agree in part with some of Meyers’ points (such as allowing gays to serve in the military) and respect that he has given much thought to this issue, most of what I have to say is by way of disagreement. Since so many of his arguments are wanting, I will restrict myself here to some criticisms of his arguments concerning: a) traditional natural law ethics, b) the perverted faculty argument, and c) the nature of marriage.

Natural Law Ethics

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Meyers claims that traditional natural law arguments against homosexual activity are easily dismissed, because, he claims, natural law theory is an unsound moral theory. However, Meyers’ attempt to refute traditional natural law theory largely hinges on various mistaken notions of the word “natural,” none of which is what traditional natural lawyers mean when they say something is contrary to the natural law.

According to natural law theory, the natural law is “an ordinance of reason promulgated by one who has authority for the common good of man.” Traditional natural lawyers argue that human reason can discern this natural law by reflecting on our true nature and its natural inclinations, powers, and operations. To be good, we must order ourselves to what we are for—in other words, to what perfects our nature. Just as a tomato plant is good because it does what it is for (i.e., it acts according to its nature by growing, nourishing itself, and producing fruit, etc.), so too humans are good because they act according to their nature. Just as a tomato plant that does not produce good fruit is a bad tomato plant (and so does not act in accordance with its natural ends), so too humans become bad by not acting according to their natural ends, such as reason.

Meyers’ criticisms of natural law all hinge on equivocal senses of nature: nature as opposed to miracles, nature as opposed to the unusual, and nature as opposed to the artificial. Yet none of those senses is what traditional natural lawyers mean by saying, “x is against the natural law.” When Aquinas called homosexual activity “a sin against nature,” he did not mean “nature” in the sense of “mother nature,” what usually occurs, or what is not made by man. On the contrary, he meant that such acts are against the natural end of the use of the generative power. For more on this, I refer the reader to my published academic work.

According to traditional natural law, when x is said to be “against the natural law,” this means x is wrong because it is contrary to what perfects man’s nature. “X is wrong” because it is against reason, against temperance, against justice, against fortitude, against the common good, or some other end that perfects man’s nature. Meyers’ arguments against traditional natural law are straw-man arguments. This is not surprising, given that he appears totally unaware of any of the traditional natural law scholars such as Steven Jensen, Ralph McInerny, Steven Long, Edward Feser, or J. Budziszewski.

The Perverted Faculty Argument

Among the arguments Meyers attempts to debunk is the perverted faculty argument against homosexual activity. This argument, which is intimately connected with the traditional natural law account, comes in various versions. Its key premise is that using a human faculty or organ contrary to its purpose is immoral.

Meyers offers a decent critique of the argument. Unfortunately, he fails to engage the scholarly literature on this issue. Timothy Hsiao, Edward Feser, J. Budziszewski, Thomas Aquinas, and I—among others—have all given philosophical defenses of this argument. Yet none of these authors is cited anywhere in Meyers’ discussion. As a result, Meyers misses some key distinctions.

Meyers critiques the key premise of the perverted faculty argument by claiming that although the purpose of the feet is to walk, there is nothing wrong with using the feet for kicking, or standing, or pedaling a bike. Since there is nothing wrong with using the feet for these contrary purposes, Meyers argues, so too there is nothing wrong with using the sexual organs for the contrary purpose of homosexual acts.

If Meyers had read a bit more widely, he would know that his objection has already been answered by Feser, Budziszewski, and Hsiao, who make distinctions to avoid Meyers’ apparent counterexample. As Hsiao writes, “it is not inherently wrong to enhance or to impose another purpose of our own on top of a faculty’s natural function, so long as it is consistent with its function being achieved . . . a person who uses his tongue to lick stamps is still tasting.” Thus, a person who uses his feet to pedal a bike or kick a soccer ball is still using them for movement, which is the natural purpose of the feet. But in homosexual activity one is not imposing another function onto the natural function of reproduction. Rather, one is using the generative organs contrary to their natural end of reproduction (for acts not reproductive in kind).

While some versions of the perverted faculty argument have real intellectual weaknesses, Meyers’ work has missed the best version of the argument, as found in Aquinas’s De Malo Q15, A1. According to Aquinas, the argument against homosexual activity is as follows:

1. any action not ordered to its due end is a disordered action,

2. the due end of the use of the sexual members is the generation and education of offspring,

3. so any use of the aforementioned members apart from such ends (as in homosexual activity) is disordered.

Like most other scholars arguing in favor of homosexual activity, Meyers not only fails to address this De Malo argument from Aquinas, but his main positive argument in favor of homosexual activity suffers from serious objections. Meyers argues that any action that does not cause harm, nor violate a competent person’s autonomy, and is not unfair, and does not violate someone’s rights is not morally wrong. Since homosexual activity does not cause harm, nor violate autonomy, is not unfair, and does not violate anyone’s rights, Meyers claims, it is not morally wrong.

Unfortunately, it logically follows from Meyers’ major premise that gluttony, hatred, unforgiveness, impatience, pride, neglecting one’s natural talents, excessive anger, and necrophilia are not morally wrong, nor are they vices if practiced continually. For none of these actions necessarily causes harm, nor violates anyone’s autonomy, nor are they always unfair, and neither do they always violate someone’s rights. Therefore, the central argument of Meyers’ book fails.

The Nature of Marriage

Meyers criticizes the arguments put forth by Sherif Girgis, Ryan Anderson, and Robert P. George that the nature of marriage shows that same-sex unions cannot count as real marriages. Meyers claims that Girgis, Anderson, and George’s account depends on marriage having an objective nature. Meyers argues that if marriage has a real objective nature, then it either has a nature just as natural kinds do (like trees, dogs, and frogs) or it has a Platonic essence. Since marriage cannot have a nature in either sense, Meyers says, it follows that it has no objective nature at all.

What Meyers has proposed, however, is a false dichotomy. Marriage has a nature in the way in which the family or language has a nature. At its core, there is something that makes a family a family; if you take that essential feature away, it ceases to be a family. You can have a family of a man and woman and their children, but you cannot have a family of rocks. Certain aspects of family may change over time, but at its core there is something essential. Similarly, language has many features that can change: intonation, rhythm, declensions, grammar, and so on. But at its core there are certain essential aspects that remain constant across all cultures; if you take away one of these essential parts, you cease to have language. So too is the case with marriage. There have been all sorts of variabilities regarding certain peripheral aspects, but at its core it has always (or for the overwhelming most part) been understood as taking place between a man and a woman. Just as language has an objective nature without being a Platonic essence or a natural kind, so too does marriage have an objective nature.

Meyers wants to straddle two seemingly contradictory propositions: a) marriage is totally determined by social convention, and b) this does not show an “anything goes relativism.” But if the nature of marriage is completely determined by arbitrary human whims, then it logically follows that marriage can be between four people, a man and his dog, or a man and his car, if enough people agree to define it that way. Perhaps what Meyers means is that we are not likely to redefine marriage in such ridiculous ways any time soon. Point granted. Yet the same would have been said about same-sex unions and the nature of marriage just thirty years ago.

Like language, marriage is a social institution that has certain objective features based on human nature, although certain peripheral aspects of it can change over time or from culture to culture. A reliable guide to discerning what the essential features of language or marriage are is to see what the overwhelming majority of philosophers and our ancestors thought it was—and to attend to their arguments. The historical consensus shows that at its very core marriage necessarily involves the type of union that tends to result in new human life. Certainly other features such as romance, emotional bonding, and sharing of material goods are important to a fully flourishing marriage, but strictly speaking the natural order towards the type of union capable of creating new life is a sine qua non for what makes marriage to be marriage. Only the union of a man and woman fulfills this requirement, and this is what the overwhelming majority of our ancestors recognized. Infertile man-woman unions still retain this natural order to new life, even though a defect prevents them from accomplishing it. Same-sex unions, by contrast, are essentially sterile (not being due to a natural material defect) and so their union cannot fulfill a basic necessary condition for a marriage.

Meyers’ new book is novel in its attempt, but fails to provide any sound basis either for the morality of homosexual activity, or to show that marriage’s essential nature is as arbitrary as mere social convention. Despite deep disagreement, I still wish to thank him for his contribution to the debate. May truth infused with true charity win.