"If a man clearly rapes a young girl, she reports this, and he claims that she consented at the time but changed her mind later, he might get off due to reasonable doubt. The AoC means he won't get off if she is underage."
But if a man clearly raped a young girl, he won't get off despite his claim that she consented at the time but changed her mind later.
I wrote imprecisely in saying he "clearly raped a young girl". I meant that if we had been there watching we would have known that -- not that when we're hearing the story later it is entirely clear.
The AoC prevents an evidence based investigation.
True. Your original premise was weighing costs and benefits. I suggest that the benefit of protecting underage girls from rape when evidence is weak is more important than deterring desired relationships.
For young teens, they probably don't and maybe even shouldn't get into lifelong relationships
Would they really completely understand that the relationship is temporary? I don't think most girls are wired that way (the landscape does look on average quite different for gay young-teen boys).
Also, look at what IS allowed: they can have non-sexual friendships and flirtations with older people. They can experiment sexually with their peers. You agree they probably shouldn't be thinking long-term. So what they give up is short-term sexual relationships with older people? This benefit is looking awfully slim in application and importance.
what was bad was the man's false promise. his using his false promise to have sex with her is not bad...
(yes it is)
... because if that's what happened, then the woman likewise used sex to attempt to get him to marry her, so it balances out.
Different case! I specified that the woman was convinced the man was going to marry her, based on his promise. She felt no need to use sex to get anything. The woman presumably simply had sex with a man she thinks is about to marry her because she expects they both will enjoy it.
A woman having sex hoping to nab a man seems OK to me -- he is not giving up anything. If she swears she is using contraception when she isn't, that is bad.
so what was bad was the man's false promise, and if both enjoyed the actual sex and thought it was consensual and good then that's good.
The false promise might be not ideal, but when he takes action which he knows people very commonly view as restricted to committed relationships, that's when it gets much worse.
For your general comment, that bad interactions also include ones they later decide were bad; according to that logic any interaction could be bad at some time after it happened
I think that is completely correct. We haven't defined just what "bad" means here. But they can be bad based on what people knew or should have known at the time. The law allows for children's view of things that happened to them changing as they grow up, and even expects it.
Consider a man who offers a 4-year-old a shiny dime in exchange for a ratty-looking twenty-dollar bill. The child can at the time genuinely desire this exchange, but we expect that they will come to feel they were wronged within a few years. If an adult accepts the dime-for-a-twenty exchange, that's entirely their business.
Not all bad things should be illegal, as in these interactions between adults that are just very complicated.
I'm not arguing for any particular age of consent. Obviously it's tricky and God never said it's got to be 16 or 18 (or 14). I say leave it up to the teleios (ordinary folks) to sort it out.