I think the key word in this is "arbitrary." Frankly the ages we set for the things we do are, at least to some degree, arbitrary. When you start to justify the ages set, someone can justify another age quite easily. Older or younger, there are always reasons why the age chosen is the wrong one and another is the right one. We have, to some degree, arbitrarily chosen the age of consent many here are acting as if were absolute moral rules. They aren't, and the mind that acts as if they are is one that hasn't looked at them critically. The stage is set for subjective interpretation and the ethical slide - so, get ready for a ride when the immigrants we welcome with the intent to respect their culture say "why 18?" Their arguments will not be without reason backing them.
Sky high divorce rates suggest that our culture doesn't create people "mentally developed" enough for marriage well past the legal age and, in fact, that people may never be "mentally developed" or "mature" or whatever you want to call it. Hell, the evidence that the way we look at marriage is dysfunctional is staggering, and or notion of legal consent is so convoluted and at times contradictory that it becomes almost nonsensical - and we're sitting here patting each other on the back for how wrong some other culture has it. Again, cultural imperialism in action.
I could be a prick and start down the road of attacking the claim of "she's a child - she doesn't know what that means yet" and focus on the absurdity of the idea that, at 18, when our culture slams down its societal gavel and says "you can now consent," the mental children we are releasing into the world "know what it means." I've known fifteen year olds who likely have more claim to knowing "what it means" - concerning love - than some forty year olds. Again arbitrary is the key word - because many of the standards in question were set arbitrarily and devastating countercases could be leveled against them if we weren't so indoctrinated into thinking "This is the right way of doing it."
I think we both know that if we started down a path of the justification for the age of consent, our standards of who can get marriage, we'd find they're culturally rooted, to some degree arbitrarily chosen, and the basis for those ages and standards of marriage could be torn down in a reasonable manner. But, I'm not here to do that... Consider this a warning - we're all sitting here having our little 21s century Western values back patting session, a veritable echo chamber, laughing at the way this other culture does things, but the argument is coming. If you want things to stay the way they are, you had better hope that those posters that say "Love always wins" were wrong.
I've got work to do. Enjoy the echo chamber... Just don't delude yourself that because everyone here agrees with you, a group of largely Western World people indoctrinated into one cultural standard, that the world at large is going to do so as well. When you open your doors and actually attempt to respect their cultures, you'll hear the counter cases, and all of the sudden ideas like our set age of marriage, age of consent, etc, will be on the table.
