As humans, we are rightfully proud of our capability to engage in philosophical contemplation. On the other hand, the effect of philosophical contemplation on decisions of how we conduct our lives is often overestimated. Indeed, our opinions, and whole belief systems, typically depend heavily on the modes of production, rather than what we regard as our independent intellect.
Let's take sexual morals. We assume that our sexual morals are primarily dependent on our metaphysical outlook, or esoteric systems such as religions. In Islam, sexual intercourse outside marriage is considered a crime against God, while murder is one just against a fellow human. And in Christianity, marriage is a sacrament, which gives it divine character.
In a non-religious setting, modern society punishes sexual transgressions more severely than other crimes. This only makes sense on the base of special moral considerations.
However, sexual morals, just as all forms of ideological superstructures, depend far more on the modes of production of human societies than on philosophical insight.
One aspect of particular importance is the degree to which a human society is capable to produce the absence of sexually transmitted diseases. Diseases, caused by pathogens, are a fact of nature. The capability of human societies to prevent or to cure them depends on the modes of production.
In this respect, the productive capabilities of traditional societies were very limited. They knew how to ammeliorate symptoms with herbs. Compared with the productive capabilities of modern societies (which not only can properly diagnose diseases but also cure them with antibiotics and the like), the modes of production of traditional societies were very limited indeed.
Throughout history, a high degree of monogamy, enforced by the state or religions, did have undeniable advantages because general libertinage would have left much of a society crippled by sexually transmitted diseases.
Sexually transmitted diseases, in this context, are not restricted to classic venereal disease such as gonorrhea, syphilis, and chlamydia. For a historic perspective, one will have to include pests such as scabies and other diseases that are transmitted through close physical contact, whether sexual or not.
Scabies, caused by itch mites that are too small to be seen by the naked eye, would have reached epidemic proportions in any sexually liberal society much faster than gonorrhea or syphilis, and the disturbing factor likely was or would have been much graver.
Scabies is not primarily transmitted by sexual intercourse, but by plain skin contact, which, however, is most likely to occur between adults when they have sexual intercourse.
On the other hand, I wonder whether the Catholic approach (not to get fully undressed during sexual intercourse) has to do more with putting up a barrier against scabies rather than the devil.
Intense skin contact of a minute or two is enough to transmit scabies from one human host to another. Once on a human host, the whole body will sooner or later be covered with pimple-like eruptions causing an unbearable itch.
Nobody can withstand the scabies itch without scratching, thus causing a second lawyer of infection, this time bacterial and fungal.
People don't die from scabies, the "seven-year itch". But they can die from the bacterial infection that constant scratching induces.
The epidemiological control of scabies also always was much more difficult than of classic venereal disease such as gonorrhea or syphilis, both of which require genital contact. Scabies actually will not only affect two sexual partners, but immediately most of their private environments. It's usually not a single person who is infected, but a whole household.
If a household's teenage daughter has sexual intercourse with an infected outside man, than her mother and father, and her brothers and sisters, and their children, and the in-laws, will likely all be infected within days, and it may be weeks before symptoms occur. The danger is all the greater the poorer the family, and the more crowded the family home. Most of those infected will not or would not have died for years, but would have been miserable with the big itch until their death.
While the disease can be treated today, in a historic setting scabies and other sexually transmitted diseases, rather than philosophical contemplation, lead to restrictive sexual morals. People did not adopt monogamous morals out of philosophical contemplation or piety. Rather, they became monogamous in order to escape sexually transmitted disease of epidemical proportion, and then subscribed to congruent religious or philosophical systems because that looked so much more noble than blaming it on sexually transmitted diseases. Their sexual morals were, and are, but an ideological superstructure for the lack of productive capabilities to control sexually transmitted diseases (a deficiency of the modes of production).
That pious men who indeed avoided all physical contact, and never were naked, were likely to remain free of scabies and other sexually transmitted disease was taken as perfect proof that a certain god meant us to be abstinent, or at least monogamous.
