Equivocation about the meaning of "adult"

[PorcelainLark]

"Adult" as legal/moral status versus as objective psychological development

Here's a thought experiment. Say that a person with an IQ of 85 had sexual relations with a child, would the average person say this is wrong? I think the answer would have to be yes. On what basis? That as an adult the person has a responsibility not to.
However, on the other hand, on what basis do we say a child shouldn't have sexual relations? That they are incapable of understanding the consequences of sex.
So, in the first case "adult" is just a formal status - it doesn't matter how low the intelligence of that person is, the fact they are 18 or older is all that matters; but in the second case, the claim is on the basis of lack of intelligence/understanding, some objective quality of the mind.
Neither horn of the dilemma is sufficient for the current attitude; either people of the same level understanding should be allowed to have sexual relations regardless of age, or the age of consent has nothing to do with a child's capacity to understand sex.

[Bookshelf]

I've found that everything is a simple roundabout way to justify the opinion; a minor cannot have sex. The opinion is formed first, and then logic is construed to support that, contrary to basing an opinion off of logic.

This is obvious when looking at the thought process behind categorical ages of consent - when, say, the 'age of consent' is 14, but only within a certain age group. Then they must wait until they are 18+ to open that up to anyone above that age range. The law and society around it will say that this 14 year old cannot understand the consequences of sex, unless it's with someone else of the same age. Two people not understanding the consequences of sex somehow cancels it out, I guess.

[Harlan]

However, on the other hand, on what basis do we say a child shouldn't have sexual relations? That they are incapable of understanding the consequences of sex.

What are these special consequences ? How are these consequences different from playing a console game or soccer ? It is a simple pleasant activity between people who respect and trust each other.

Does a minor understand the consequences of riding a bicycle, that he or she could get into an accident and be seriously injured ? Children on YouTube videos of skydiving were able to give informed consent, they understand that the parachute may not open and they may crash ? Why is there no harm from pediatricians touching children's genitals and anuses? Why could 13-year-old Magnus Carlsen play chess on equal terms with Garry Kasparov, but could not engage in mutual masturbation with him? If mutual masturbation of minors is considered harmless, then why does inter-age masturbation suddenly become harmful ?

What kind of trauma is this that adapts to society's fears ? Or maybe it is caused by these fears ?

the argument most omnivores give for the permissibility of eating animals is that they lack the same level of intelligence of humans.

Someone on BC mentioned someone's quote about moral paradox: "We allow ourselves to brutally kill animals, but we do not allow ourselves to gently fuck them".