Morality deals with topics of virtue, rightness, or goodness. Often, confusion and disagreement arise when ideas about virtue or goodness conflict, usually along religious, ideological or traditional lines — what you think is right is probably not completely compatible with what those think from different religions or cultures. This conflict is avoidable if we restrict our discussion of morality to the minimum standard required from everyone in society. This minimum standard is useful because it is precisely the line where we can enforce laws and talk coherently about justice.
Now let’s talk about sex. Like essentially all human activities, sex can and does have a standard of morality attached to it. The point at which the law is concerned with sex is where we can talk about a “baseline morality”. For now, we’re not concerned with ideological or religious moral views of sex — just the baseline that would be incorporated into the law. At the most basic level, there are two factors involved with the morality of sex: maturity and consent. Of all possible factors to consider for any sexual encounter, these two alone are enough to define the baseline morality that should be upheld by the law.
Without maturity — the experience, awareness and ability necessary to make a significant decision for oneself — a person involved in a sexual encounter can’t take responsibility for consent, which is the most important factor when evaluating the morality of a sexual encounter. Based on the most fundamental notion of individual rights, each person must decide on their own which relationships and encounters to embrace, without coercion or duress. This requirement is no different in the realm of sex, and is precisely what is meant by consent.
In any given sexual encounter, then, we can simply look for maturity and consent to evaluate the baseline morality, and thus the legality involved. How exactly to measure maturity is not quite as straightforward, but a workable definition using the median agreement of maturity in a community will usually be sufficient. This simple change in evaluation leads to many results that will be surprising and even offensive to many subscribers of arbitrary traditional or religious moralities. Still, it should be obvious that it is not the job of the law to enforce any particular arbitrary morality, but rather to uphold and defend each individual’s rights from infringement by others.
Some of the sexual acts that can be called “moral” at this baseline level, and thus should be strictly legal, include: heterosexual sex, homosexual sex, interracial sex, interfaith sex, group sex, polyamory, incest, premarital sex and prostitution. Notice that as long as maturity and consent are present, sex for any particular reason is perfectly moral, including sex for love, procreation, fun or money. The fact that these acts should be legal based on this baseline morality does not mean that they are necessarily good ideas, but simply that it is unreasonable to make them illegal based on the law upholding individual rights. Each person in society is free to add their own personal morality on top of the baseline to define those sexual acts that they will participate in, but they are not free to compel others to adhere to their personal opinions — only the law may compel.
It is also important to understand the types of sexual acts that are immoral under this scheme — sexual crimes. None surprising or terribly controversial, they include but are not limited to: rape, which lacks consent; sex with children, who lack maturity; sex with animals, which by median community standards most likely lack maturity; and sex between a husband and wife where either one withholds consent. The only room for debate when questioning the morality of a sexual act, assuming each person is forthcoming and truthful about their consent or lack thereof, is in the judgment of maturity. For this reason, one could see the laws varying slightly between different cultures that have different ideas of what makes an individual mature, but that is the only place at which cultural considerations should enter into the question.
All of that said, keep in mind that we are only discussing sexual morality concerned with a sexual act; there are many other systems of morality that may apply to any given act. For instance, if a married person has sex with someone outside of their marriage without consent of their spouse, that act could be sexually moral while at the same time violating a morality of marriage or partnership. All of those alternate moralities, though, cannot change the fundamental rights-based approach of using baseline moralities for the definition of the law surrounding the morality of sex.
Overall, I mean to highlight the consequences of reasoning from fundamental individual rights to simple rules that, when applied, may lead to interesting or surprising conclusions, but nonetheless are indisputable insofar as they support the concept of each person’s freedom from coercion. I hope that everyone will appreciate the consequences of respecting others’ freedoms, even if they don’t necessarily agree with the decisions that others make; that is a society where we will all be freer from the prejudice and intolerance that run rampant through our lives.