I'm re-reading a favourite book: Sex, Drugs, Death, and the Law, by David A.J. Richards. My immediate interest is Richards' theoretical account of the limits of the criminal law, but he is very good on the specifics of issues.
Throughout the book, he argues against over-criminalisation of such things as homosexuality, prostitution, drug use, and euthanasia, basically relying on solid liberal arguments for non-intervention by the state in matters of personal choice (in the absence of secular harm). This is all solid stuff. However, I am pleasantly surprised - since I'd forgotten - how impressive he can be when analysing the history and content of various moral ideals that the state has so often promoted into a public morality and attempted to impose by law.
At one point, he nicely picks apart one of St. Augustine's famous arguments: that sex is something inherently shameful and degrading. Augustine argued that human beings universally insist on (1) having sex unobserved and (2) covering their genitals in public. He concluded from this that the only explanation for such facts is that we experience sex as inherently degrading because it involves loss of control, and it can be made morally acceptable only by a controlled intention to procreate.
Augustine's two facts are, in any event, open to some debate and qualification, though the first is typical of human beings in all cultures and the second could probably be restated more accurately without totally undermining Augustine's point. There are various things that can be said about such facts from an anthropological perspective, but Richards makes a nice point that applies to the first one, in particular, though it might also have a connection to the second. Most of us would, indeed, be embarrassed to have sex in front of an audience, and I'm confident that public sexual performances are altered by the fact that those concerned are attempting to put on a pose and keep something about themselves concealed. But this embarrassment factor is not because we think sex is inherently degrading.
Richards attributes our unwillingness to be observed publicly, while having sex, to the familiar fact that sex is a "profoundly personal, spontaneous, absorbing experience" in which the partipants "express intimate fantasies and vulnerabilities which typically cannot brook the sense of an external, critical observer." Sex is the kind of thing that requires privacy - not many of us want to be open to scrutiny from the world at large when we are in many ways at our most vulnerable and trusting, lowering the layers of psychological (as well as merely physical) self-protection that we need for other activities. As Richards suggests, this doesn't entail that we feel ashamed about sex or about our nature as sexual beings.
I think that this is all plausible and that Richards expresses the idea very well.
Doubtless, many people do feel some kind of shame or disgust about sexuality and sexual acts; they may base their moral beliefs on such feelings, and try to elevate those beliefs to the level of policy, imposing them on others who don't share them. I should add that the psychological basis for these sex-negative feelings may go beyond the point that Richards makes (the one about our feelings of vulnerability that make most of us unwilling to be observed in moments of sexual intimacy with our lovers). In addition to Richards' point, I expect that some folks have more deep-seated feelings of fear or disgust, or suspicion of our animal nature, or some mixture of these and similar things. Some might (I can imagine) have these feelings even in the absence of cultural teachings that instil or reinforce them. But none of this, of course, provides a rational basis for drawing conclusions about the inherent moral character of sex, let alone for advancing beyond that to conclusions about public policy.