In western cute culture today, the word abuse has virtually become synonymous with the word harm. The way it is used now, sexual abuse might as well be called sexual harm. But, and this might seem out of left field to some of you, that is not a proper understanding of the word abuse. To be sure, abuse can, and does, cause tremendous harm, and we should do everything we can to prevent it, but it isn't itself synonymous with harm (I would maintain that all legitimate abuse is harmful even if it is not immediately evident). If it were true that abuse and harm were synonymous, then all one would have to do to escape the accusation of sexual abuse is to show that the other person has not been (noticeably) harmed. No harm = no abuse. Really? You might say, "what's wrong with that? It makes perfect sense to me." But there is a very important question here that immediately arises if we adopt that paradigm: who determines what constitutes harm? That throws the whole discussion into the realm of subjective opinion. Groups that lobby for the right of adults to engage in sexual acts with minors are making precisely that argument--that what they are doing does not cause harm (yes, these groups really exist, see nambla.org). Richard Dawkins, the famous atheist biologist, got in a lot of trouble a couple of years ago when he said that "mild pedophilia" does not cause any lasting harm. (http://www.huffingtonpost.com/2013/09/09/richard-dawkins-pedophilia_n_3895514.html). Now, if a judge somewhere determines that they are right, and hands down an opinion that certain forms of pedophilia are not harmful, are you prepared to say then that it is not child abuse? I would wager that most people would say no. And that is because we know, intuitively, there is something more fundamental to what makes something abuse than simply how much harm it causes. While abuse causes tremendous harm, equating abuse with harm leads to a very dangerous place.
So then, what is the proper meaning of the word abuse? It is really quite simple. It means to misuse. That is precisely what the etymology of the word indicates. Coming from the Latin combination of ab, meaning away, and uti, to use, it literally means to use in a way that deviates away from the proper use. But that understanding has important implications. Namely, in order for there to be abuse, there must be a an intended or proper use. If there is no purpose, or intended use for a thing, then it cannot, by definition, be misused. That includes human sexuality. Interestingly, our culture today is trying to insist that there is no intended use for human sexuality. Instead sexuality is entirely open to one's own freedom of interpretation and expression. If it makes you happy, and doesn't harm anyone (notice again the condition: no harm), then it is good. I hope you can see that such an ethic necessarily eliminates the possibility of abuse. If there is no intended use for human sexuality, then there can be no misuse. And if there can be no misuse, there, by definition, cannot be abuse. Sure, there can still be sexual harm, and we all agree (for now) that we should punish that. Of course, as I said before, that leaves us totally into the realm of subjective opinion. It is then left up to a judge to determine if harm was done, and since the definition of harm, like so many concepts, is likely to evolve over time, who can really say what is right or wrong in such cases? It just comes down to a matter of one person's opinion over another's. Does the judge think the act in question was harmful? In such a reality (and that's where we are headed once we adopt a "no design for sexuality" ethic) I'd hate to be the parent of a child who had been sexually abused, only to be told by a judge that there was no real harm done, they love each other, and the perpetrator was free to go, and free to continue his/her relationship with my child.
Some people will immediately roll their eyes at such an example. But please, PLEASE, tell me what about it is unrealistic. And don't give me the, "Oh, come on, everyone agrees that there must be consent between two adults, otherwise it's harmful," line. Based on what standard? Who is everyone? The folks lobbying for adult/child love don't agree. Richard Dawkins, famous for being brighter than most of us, doesn't agree. Even supposing that "everyone" agrees on that today, who is to say that the next generation will agree? According to Dawkins, "you can't condemn people of an earlier era by the standards of ours" (http://www.huffingtonpost.com/2013/09/09/richard-dawkins-pedophilia_n_3895514.html). If you can't judge the actions of one generation by the standards of another, who then is to say that what is unthinkable in this generation will not be normal in the next? More importantly, the whole "everyone agrees" concept is simply an appeal to conventionalism--whatever most people think is right is right. But conventionalism is intuitively false, as it eliminates the possibility of reform and/or progress. If the majority (aka everyone) thinks something is right, then any minority that would push against that thing is wrong. You couldn't ever be justified in challenging the status quo. Again, we intuitively know that is absurd. Martin Luther King Jr wasn't wrong because he was in the minority. And he didn't gradually become more right as he persuaded people to his position. Rather, he was right, even in the face of opposition, because he appealed to a transcendent standard of human rights, an unchanging standard that has to do with the purpose for which we were made, "all men are created equal." But if there is no design for human kind, no purpose, or standard for how we ought to treat one another, then Dr. King was, at most, lobbying for his opinion over the opinion of others. Once again, we know that is ridiculous. He was appealing to the way things OUGHT to be--and that requires an objective purpose/design for things.
In short my point is this: if there is no intended use for a thing, there can be no abuse for that thing. But if there is an intended use, then anything that deviates from that is, by definition, abuse. The same applies to human sexuality, and while no one would openly say "I support sexual abuse," in a lot of cases, that is only because they have wrongly equated abuse with harm. Many of the same people would happily agree "human sexuality is whatever you make it, just don't hurt anyone." And they think they have taken the moral high ground by doing so. The problem is that by stripping human sexuality of any intended purpose, they unknowingly do away with the true concept of sexual abuse altogether (deviating from the intended purpose of a thing), and push everything into the realm of one opinion vs another. Is X harmful? A lot of people say it's not. Okay, cool, then it isn't abuse. Really? In the best case scenario (for those who would say that), they are right, it isn't harmful, and since there is no intended purpose, there is no abuse. In the worst case, they are wrong, and they are tolerating, perhaps even celebrating a many legitimate abuses--and legitimate abuse is always harmful, even if it is not always immediately evident.