If the casual sex is between CONSENTING adults, why should it matter to you regarding any commitment?
Well there are two separate issues here.
The first question is what effect the casual sex has on the consenting adults - whether it has a positive or negative effect on them.
The second question, which is quite separate, is whether society has any business controlling actions which do not directly hurt others - for example consumption of drugs, alcohol or casual sex.
For the first question...Everything in life produces some kinds of effects, negative and positive. It is up to one's intellectual and emotional maturity to decide if one is ready to cross that threshold from being comfortable with the known to being uncertain in the unknown.
Dead Yemeni child bride tied up, raped, says mom - Yahoo! News
SHUEBA, Yemen A 13-year-old Yemeni child bride who bled to death shortly after marriage was tied down and forced to have sex by her husband, according to interviews with the child's mother, police and medical reports.
The girl certainly was a virgin and the sex, even though forced, was certainly inside marriage. But was she readied in intellect, emotional and physical maturity to handle sex, even though inside marriage? We can see after the fact that -- not.
The point here is that the greater the intellectual, emotional and physical assets we have the greater autonomy we demand and therefore it is only right, based upon that demand for autonomy, that we should leave the judgment of negative or positive effects to the consenting adults in question 1.
Which lead us up to question 2.
Every time we allow 'society' or the representative of 'society', aka the 'state', to adjudicate what is 'good' or 'bad' for the entire society, we lose a bit of the autonomy we demanded. That by itself is not bad for we understand that if we want to live in relative harmony with our neighbors, some limits must be set and obeyed. Do I want to go 100 mph on my bike? You bet. Should I go that fast in a residential area? No and it is agreed that a speed limit, aka restraints on me, be imposed and punishments declared for violations.
But question 2 begs another question, which is to what
DEGREE should the state intrude into our lives and impose limits to our autonomy based upon sequential and inevitably increasingly abstract effects of our actions? In other words, because we live in a community, everything we do affects others in some ways and many of the effects are unseen and require time to manifest themselves. To what degree should the state punish or reward a person based upon those effects?
If I go 100 mph in a residential area, a possible effect is that I could kill a child. Should I be punished for that immediate effect? Yes. But one could argue that since I set a 'bad example' for other children, I should be punished further just in case one of those children turned out to be a juvenile delinquent later in his life.
If a woman is known to be an easily available sex partner, one could argue that she is setting a 'bad example' for young girls and some of them might turn out to be less than desirable mothers because of what they learned from this woman, and so on...and so on...
In the abstract, both above arguments are valid but only one has a potential immediate and negative effect -- the 100 mph motorcycle rider in a residential area. The state is within reasonable rights to proactively punish some actions that may produce immediate and negative effects. If a policeman, an agent of the state, sees someone attempting to break a door, he does not wait until the person is actually inside the house before he does something. He is compelled to be proactive because the negative effects of a burglary is physical as well as emotional. But it is the physical effects that is the most compelling. What if the man is the owner of the house and he is breaking the door because he lost his keys? So of course we do not enact laws that say it is illegal to break doors, only that it is illegal to break doors that are not yours. In this case the policeman may even help the homeowner break into his own house.
As we can see, even when we have what we believe to be clear cases of where the state can intrude itself into our lives, impose limits and mete out punishments for violations of those limits, there are still situations where upon examinations, punishments are not deserving, like the man who was caught breaking into a house only for us to find out he was breaking into his own house because he lost his keys.
Fornication is defined as sex outside of wedlock and is usually associated with a moral standard. The direct recipients of this type of sex are the participants, no one else. The effects are uncertain. Or highly abstract. Absent any direct physical negative effects, the state is presumably excluded from intrusion, impose any limits and mete out any punishments, based upon the lack of immediate negative effects. So where did the state received its permission to proactively punish potential sex partners who are not married to each other and to punish
ex post sex partners who are not married to each other?
Let us be honest about our human nature here.
Laws regarding fornication is primarily about petty human jealousy. It is only with the mental gymnastics of religions can anyone be convinced that someone else enjoying sex outside of marriage is a negative to society. This is about petty human jealousy hiding behind the morality and religious shield and the state is the thrown spear from behind said shield.
