When you say that a person is considered a child as one under the age of 18, I assume this reflects the legality behind 'capacity'. Some places consider a child to be under the age of 12 or 16. I found the following definition stated by a judge here in Oz in relation to consent to perfectly describe the dilemma:

The person has to have a cognitive capacity to be able to consent. So you could have a
circumstance where a person might give free and voluntary consent but if they don't have the cognitive capacity to properly consent then it wouldn't be consent within the meaning of the law. Now a classic example of that might be someone who has an intellectual disability. A person who is intellectually impaired might very well say, "Yes, I'm prepared to engage in sexual intercourse," but lack the cognitive capacity to understand what they are doing…Under our Criminal Code, in relation to consent, the law provides that consent means consent freely and voluntarily given by a person with the cognitive capacity to give the consent. Cognitive capacity in that context means that at the time that the offence is alleged to have occurred, the complainant had sufficient understanding to know what was occurring in order to be able to give consent to it.

This is crucial in ascertaining that fine line between a minor consenting to a contract or sexual intercourse and their capacity to engage that may not essentially be a 'free agreement' especially if they do not have the cognition to be aware of what their actions, the consequences and a number of other factors would be should they agree. Active acquiescence is not consensual agreement and consent is not a defense in the case of sexual crimes. A person with an intellectual disability similarly does not have the capacity hence why there are guardianship laws and power of attorney etc.These laws that restrict decision-making rights to 18 are there to protect and I see nothing wrong with that, particularly in the case of contract law and sexual abuse or exploitation.

But, in my opinion, there can be another way of looking at it; by enabling a type of 'presumption of capacity' where instead of adopting the undermining paternalism that assumes automatically a minor is incapable of making decisions to instead see children as themselves having rights and responsibilities, to empower their capacity to exercise those rights. We afford this functional approach to adults, and so in the case of particular crimes that may involve minors, to allow a type of analysis of whether they understand the action (rather than through say a clinical approach) where an understanding of the consequences and the nature - cause and effect - of that action is assessed. This is termed as the functional approach to cognitive assessment of capacity. They are still legally a minor until they are 18, but afford a certainly flexibility so that should they consent to sexual intercourse at, say, aged 17 with a 20 year old who may possibly be convicted of statutory rape, can be assessed as having the capacity to make that decision.

Is it time we revised our traditional 18-years boundary between childhood and adulthood? — TheMadFool

Yes. I would set the boundary at 16 or 14. I think there is a lot of oppression by parents and society of young people in that age group, 14-18. And that's because young people are very dangerous to society. I think people should be allowed to drink and smoke from 14 for example.

There is no point living from 14 to 18 in a straightjacket, as if you weren't living in the real world anyway. People should also be allowed to work, and do so easily from 14, without tons of paperwork. In fact, work should be encouraged for this age group. There is no time to lose.

So, I wouldn't be wrong in saying children are maturing faster nowadays. Some under-18s even have their own business ventures and outdoing even more experienced adults. — TheMadFool

It's not that they are maturing faster. They've always matured faster, society just didn't acknowledge it. For example, my thinking at 14 wasn't much different than my thinking today. Sure, it was more raw and stuff, I had different opinions, etc. but fundamentally I'm as developed as I was back then in terms of pure, raw intelligence.

Is it right to restrict the autonomy of a mentally mature human being? — TheMadFool

No.

They are still legally a minor until they are 18, but afford a certainly flexibility so that should they consent to sexual intercourse at, say, aged 17 with a 20 year old who may possibly be convicted of statutory rape, can be assessed as having the capacity to make that decision. — TimeLine

I think I've seen several guys in their late teens or early 20s dating 14-16 year old girls over my life. So... I don't think that should count as rape if the girl consents and is okay with it. The law should be modified to take into account the fact that people above 14 can generally pretty much make decisions for themselves. In some countries, the laws already allow for this. I think in the UK one can give their consent with regards to sex if they are 16, or something similar. Can't remember for sure.

I think I've seen several guys in their late teens or early 20s dating 14-16 year old girls over my life. So... I don't think that should count as rape if the girl consents and is okay with it. — Agustino

It depends on the laws of your country, but one could be charged with statutory rape - such as if the parents of the girl make a case of it - and in the case of a minor, consent is not a defense for sexual crimes. Hence, why I initiated the discussion of cognitive capacity and not consent, to ascertain whether there is a free agreement there or whether it is merely acquiescence; comparatively, can those with intellectual disabilities be allowed to pursue a sexual relationship? For instance, there was a case here where a man had sexual intercourse with an intellectually disabled adult and he was charged - despite her consent - because she demonstrably lacked the capacity to understand the consequential aspects to sexual intercourse and accepted direction and dependency. He done other terrible things to her, but ultimately the judge stated that "whilst she did not resist in any way and may have even consented in some form or another, that consent was not a real or true consent because she was not mentally capable of giving her consent."

It depends on the laws of your country, but one could be charged with statutory rape - such as if the parents of the girl make a case of it - and in the case of a minor, consent is not a defense for sexual crimes. — TimeLine

Okay, but let's leave that to the side and discuss what the law ought to be, not what it is.

Hence, why I initiated the discussion of cognitive capacity and not consent, to ascertain whether there is a free agreement there or whether it is merely acquiescence — TimeLine

I think that 14-year-olds really do have sufficient cognitive capacity to consent to things. They're clearly capable to follow instructions at school, to make decisions about how to answer questions on tests, how to study, how to manage their free time, whether to play football, etc.

comparatively, can those with intellectual disabilities be allowed to pursue a sexual relationship? — TimeLine

I think they should be allowed if they seek this themselves. If they can pursue a sexual relationship that seems to tell us that their intellectual disabilities are not so severe that they don't understand what they're doing.

she demonstrably lacked the capacity to understand the consequential aspects to sexual intercourse — TimeLine

How is this demonstrably shown? Lawyers have lots of tips and tricks to "demonstrate" things which are actually never really demonstrated. And most people aren't very careful with their language unless they are trained philosophers, lawyers themselves, etc. It's relatively easy for a smart lawyer to get an uneducated person whom they're prosecuting to agree to whatever they want them to agree if they're smart. It's not so easy to capture or corner a philosopher on the other hand, who is one of the most slippery of creatures.

And if someone has intellectual disabilities, they clearly have even less control over the precision of their language, etc. So it's not difficult for a smart lawyer to get them to agree to anything - or to show that they're not capable to understand consequences, etc.

consent was not a real or true consent because she was not mentally capable of giving her consent — TimeLine

That may be true, but I think it's speculative. Maybe it should be illegal for someone to pursue a relationship with a mentally disabled person, but not the other way around, for the mentally disabled to pursue a sexual relationship with others.

I mean, the danger is that if you don't allow the mentally disabled to pursue sexual relationships, get married, etc. you're really cutting off their possibilities and abusing them. They become treated like some objects to be thrown around and obey what others ask them to, instead of free human beings. They end up more like prisoners in an Auschwitz like environment, where they're not allowed to reproduce, others get to decide for them etc.

You say:

How is this demonstrably shown? Lawyers have lots of tips and tricks to "demonstrate" things which are actually never really demonstrated. And most people aren't very careful with their language unless they are trained philosophers, lawyers themselves, etc. — Agustino

And then:

I think that 14-year-olds really do have sufficient cognitive capacity to consent to things. — Agustino

And:

If they can pursue a sexual relationship that seems to tell us that their intellectual disabilities are not so severe that they don't understand what they're doing. — Agustino

How can you demonstrate that they can?

How can you demonstrate that they can? — TimeLine

The first quote that you quote me as saying refers to what lawyers can demonstrate with regards to mentally disabled people. We don't know much about mentally disabled people, but we certainly know that their handle over language isn't that great.

How can you demonstrate that they can? — TimeLine

Their actions demonstrate it. I mean they solve quadratic equations at 14. Most people in history haven't been able to solve quadratic equations even at 40. These are clearly people who can follow a line of reasoning, understand consequences, and do things. They do it all the time at school, with their friends, etc. It's so obvious actually that I think it's ridiculous to think they lack cognitive capacity.

Think of yourself at 14. Do you honestly say that you lacked the cognitive capacity to understand what sex involved and the consequences?

I think I've seen several guys in their late teens or early 20s dating 14-16 year old girls over my life. So... I don't think that should count as rape if the girl consents and is okay with it. The law should be modified to take into account the fact that people above 14 can generally pretty much make decisions for themselves. In some countries, the laws already allow for this. I think in the UK one can give their consent with regards to sex if they are 16, or something similar. Can't remember for sure. — Agustino

Maturing is a process and works differently for everyone, I was sexually immature well into 21-22. I was mature in finances and could function without support from my parents when I was 17 (eating healthy, cooking myself, cleaning, work, study, locking doors etc.). I had the feeling most peers, especially girls, were sexually light years ahead of me.

At the same time, research in the Netherlands showed that 75% of women who consented to sex between the ages of 16 and 18 still regret it afterwards (when asked in their mid twenties). Those ages are socially acceptable and it's even more or less expected to happen then (a bit of peer pressure). Even though kids can make rational decisions (my 2.5 year old daughter manages at times!),that doesn't make children wise or capable enough to consider all the consequences.

Children, including teenagers, are more susceptible to developing addictions as well, which is another reason not to meddle with ages of consent especially where it concerns drugs (alcohol and cigarettes included).

The first quote that you quote me as saying refers to what lawyers can demonstrate with regards to mentally disabled people. We don't know much about mentally disabled people, but we certainly know that their handle over language isn't that great. — Agustino

We know a great deal about those with intellectual disabilities, but that is the difficulty of the nature of cognitive capacity vis-a-vis the law. If the court is satisfied that the woman in that particular case has an intellectual disability - including an IQ of 36 - completed in addition to a clinical assessment that verified that she was incapable of understanding the nature of her actions and that she was dependent and relied on the direction of others, all of which was known by the defendant who - as mentioned - did a number of other atrocious acts against her, then I agree with that decision. It was rape, there was no consent because it was not freely agreed upon since she did not understand the nature of the act.

As mentioned in my original post, the clinical approach does have limitations particularly relating to parameters that determine what something like 'understanding' actually is even if this diagnostic threshold has equitable validity, but the functional approach allows us to presume that a minor or a person with an intellectual disability has capacity rather than not. I hear whispers of this at the moment in the international domain regarding the covenant of the rights of children. By assuming capacity, a person is not locked in an immovable and patriarchal process, but it would give those who may have an intellectual disability or a highly intelligent or mature minor the opportunity to verify capacity by explaining and communicating choice together with retaining information as part of their decision-making process. This may cause some foreseeable issues in the broader side of things, but when there may be a crime or a guardianship decision, taking that strict paternalistic approach is too inflexible but taking the functional is also ambiguous. The criterion to determine 'understanding' or capacity is complex that it makes it easier to encompass incapacity to a particular age and again that is dependent on where you are from, 12, 16, 18 etc.

What I may be at 14 is irrelevant but honestly I had no clue at all about sex at that age, even though I was great at a number of intellectual pursuits that made me far more intelligent than people much older then me.

Think of yourself at 14. Do you honestly say that you lacked the cognitive capacity to understand what sex involved and the consequences? — Agustino

I am sorry but at age 14 even though I had the cognitive capacity to understand what sex involved, there is NO way that I could have EVER understood the lifelong consequences.
So much so that at age 15, my first was 23 and I thought I was in love forever. Now I see the difference between a lady at age 15 and the male interest at 23 was not healthy and never will be.

I was sexually immature well into 21-22 — Benkei

What do you mean "immature"?

I was mature in finances and could function without support from my parents when I was 17 (eating healthy, cooking myself, cleaning, work, study, locking doors etc.) — Benkei

Well, if you were mature at all those things, I really really can't see what you mean by the fact that you were immature when it came to sex, apart from things like you were laughing when you heard the word penis or something of that nature.

At the same time, research in the Netherlands showed that 75% of women who consented to sex between the ages of 16 and 18 still regret it afterwards (when asked in their mid twenties). — Benkei

I didn't say that people ought to have sex at that age, I just said that they should be allowed to decide on it.

Even though kids can make rational decisions (my 2.5 year old daughter manages at times!),that doesn't make children wise or capable enough to consider all the consequences. — Benkei

Nobody is wise enough to consider all consequences. That's just a fact of life. People need to deal with it though. It's part of learning.

Children, including teenagers, are more susceptible to developing addictions as well, which is another reason not to meddle with ages of consent especially where it concerns drugs (alcohol and cigarettes included). — Benkei

Right, so they need to be educated on those subjects too. But the right education involves both theory and practice.

I didn't say that people ought to have sex at that age, I just said that they should be allowed to decide on it. — Agustino

So if I was your daughter at age 15 and you saw a 23 yr old man courting me, would you condone our relationship?

What I may be at 14 is irrelevant but honestly I had no clue at all about sex at that age, even though I was great at a number of intellectual pursuits that made me far more intelligent than people much older then me. — TimeLine

That's because you didn't direct your intelligence towards understanding it, not because you lacked the cognitive capacity to understand it.

I am sorry but at age 14 even though I had the cognitive capacity to understand what sex involved, there is NO way that I could have EVER understood the lifelong consequences. — ArguingWAristotleTiff

Nobody can really understand consequences though. When I started my business, you think I understood consequences of all that I was doing? No, I was clueless about so many things. I learned along the way, and there are still many things I'm clueless about. That's just the nature of the beast. Nobody, except very very few people, are wise. The challenge in life is to learn how to make do with the little that you do have in terms of knowledge and understanding.

So if I was your daughter at age 15 and you saw a 23 yr old man courting me, would you condone our relationship? — ArguingWAristotleTiff

Well, it depends on who the 23-year-old man was, whether he obeyed what I told him and showed that he bought into my own ideal of having a large family, and wanted to marry my daughter, not just date her. I would also want him to be religious or otherwise convert to Christianity.

My ideal is to have a large family with all members being involved in the same work over time. I dislike the ideal of the nuclear family that is prevalent today, since it is destructive to the stability and strength of individuals. It actually weakens everyone, both the family, which loses the strength of the children, and the children, which lose the support and the wisdom of the family.

That's because you didn't direct your intelligence towards understanding it, not because you lacked the cognitive capacity to understand it. — Agustino

I did lack the capacity at that moment in time because I was dependent on others and had very little understanding of consequences. Most of us have the capacity but only when we surpass a certain age. Nevertheless, I understand you and I agree; that is why I am telling you that I support the functional approach, which can determine whether the child understands the action and the consequences of that action. There is current talks as mentioned in the international arena on children' rights and that we should stop taking that 'they are a child and therefore don't know any better' paternalism because we fail them in someway as individuals. We should learn - though ambiguous - to adopt an approach that identifies their capacity rather than simply assume them to be incapable

Ages of consent have never been stagnant and have varied by jurusdiction.

Sexual consent in the South was 14 in some states, then raised to 16. Some are 17, others 18. As the South began to raise its age, the North and Europe began to drop theirs.

You can join the military in the US at 18, but not drink until 21. France and Germany have younger drinking ages while the UK's is higher I believe. When I was young, you couldn't smoke until 16, now it's 18.

The point being these things are and have been in flux, typically evolving toward denying adulthood to later ages.

I disagree with the OP that kids mature faster now. A 12 year old in the 1800s probably had far more responsibility and lack of protection from the harsh realities of life than today's youth. More advanced societies require extended childhoods.

My generation was far less tended to than the current one, which is the result of it becoming more difficult to succeed today than before. An active parent can make a much bigger difference today than before, which results in children staying dependent longer. That is to say, if kids are so mature and independent, why do they stay in their parents's basement into their 20s?

I did lack the capacity at that moment in time because I was dependent on others and had very little understanding of consequences — TimeLine

What does being dependent on others (we're always dependent on others to some extent, btw) have to do with lacking cognitive capacity?

And with regards to having very little understanding of consequences... in what ways did that show? I mean if you could solve quadratic equations, follow directions at school, not put your hand in the fire, etc. it seems to me that you did understand consequences more than well enough. Could you follow the train of thought of the likes of Nietzsche, etc.? That shows to me great cognitive capacity already.

Time for a small anecdote. When I was around 13 I saw two guys indecently touching a girl around the toilet, who was telling them to stop, so I shouted at them, and when they heard they all ran away, including the girl. Naturally, after that I had an interesting story to tell, which I told other people around the school, and soon the news spread. Suddenly one day the principal came in class and picked me out of there, and said "given your actions, I don't think you should really be in our school anymore" and he took me in a room alone with himself, questioning me on what I had done. Instinctively, I knew to be as vague as possible, and give as few clear answers as possible. So he got tired of interrogating and threatening me at one point, and brought the girl and the two guys in the room. That's when I first realised what this was all about. Then they started to say - all of them, even the girl (probably cause she was embarrassed) - that I started spreading false rumours about them through the school about this and that. So I was very angry at that point, but I instinctively understood that I had to lie to escape, since there was no possibility of convincing the principle that two guys actually tried to rape the girl in school, when even the girl wasn't admitting to it. I also knew I had my youth on my side, so if I only apologised and admitted to fabricating the whole thing, even if it was true, I would be let go of. So I said that I was very stupid, that I thought it would be a funny joke, that I'm dearly sorry and will never do a similar thing in my life, basically begging everyone to forgive me. My aim was to (1) not be expelled, and (2) avoid getting the principal to contact my parents. And I succeeded. If I had chosen a different strategy, my life would probably have been very different today.

So clearly at that young age, I already had the political acumen to realistically understand my situation, and in a few minutes sketch out and execute a set of moves that allowed me to obtain my objectives. And I also understood that a little bit of humiliation was nothing compared to the other consequences -
as the Chinese say, even the great General Huan Xin had to crawl between the legs of two vagabonds. So I see evidence that quite the contrary, I was extremely cognitively capable at even 13.

Nevertheless, I understand you and I agree; that is why I am telling you that I support the functional approach, which can determine whether the child understands the action and the consequences of that action. There is current talks as mentioned in the international arena on children' rights and that we should stop taking that 'they are a child and therefore don't know any better' paternalism because we fail them in someway as individuals. We should learn - though ambiguous - to adopt an approach that identifies their capacity rather than simply assume them to be incapable — TimeLine

Okay, I see.

Time for a small anecdote. When I was around 13 I saw two guys indecently touching a girl around the toilet, who was telling them to stop, so I shouted at them, and when they heard they all ran away, including the girl. Naturally, after that I had an interesting story to tell, which I told other people around the school, and soon the news spread. Suddenly one day the principal came in class and picked me out of there, and said "given your actions, I don't think you should really be in our school anymore" and he took me in a room alone with himself, questioning me on what I had done. Instinctively, I knew to be as vague as possible, and give as few clear answers as possible. So he got tired of interrogating and threatening me at one point, and brought the girl and the two guys in the room. That's when I first realised what this was all about. Then they started to say - all of them, even the girl (probably cause she was embarrassed) - that I started spreading false rumours about them through the school about this and that. So I was very angry at that point, but I instinctively understood that I had to lie to escape, since there was no possibility of convincing the principle that two guys actually tried to rape the girl in school, when even the girl wasn't admitting to it. I also knew I had my youth on my side, so if I only apologised and admitted to fabricating the whole thing, even if it was true, I would be let go of. So I said that I was very stupid, that I thought it would be a funny joke, that I'm dearly sorry and will never do a similar thing in my life, basically begging everyone to forgive me. My aim was to (1) not be expelled, and (2) avoid getting the principal to contact my parents. And I succeeded. If I had chosen a different strategy, my life would probably have been very different today. — Agustino

Respect to you Agustino and may you feel secure in Karma taking care of the others.

That is to say, if kids are so mature and independent, why do they stay in their parents's basement into their 20s? — Hanover

What does one have to do with the other? If you're independent you should go live in the forest all alone to prove it, or what? :s That seems more of an ego thing than anything realistic.

If someone is mature and independent, they're not trying to prove things to anyone. As for why kids stay in their parents' home into their 20s, it may be because they don't want to pay rent, or they haven't found another place, or there really is no benefit to moving out, or they just don't have any initiative and are lazy.

Regardless of whether people live with their parents or not (there's nothing wrong living with your parents even into your 30s if the place is big enough, and your parents are okay with you coming or living with a girl home, etc.), they should make themselves useful. That means they should do the dishes, help with cleaning, contribute to paying the bills, maybe contribute to money parents need for medication, etc.

If you have a kid who lives at home with you the parent, but he's not doing any of these, and is a lazy sloth, then you do indeed have a problem. Sending him to the forest may or may not be the best way to resolve the issue. But the problem is that they are lazy and slothful, not that they're living with you.

This idea of parents pushing kids out of the home is actually extremely destructive to both themselves and the kids - it weakens the family. The parents lose the youth and strength of the kids, and the kids lose the wisdom of the parents. By weakening the family, both parents and children are more easily controlled by other forces of society.

I should also add that from my experience, it is the most immature that want to move out of their parents' home quickly, so that they can be free to do drugs if they want to, etc.

One thing I learned from Indian people I've met, is the importance and strength of an extended family. I almost couldn't believe some of the things I heard from those people. And when I talked to them, I realised that that's the kind of family I want to have for myself and my kids, and that the way we do things over here in the West is actually harmful.

My point is that extended childhoods are typical in advanced societies as are laws protecting children from sexual and economic abuses. Child labor laws are a protection, not an impediment. Delayed independence from moving from home is an additional symptom in the West of further extension of childhood. I don't suggest young adults be pushed into the world prior to being prepared, largely because I buy into this model.

As you would expect, however, if children are going to extend their dependence economically, you will liklely see laws reflective of that reality that keep them to some extent disenfranchised.

In other words, I disagree with the OP that today's youth are earlier equipped for adulthood than yesterday's.

My point is that extended childhoods are typical in advanced societies as are laws protecting children from sexual and economic abuses. — Hanover

Yes, I do notice that, but there's no necessity for it. Part of that, seems to me, to be due to the parents. The parents encourage the child to keep being a child, usually for far too long. They do that since they generally can provide for the child for longer. That means that they're not willing to let the child hold responsibilities, and treat him or her like a child. As a result of that, the child goes on to perceive him/herself as a child.

The parents also have another "defect" in my opinion. They outsource the education of the children to society for the most part, which I believe is a great mistake. I was lucky to have managed to find myself in the right circumstances which allowed me to educate myself. Had I not educated myself through vast reading and study, I would have likely been an idiot today. My parents could have prevented that had they assumed some sort of responsibility for educating me - apart from sending me to school, teaching me manners, and checking that I had good grades. I learned precious little in school that was relevant to life actually. University was more useful though.

Child labor laws are a protection, not an impediment — Hanover

Okay, but I view that as a problem. I think the child should start working as soon as possible. I don't really see any value in an extended childhood, but quite the contrary, you're delaying the time it takes someone to become an active participant in the world and its affairs. I don't understand why you'd want to do that.

As you would expect, however, if children are going to extend their dependence economically, you will liklely see laws reflective of that reality that keep them to some extent disenfranchised. — Hanover

Yeah, but that's precisely the problem. I think children need to be given responsibility from early on, and the family should try to integrate them in whatever the family is doing. If the father is a doctor, for example, he should take the kids with him to hospital, and start teaching them the very basics while they watch him. One of the kids may show an interest in it, in which case the father can start preparing him to be a doctor. And so on.

In other words, I disagree with the OP that today's youth are earlier equipped for adulthood than yesterday's. — Hanover

They are equipped, they're just not willing to use the equipment they have. If you have a university graduate, for example, sitting in his parents' basement and smoking weed all day with his friends while playing video games, you can't really tell me that you have someone who isn't equipped. They are amply equipped, it's just that they're not willing to apply their intelligence to a profession, or to making money, or something productive. That they are intelligent and capable is amply illustrated by the fact that they completed schooling and higher education in that case. What they lack is the adequate moral education and discipline, which parents did not give them because they always treated them like a child.

The ability to make goals for oneself, and make plans to reach those goals is extremely important, and it is parents that must foster it in children. School just stuffs a bunch of information in your head and carries everyone along - but they don't make people independent, nor help them think for themselves.

The laws that protect children do not ascribe them some special degree of protection. It is illegal to assault an adult, it is illegal to become violent and damage property if drunk. We educate adults about the risks of smoking, etc. So what we're really doing in most of the legal ages we set is presuming the child will fail. We cannot allow them to drink because they will probably fail and get too drunk, we cannot let them vote because they'll fail and vote for someone stupid, we cannot let them have sexual relationships because they'll fail and pick partners who they later regret.

Tell someone that they're so useless at making decisions that we have to actually ban them legally from doing so for the first 18 years of their life and you end up with the disaffected generation we have nowadays.

The situation in the 21st century has changed dramatically. With an unprecedented access to information through media (magazines, books, tv and the interent) children of this generation are more informed than their predecessors and this trend is only going to increase.

So, I wouldn't be wrong in saying children are maturing faster nowadays. Some under-18s even have their own business ventures and outdoing even more experienced adults. — TheMadFool

I came late to this discussion, so I don't really know how to catch up, so I'll start out laying out my general understanding.

Maturity doesn't have much to do with knowledge. Maybe nothing. It's not that children are more ignorant or less experienced than adults. Their brains are different. They're not mature because their minds have not developed cognitively to the point where they understand the consequences of their actions on themselves and others.

Family dynamics also has a big effect. In the society where I live, young people, even those who might be mature cognitively, are not given the chance to gain the experience they need to live safely on their own. You can say we should change that. Well, ok, but that's easier said than done. A lot of kids would get trampled in the transition.

Young children are vulnerable. They don't have the resources to protect themselves from the world or other people. They need to be protected. Here's the image I see when I think of this. The child lives inside a metaphorical fenced area put up by her parents. When she is a baby, the fence is very close. As she get's older, she starts to move around and eventually starts bouncing against the fence. At some point, the parents expand the fenced area to allow the child more freedom. This continues until the child is old enough to take care of itself. I recognize that this is an result of the fact that I live in an affluent society that can afford to provide that level of protection.

At what age do we draw the line between childhood and adulthood? Based on my experience in my own particular community, I'd say probably 15 or 16. Definitely not 14. That doesn't mean kids can't start to take more responsibility or have more freedom sooner, but up to whatever age we choose, the child's will is vested in the parents. When things go right, the parents and children work out a good balance of restrictions vs. responsibility.

Although it's certainly not always true, I think parents are generally more likely to protect their children and take their interests to heart than any other people or institutions I can think of. It is appropriate that our laws reflect that.

This definition has to do with mental maturity - those who're less than 18 considered unable to think for themselves. This was fine because prior to the 21st century people under 18 were clearly immature and thus the restriction on their autonomy was justified. — TheMadFool

It isn't that people younger than 18 are "considered unable to think for themselves". Clearly many people younger than 18 or 17 or 16 can "think for themselves". What they can't do is assume certain "adult" responsibilities. This is a matter of legislated law, not child development. Some 45 year olds, of sound mind and normal intelligence, don't do a good job of accepting "adult" responsibilities. Some 15 year olds do.

The situation in the 21st century has changed dramatically. With an unprecedented access to information through media (magazines, books, tv and the interent) children of this generation are more informed than their predecessors and this trend is only going to increase. — TheMadFool

People -- all ages -- have access to vast quantities of information, some of which they did not have access even 20 years ago. However, "having access to a huge library" isn't the same as actually reading a book or a report. Picking up the book and reading it isn't the same as actually understanding the book, and being able to make use of it. It is an error to assume that this generation is more informed than their predecessors, for a couple of reasons:

What people in the mediated world of today are familiar with, know, and understand is -- as it has been for a long time -- spotty. 25% of 18 year olds today may have a high level of knowledge about media, but know very little about global warming. They may have performed well in high school mathematics classes, but know nothing about money management. They may have paid attention in class, learned grammar and punctuation, read all the required and option reading in English classes -- and not know how to fix a leaky faucet, or understand how their own body works.

So, I wouldn't be wrong in saying children are maturing faster nowadays. — TheMadFool

Yes you would be.

A child's brain does not mature faster today than it did 100 or 200 or 2000 years ago. The brain doesn't finish maturing until about age 25. One of the reasons why the teen age years are characterized by often exasperating behavior is due to changes in their brains, as well as changes in their hormones.

In centuries past, children were, in a way, viewed as miniature adults. Expectations of children were considerably more stringent than the expectations of children today. For instance, a 13 year old girl might be considered old enough -- and ready -- to marry and bear children; in many cases they were married off early. This was probably an all round bad experience for the young person, but that's the way life was, and one coped.

We know more about children today than we did in the past. Yes, children often learn given blocks of material earlier than they did in the past, but that is largely because expectations among parents and teachers are higher now than it was, say... 50 years ago. Children and adults still function about the same as always, but what is deemed suitable has changed.

As note by other posters, there is a lot of variance among people in how fast various skills develop, or when traits appear. This is true now, and it was true in the past. Some 15 year olds may be ready to engage in independent sexual relationships (not chaperoned) while some 24 year olds may not be ready yet.

These laws that restrict decision-making rights to 18 are there to protect and I see nothing wrong with that, particularly in the case of contract law and sexual abuse or exploitation. — TimeLine

That's the main point I guess. We need to facilitate and protect. Generally under-18s need more of the latter. It makes sense

But, in my opinion, there can be another way of looking at it; by enabling a type of 'presumption of capacity' where instead of adopting the undermining paternalism that assumes automatically a minor is incapable of making decisions to instead see children as themselves having rights and responsibilities, to empower their capacity to exercise those rights. — TimeLine

It's good to give under-18s more autonomy to allow them early access to the benefits of the adult world but we also need to avoid the obvious pitfall of exploitation by unscrupulous adults. I guess we must err on the side of caution.

And that's because young people are very dangerous to society. — Agustino

I think quite the opposite. Many elements of adult society are dangerous for youth. As I said in my reply to TimeLine above the need to protect outweighs the advantages of greater autonomy at a younger age. What do you think?

It's not that they are maturing faster. They've always matured faster, society just didn't acknowledge it. — Agustino

Maturity requires experience and with modern media children have access to, literally, billions of second-hand experience of others. Don't you think this affects the maturing process of minds? For instance a 12 year old in New York is definitely more mentally advanced than a 12 year old Ghanian villager.

I disagree with the OP that kids mature faster now. A 12 year old in the 1800s probably had far more responsibility and lack of protection from the harsh realities of life than today's youth. More advanced societies require extended childhoods. — Hanover

Mental maturity in terms of knowledge on how the world turns is possible at a younger age now than it was before. The media bombards children with information and this surely has an effect on the mind.

I agree that children in the past had ''responsibilities'' but they were of such kind that didn't affect their mental maturity. Farming and fetching water don't do anything for the mind but seeing the president give a complex point of view on TV does.

This is a matter of legislated law, not child development. — Bitter Crank

The law must have some basis and what better than biology to legislate? May be I'm being myopic in that moral ''ought'' doesn't have to match the ''is''.

Young children are vulnerable. — T Clark

That's the key issue as I said in my reply to TimeLine.