# Why is 18 considered when you become an adult? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 9, 2013, 2:21pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507 "2013-11-09T14:21:23Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Aquadementia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aquadementia/32/555_2.png) [@Aquadementia](https://boards.straightdope.com/u/Aquadementia)\ **Post date:** [November 10, 2013, 3:25pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/21 "2013-11-10T15:25:10Z")
> [@DrFidelius](#): > > Details. The government could have cobbled up a “maturity test” if they felt the need, similar in the way that “intelligence tests” were used for years to exclude certain classes of immigrants. Creating such a test sounds like an impossibility. You come up with even a single question for a test like that. If virtually no 10 year old should be considered mature, but most every 18 year olds should be, given that a test exist there would practically be no 10 year old that couldn’t study or be coached to pass that test. Yet a 10 year old is still a 10 year old and will behave like a 10 year old. You may have better luck testing something physical, like how much weight they can lift, if you want that to be the definition for maturity. There is practically nothing you can define as adult that a child can’t mimic if pressed, but probably shouldn’t be. Child labor laws weren’t made and all their work given to adults because kids were doing a bad job. It was so kids have a chance to develop. ---
**Author:** ![WilyQuixote](https://avatars.discourse-cdn.com/v4/letter/w/f9ae1b/32.png) [@WilyQuixote](https://boards.straightdope.com/u/WilyQuixote)\ **Post date:** [November 10, 2013, 4:01pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/22 "2013-11-10T16:01:25Z")
In this hypothetical world of “maturity tests” what would happen to those above 18 (or 21, or whatever) that are unable to pass this test? Would they remain minors indefinitely? ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [November 10, 2013, 4:06pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/23 "2013-11-10T16:06:09Z")
I dunno, maybe we could base it on [personal experience](http://www.smbc-comics.com/?id=3141#comic). ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [November 10, 2013, 4:36pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/24 "2013-11-10T16:36:23Z")
> [@don\_t\_ask](#): > > Because in most places the younger ages have been shotgunned by [the age of consent.](http://en.wikipedia.org/wiki/Ages_of_consent_in_North_America) Part of it is that the entertainment industry has sort of ingrained the 18 year old age of consent into the culture because that’s what it is in California, even though it is younger in most other states. ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [November 10, 2013, 4:43pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/25 "2013-11-10T16:43:44Z")
> [@WilyQuixote](#): > > In this hypothetical world of “maturity tests” what would happen to those above 18 (or 21, or whatever) that are unable to pass this test? Would they remain minors indefinitely? Yup. Unless they served in a military or equivalent position and earned their citizenship. Maybe we could make a movie about it. With co-ed showers. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [November 11, 2013, 1:24am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/26 "2013-11-11T01:24:40Z")
> [@WilyQuixote](#): > > In this hypothetical world of “maturity tests” what would happen to those above 18 (or 21, or whatever) that are unable to pass this test? Would they remain minors indefinitely? In my version of said world, that would be impossible unless you were mentally ill. The maturity being tested would be about how your brain processes information. There is a marked difference between how a teenager and adult process things. And that difference is the only reason I can rationally justify age of consent at all. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [November 11, 2013, 1:43am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/27 "2013-11-11T01:43:16Z")
> [@DCnDC](#): > > Why is 18 “random” but 13 or 20 makes sense?! Tradition! ---
**Author:** ![bienville](https://avatars.discourse-cdn.com/v4/letter/b/4bbf92/32.png) [@bienville](https://boards.straightdope.com/u/bienville)\ **Post date:** [November 11, 2013, 2:37am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/28 "2013-11-11T02:37:33Z")
> [@Ethilrist](#): > > Tradition! At three, I started Hebrew school. At ten, I learned a trade. I hear they’ve picked a bride for me. I hope she’s pretty. ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [November 11, 2013, 3:02am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/29 "2013-11-11T03:02:25Z")
You have to draw the line somewhere. 18 is largely it. If enough people decide it should be considered a different age, then it will be. ---
**Author:** ![DevilMayhem666](https://avatars.discourse-cdn.com/v4/letter/d/258eb7/32.png) [@DevilMayhem666](https://boards.straightdope.com/u/DevilMayhem666)\ **Post date:** [November 24, 2013, 12:36am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/30 "2013-11-24T00:36:22Z")
I was wondering this myself. What is the history behind it being 18 on average? ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [November 24, 2013, 2:21am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/31 "2013-11-24T02:21:23Z")
> [@DrFidelius](#): > > Yup. Unless they served in a military or equivalent position and earned their citizenship. Maybe we could make a movie about it. With co-ed showers. Remember, service guarantees citizenship. ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [November 24, 2013, 2:30am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/32 "2013-11-24T02:30:52Z")
> [@BigT](#): > > In my version of said world, that would be impossible unless you were mentally ill. The maturity being tested would be about how your brain processes information. There is a marked difference between how a teenager and adult process things… Are there any “tests” as the term “test” is commonly defined that are generally believed to test for this with any reasonable validity? Are we going to use IQ tests? One could imagine that the “maturity test” would actually consist of interviews with psychiatrists, teachers, etc., with a final “professional judgment” determination of maturity. E.g. there would be no paper-and-pencil (or online, etc.) “test” that you could register for and just answer the questions, you would have to be formally evaluated by a psychiatrist who could make whatever diagnoses he thought you had, etc. If we wanted a traditional written test, would the questions be knowledge and reasoning based (e.g. “List three ways that the Federal budget could be balanced.”) or would they be opinion questions where the real goal is to see whether or not society agrees with your judgement (e.g. “How would _you_ balance the Federal budget?”, and answers that propose a 70% income tax or abolition of the military are automatically stamped “Immature”)? ---
**Author:** ![DevilMayhem666](https://avatars.discourse-cdn.com/v4/letter/d/258eb7/32.png) [@DevilMayhem666](https://boards.straightdope.com/u/DevilMayhem666)\ **Post date:** [November 24, 2013, 4:47am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/33 "2013-11-24T04:47:36Z")
> [@BigT](#): > > In my version of said world, that would be impossible unless you were mentally ill. The maturity being tested would be about how your brain processes information. There is a marked difference between how a teenager and adult process things. > > And that difference is the only reason I can rationally justify age of consent at all. From what I’ve read teens around 15 or 16 are not intelligently different as IQs reaches maturity around that time. Rather that they are emotionally different. > [@](#): > > WASHINGTON—A 16-year-old might be quite capable of making an informed decision about whether to end a pregnancy - a decision likely to be made after due consideration and consultation with an adult - but this same adolescent may not possess the maturity to be held to adult levels of responsibility if she commits a violent crime, according to new research into adolescent psychological development. > “Adolescents likely possess the necessary intellectual skills to make informed choices about terminating a pregnancy but may lack the social and emotional maturity to control impulses, resist peer pressure and fully appreciate the riskiness of dangerous decisions,” said Laurence Steinberg, PhD, a professor of developmental psychology at Temple University and lead author of the study. “This immaturity mitigates their criminal responsibility.” > > The findings appear in the October issue of American Psychologist, published by the American Psychological Association. > > Steinberg and his co-authors address this seeming contradiction in a study showing that cognitive and emotional abilities mature at different rates. They recruited 935 10- to 30- year-olds to examine age differences in a variety of cognitive and psychosocial capacities. > > The participants took different tests measuring psychosocial maturity and cognitive ability to examine age patterns in numerous factors that affect judgment and decision-making. The maturity measures included tests of impulse control, sensation-seeking, resistance to peer influence, future orientation and risk perception. The cognitive battery included measures of basic intellectual abilities. > > There were no differences among the youngest four age groups (10-11, 12-13, 14-15 and 16-17) on the measures of psychosocial maturity. But significant differences in maturity, favoring adults, were found between the 16- to 17-year-olds and those 22 years and older, and between the 18- to 21-year-olds and those 26 and older. Results were the same for males and females, the authors said. > > “It is very difficult for a 16-year-old to resist peer pressure in a heated, volatile situation,” Steinberg said. “Most times, there is no time to talk to an adult to inject some reason and reality to the situation. Many crimes committed by adolescents are done in groups with other teens and are not premeditated.” > > In contrast, differences in cognitive capacity measures increased from ages 11 to 16 and then showed no improvements after age 16 - exactly the opposite of the pattern found on the psychosocial measures. Certain cognitive abilities, such as the ability to reason logically, reach adult levels long before psychosocial maturity is attained, Steinberg said. > > “Medical decisions are those where adolescents can take the time to understand and weigh options provided by health care practitioners,” said Steinberg. “Rarely are these decisions made in the heat of the moment without consultation with adults. Under these circumstances, adolescents exhibit adult maturity.” > > Two friend-of-the-court briefs filed by APA in cases heard by the Supreme Court spurred questions about these maturity differences and the apparent inconsistency between APA’s positions in the two cases. In its amicus brief filed in Roper v. Simmons (2005), the case that abolished the juvenile death penalty, APA presented research showing that adolescents are developmentally immature in ways that are relevant to their criminal culpability. In an earlier brief filed in Hodgson v. Minnesota (1990), which upheld adolescents’ right to seek an abortion without parental approval, APA presented research regarding cognitive abilities that bear on medical choices, showing that adolescents are as mature as adults. > > APA differentiated these two scenarios by looking at the decision-making processes required for each situation. In the Hodgson case, APA described adolescents as being competent to make informed and sound health care decisions. In the Roper case, APA characterized adolescents as too short-sighted and impulsive to warrant capital punishment, no matter what the crime. APA placed the research about psychosocial development of adolescents in the context of a court’s need to determine as part of a death penalty sentence that the perpetrator can reliably be assessed as among the “worst of the worst.” > > In November, the Supreme Court is slated to hear two cases concerning the constitutionality of sentencing juveniles to life without the possibility of parole. “Similar questions about adolescent development may be raised in these cases,” Steinberg said. APA has filed an amicus curiae brief in those cases presenting relevant research, including Steinberg’s most recent study, to the court. > > Adolescents’ legal rights, said Steinberg, should be guided by accurate and timely scientific evidence on the nature and course of psychological development. “It is crucial to understand that brain systems responsible for logical reasoning and basic information processing mature earlier than systems responsible for self-regulation and the coordination of emotion and thinking,” he said. > **[While adolescents may reason as well as adults, their emotional maturity...](https://www.apa.org/news/press/releases/2009/10/teen-maturity)** > > Adolescents possess the intellectual skills to make informed choices, but lack the social and emotional maturity to control impulses, resist peer pressure and fully appreciate the riskiness of dangerous decisions. ---
**Author:** ![DevilMayhem666](https://avatars.discourse-cdn.com/v4/letter/d/258eb7/32.png) [@DevilMayhem666](https://boards.straightdope.com/u/DevilMayhem666)\ **Post date:** [November 24, 2013, 4:59am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/34 "2013-11-24T04:59:32Z")
In the animal kingdom a parent lets go of their child after they taught them how to survive and are physically grown, rather than going by the number of birthdays their young has had. I believe that when a person who completes secondary education and puberty should be considered an adult. ---
**Author:** ![drewtwo99](https://avatars.discourse-cdn.com/v4/letter/d/d07c76/32.png) [@drewtwo99](https://boards.straightdope.com/u/drewtwo99)\ **Post date:** [November 24, 2013, 5:51am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/35 "2013-11-24T05:51:34Z")
How about a checklist where you have to complete X out of Y in order to be considered an adult? 1. Lift 70 lbs right over your head. Rawr! 2. Ejaculate or menstruate into this cup to prove you can reproduce. 😉 3. Write an essay explaining why republicans are evil and you will never vote for them. 😃 4. Get at least 80% of the following math questions correct [list a bunch of arithmetic problems] 5. Suggest your own criteria for what should be on this list of maturity checklist and then determine whether or not you pass it 6. Beat every level on Angry Birds with 3 stars, none of those cheating things you buy! …etc ---
**Author:** ![runningdude](https://avatars.discourse-cdn.com/v4/letter/r/e9c0ed/32.png) [@runningdude](https://boards.straightdope.com/u/runningdude)\ **Post date:** [November 25, 2013, 3:53am UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/36 "2013-11-25T03:53:43Z")
In the United States, its because that when you could join the military. The US Constitution hints at age 21 being considered the age of majority (age that one could run for the House of Representative), and up until the mid twentieth-century, this was the voting age that most states had set. Biologically, adolescence extends until about age 22. Historically speaking, ages 21 to 24 were considered the age of majority in many parts Europe (I specifically know of the 1600’s +/- ). Eighteen I think is simply when secondary school ends. Historically, this happened anytime after age 13. I’ve read that Harvard had 16 years enrolled around the time of the Revolutionary War, although it may have functioned as a hybrid high school/college back then. ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [November 25, 2013, 4:50pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/37 "2013-11-25T16:50:31Z")
> [@Der\_Trihs](#): > > More like, we don’t _actually have_ a “maturity test” to give them in the first place. The idea of a formal, standardized “maturity test” seems to be pretty much a non-starter due to reasons mentioned here and elsewhere. I know that there are several social groups that have “coming of age” or adulthood rituals that mark a person’s acceptance as an adult. A Jewish boy who has completed his Bar Mitzvah is considered an adult for ritual purposes. E.g. if you need at least X adult Jews in order to complete Y ritual, you can use 13 year old boys - it doesn’t matter that local secular law does not recognize their adulthood. Some coming of age rituals in some societies may involve ordeals or elements of hazing, but I was under the impression that the intent was that everyone or almost everyone passes. The ordeals are more to instill a sense of camaraderie and pride and pass along collective knowledge than serve as an actual evaluative instrument for maturity. The only way to meaningfully fail is to refuse to undergo the process. In other words, the only real test is one of intent. If you want to pass, you will, since skills, etc. are not actually being graded. Are there any societies, religions, ethnic groups, etc. that have a coming of age ceremony that in some way can be meaningfully considered a _test_ that some people are _expected to fail as a matter of course_ and presumably remain “children” until such time as they manage to pass it, if ever? ---
**Author:** ![Blaster\_Master](https://avatars.discourse-cdn.com/v4/letter/b/cab0a1/32.png) [@Blaster\_Master](https://boards.straightdope.com/u/Blaster_Master)\ **Post date:** [November 25, 2013, 6:54pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/38 "2013-11-25T18:54:19Z")
As others have said, here in the US, in most states, 18 is more or less considered to be an adult, but there are still some age restrictions beyond that. You have to be 21 to drink alcohol, often you have to be 21 to own a handgun, there’s also constitutional restrictions on holding various public offices at 25, 30, and 35. Even still if you can vote and smoke and be drafted and all at 18, you’re still not an adult in many people’s eyes in the sense of how you’re treated, that’s often not until at least 21-22, because of college and simple biology of brain maturity. Personally, though, I don’t like the idea of a single age for all the various rights and responsibilities because maturity isn’t like that. I’d much rather see various rights and responsibilities get ages ranging roughly from 15 to 25 based upon research about maturity. Maybe grant rights or responsibilities at an age research shows some general point can handle it, say a standard deviation or two above the mean for example, and for those who for whatever reason feel they’re mature enough and need it can pursue it legally, like kids that get legally emancipated. Speaking for myself, 18 was scary because it seemed like a light switch going from childhood to adulthood, at least from a legal perspective. There were definitely some things I was ready for and had been for a few years, but there were also a few things I would have been better off waiting a little more for. Plus, I think giving someone privileges and responsibilities in a phased approach makes it easier for them to get accustomed to. ---
**Author:** ![IvoryTowerDenizen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ivorytowerdenizen/32/17937_2.png) [@IvoryTowerDenizen](https://boards.straightdope.com/u/IvoryTowerDenizen)\ **Post date:** [November 25, 2013, 6:58pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/39 "2013-11-25T18:58:31Z")
> [@robert\_columbia](#): > > The idea of a formal, standardized “maturity test” seems to be pretty much a non-starter due to reasons mentioned here and elsewhere. > > I know that there are several social groups that have “coming of age” or adulthood rituals that mark a person’s acceptance as an adult. A Jewish boy who has completed his Bar Mitzvah is considered an adult for ritual purposes. E.g. if you need at least X adult Jews in order to complete Y ritual, you can use 13 year old boys - it doesn’t matter that local secular law does not recognize their adulthood. > > Some coming of age rituals in some societies may involve ordeals or elements of hazing, but I was under the impression that the intent was that everyone or almost everyone passes. The ordeals are more to instill a sense of camaraderie and pride and pass along collective knowledge than serve as an actual evaluative instrument for maturity. The only way to meaningfully fail is to refuse to undergo the process. In other words, the only real test is one of intent. If you want to pass, you will, since skills, etc. are not actually being graded. Are there any societies, religions, ethnic groups, etc. that have a coming of age ceremony that in some way can be meaningfully considered a _test_ that some people are _expected to fail as a matter of course_ and presumably remain “children” until such time as they manage to pass it, if ever? Your point is a good one. With respect to a Jewish girl (at 12) or boy (13)- they do not have to have an ceremony at all to be considered an adult. They don’t _have_ a Bar/Bat Mitzvah, they simply _become_ a Bar/Bat Mitzvah. No test of proficiency or ceremony needed. So like our 18 year old standard, just reaching the milestone of years is sufficient. ---
**Author:** ![That\_Don\_Guy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/that_don_guy/32/538_2.png) [@That\_Don\_Guy](https://boards.straightdope.com/u/That_Don_Guy)\ **Post date:** [November 25, 2013, 8:10pm UTC](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507/40 "2013-11-25T20:10:30Z")
> [@RealityChuck](#): > > The US originally adopted 21 from British common law; it was supposedly derived from the age a squire was allowed to be a knight (note that it was not true across the board: King Richard II was crowned king at age 10). IIRC, this is because it was felt that it took 7 years for someone to become old enough to be a Page, seven years as a Page in order to be a Squire, and seven years as a Squire in order to be a Knight. [Previous page](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507.md?page=1) [Next page](https://boards.straightdope.com/t/why-is-18-considered-when-you-become-an-adult/673507.md?page=3)