some rational claims against sexual promiscuity-
- it can lead to the spread of disease
- it can make it difficult to raise a family and children
- it makes it hard to trust someone and build strong relationship bonds
- it can engender objectification and negative self worth in people
1. I agree with the first point, so no comment (there's even a group of diseases spread only through sex, which are called STDs (so no, AIDS technically isn't an STD)).
2. I don't see how it makes it more difficult to raise children.
I think you're talking about kids being pregnant? If people in general, were more open minded about sex, they might also accept that their children are having sexual relationships as well. If parents acknowledge that, they might be able to help prevent the girls from becoming pregnant by supplying condoms and/or the pill. They might also ask their daughters if they had taken the pill & take them to the doctor for a morning after pill if the answer was no.
So yes, it would recquire a certain amount of responsibility from the parents, but isn't responsibility a part of raising children in general? (although a lot of parents these days seem to be forgetting that)
3. Once again, I don't see how it makes it hard to trust someone and build strong relationship bonds.
As far as I know, a good relationship is based on love and mutual agreements and trust is based on how well you both live up to those agreements. If someone wants to have an open relationship & you don't, then the relationship simply will not work. These days such a person would simply cheat on you behind your back, whereas if people were more open about it, they might be honest about it & in my eyes become more trustworthy.
4. I partly agree, but it's already happening right now (every 20-30 year old single guy can add 1+1), so I doubt it would become a bigger problem if people were more openminded about sex.