In New Mexico, a woman and her son are fighting in the courts for their “right” to a sexual relationship. Monica Mares and her son were separated when she gave him up for adoption, but fell in love when they were reunited. Monica has said she is willing to go to prison and, indeed, give up custody of her other eight children if need be; the case has sparked a discussion of the next bastion of “marriage equality”: “consanguinamorous” marriage.

Aristotle once wrote that “a small mistake in the beginning is multiplied later a thousandfold”. He was criticising Plato’s approach to ethics and the soul, which he saw as too concerned with parts of the human being and not enough concerned with the whole. Those who take his dictum seriously, especially as it relates to human beings in the area of love, sex and marriage, should not be too surprised by the above story.

If our only moral concern about sex is whether it is consensual and perhaps involves a couple “in love”, then it hard to see why the case should scandalise so many. Why, for example, should the law get involved? The couple have made a contract (or at least a compact) and if we think about morality in terms of contracts, why should anyone object?

Of course, talk of contracts is usually a way of avoiding deep moral questions. When it comes to sex, this avoidance is particularly serious. The philosopher Aurel Kolnai wrote: “It is because we experience sinful sexual experience in sexual sin, and not primarily the logical web of relations and their oppositions, that there is inherent in this attitude of moral disapprobation an importance and absoluteness which has no parallel.”

Sexual phenomena are indeed in some sense “special” and have an importance that cannot be reduced or eliminated, despite attempts to see the moral significance of sex only in terms of consent or pleasure or generic emotional experiences of bonding. And such a thought is not alien to secular writers such as Howard Jacobson and Jonathan Franzen: writers who, by no means strict themselves on these issues, nonetheless decry the trivialisation of sex in contemporary culture. Jacobson has contrasted the truth and majesty of “Thou shalt not commit adultery” with Richard Dawkins’s modern rendition: “Enjoy your own sex life (so long as it damages nobody else) and leave others to enjoy theirs in private, whatever their inclinations, which are none of your business.” The latter puts forward a view of sex so trivial it can’t begin to account for the multiple deep phenomena we associate with sex. As Jacobson puts it, the real Commandment “shakes us to the core. There is reverence and trembling in it. ‘Enjoy your sex life’ makes sex sound like a good breakfast.”

The moral importance of sex has deep roots. Sexual acts between a man and a woman can result in new lives being conceived, and the natural, lifelong, exclusive institution of marriage generates specific moral obligations helping to safeguard everyone involved. It is the connection to having children which requires that there be this institution, even if some marriages are infertile. The procreation and raising of children is not a purely private concern of the parents but part of the common good of society. If we reflect on the nature of marriage and its importance in terms of the good of children, the good of parents and the wider good of society, it becomes clear that changes in perceptions of the purpose and nature of sex will have radical effects on how society functions.

​How to continue reading…

This article appears in the Catholic Herald magazine - to read it in full subscribe to our digital edition from just 30p a week

The Catholic Herald is your essential weekly guide to the Catholic world; latest news, incisive opinion, expert analysis and spiritual reflection