A very interesting piece on incest by Margaret Somerville:
Some people propose that just as laws criminalizing homosexual acts or limiting marriage to monogamous heterosexual unions have been changed, the law against incest should be repealed. They argue this law is outdated, does not reflect current social mores and is nothing more than imposing one view of morality on others in a context where personal privacy should take priority.
Underlying their approach is the belief that personal preference is the guiding principle regarding one’s sexual activity and that what one does, as long as it is among consenting adults, causes no harm to anyone else.
Their definition of harm is very narrow. Any concern about harm to children who might be conceived as a result of incest or the harm it does to family structure, relations and functioning, and thereby to society and its values, is not on the radar screen. So, if a grandfather wants to have sex with his 18-year-old granddaughter and she consents, it is no one else’s business but their own.
Those making the case for legalization reject the idea that incestuous conduct might be inherently morally wrong. Rather, moral relativism governs – that is, the decisions of the persons involved as to the ethics of their conduct are conclusive. Ethics becomes nothing more than personal preferences.
I used to be a libertarian. I used to think that as long as one didn’t hurt anyone else, one was allowed to do anything one wanted. That what consenting adults got up to was their business and no one else’s. Part of me still believes that. But I also realized, somewhere along the way, that I was probably guilty of having a definition of harm that was too narrow. And that when in doubt, one should always make sure children (who are inherently more vulnerable than adults) are reasonably well-protected from harm. I have never been able properly to explain why gay marriage made me uneasy, especially because homosexuality, and homosexual behaviour, do not have the same effect on me. But part of is certainly has to do with a very strong instinct to reject ethics as “nothing more than personal preferences.”by