Everyone knows children are capable of expressing opinions and giving consent. The question is whether an adult can rely on that consent to do mutually agreed activities without legal consequences.

There are arguments on this subject that it is easy to dismiss as being puritanical. The best ones lie within a reasonably sex-positive framework. For instance, in this framework there's nothing wrong with children masturbating or playing doctor with each other. There's no legal problem with peers who are close in age engaging in all sexual activities, though concern may be expressed about whether it's a good idea.

People, especially females, often experience a great deal of regret around sexual activity. The common argument here at GC is that this is all due to society's misguided attitude shaming them. The enlightened view opposes slut-shaming in any form, but still thinks regret would remain a common and legitimate reaction even if societal values loosened. This view does not want to change society's values so dramatically that sex with other people is only an action of the moment and taking into account emotional bonds or broader context is actively discouraged.

The danger of regret may be present at all ages, but in contrast the cost to refraining from all sexual activity (with others) rises dramatically with age. People want a sex life, and so society paints an arbitrary line (mostly around age 16 these days) where the benefits have a fair shot of exceeding the costs in regret. Rising social knowledge also means the chances of avoiding to-be-regretted situations go up.

Society is motivated to consider this a serious problem rather than an odd backwater because in fact a great many men are intensely interested in sexual activity with a broad range of partners, including post-pubescent minors (fewer of us with prepubescents). The legal position that the adults cannot trust the expressed consent of these minors protects many of them against situations with a high probability of regret and against indisputable rape.

In this enlightened view it has nothing to do with wanting to control young people or fear of their sexuality. On this view no one would prosecute a minor for taking or distributing a sexual selfie. The prohibition is motivated simply by best judgment as to what maximizes the long-term happiness of the minors involved. One way we can see this is that sex-positive people holding this position have no desire to punish minors who engage in sexual activity, only the adults. They would feel no need to bully the minors into evaluating a past sexual experience one way or the other, and would not prosecute adults without the freely chosen cooperation of the minor involved.

There is much to object to in the way society currently treats these situations, butthose excesses could be corrected and a moderate position would still say that adults cannot rely on children's consent in sexual matters.