In my opinion, this would be impossible to assess. What would your proposal around determining this, be?
There are several possible approaches. The psychologist Robert Epstein (T
he Case Against Adolescence: Rediscovering the Adult in Every Teen, New York: Quill Driver Books, 2007) advocates government administration of competency tests to adolescent youth, with the premise being that successful passage of such tests indicates sufficient competency for what's presently defined as "adult" life. He writes:
Young people should be extended full adult rights and responsibilities in each of a number of different areas as soon as they can demonstrate appropriate competence in each area. Passing appropriate tests will allow competent young people to become emancipated, sign contracts, start businesses, work, marry, and so on, but I am not suggesting that young people be given more "freedom." We need to start judging young people by their abilities, not their age, just as we're now increasingly doing with the elderly.
Though my opposition to competency tests has waned to some degree in recent years, it still remains to some extent. Aside from the more standard technical objections (whether criteria determination would be fair and objective, whether these tests could actually reflect technical ability, whether there would be certain areas where there would exist a propensity towards inaccurate results, etc.), I genuinely don't believe that competency tests are
necessary in most cases. I'm of the belief that the best means of illustrating sufficient ability to exercise the rights and responsibilities of self-determination is to
attempt it. Failure could mean a longer period of parental dependence and preparation for re-engagement in such exercises, and success could mean the gradual expansion of self-determination to all other facets of life. I can of course imagine a number of objections that you may have to such advocacy, and this and another thread has prompted me to start a thread specifically devoted to this topic. I'll probably do that sometime over the weekend when another person who I know would have a strong interest in the discussion will return.
"Maturity" is a question-begging term. We use "he's mature for his age" to describe a child or teen that has more sense, intellect and self-restraint than is commonplace.
Maturity, however, is more than just those things. Experience is one of the greatest differences between an exceptionally intelligent 15yo and an average-intelligence 25yo. It is the difference between knowing something intellectually, because you read it in a book, and knowing something in your gut because it actually happened to you (or in your presence) IRL.
I don't believe we can use such experience differentials to warrant or justify vastly different forms of legal treatment for those respective age groups any more than they could be used as such justification for inequitable treatment between those in their mid-20's and those in their mid-30's. We need to recognize the reality that individuals vary tremendously in their respective experiences and behaviors learned from those experiences, and that age alone is thus not a sufficient criterion for discrimination. Matters are complicated further when we consider Joshua Meyrowitz's (
The Adultlike Child and the Childlike Adult: Socialization in an Electronic Age, Daedalus, Vol. 113, No. 3, Anticipations (Summer, 1984), pp. 19-48) observation that
"those who insist upon the "naturalness" of our traditional conceptions of childhood are basing their belief on a very narrow cultural and historical perspective. Childhood and adulthood have been conceived of differently in different cultures, and child and adult roles have varied even within the same culture from one historical period to another.”
IIRC there is also the issue of brain structure maturity, that those parts of the brain relating to impulse control and so forth do not fully develop until around 20-25.
I wouldn't be so certain to use that as justification for preconceived stereotypes if I were you, much less justification for discrimination in terms of legal policy. I wouldn't personally deny that MRI and fMRI scans (presumably what you're referring to) provide us with intriguing observations of physical brain development, but we must be cautious about extrapolating data from these scans in an attempt to form broad policy approaches, as Jay Giedd, Laurence Steinberg, and Deborah Yurgelun-Todd have been far too quick to do, in my opinion. The chief opponent of this approach thus far has been the aforementioned psychologist Robert Epstein (former editor of
Psychology Today), who writes this in
The Myth of the Teen Brain, published in
Scientific American Mind:
This work seems to support the idea of the teen brain we see in the headlines until we realize two things. First, most of the brain changes that are observed during the teen years lie on a continuum of changes that take place over much of our lives. For example, a 1993 study by Jésus Pujol and his colleagues at the Autonomous University of Barcelona looked at changes in the corpus callosum—a massive structure that connects the two sides of the brain—over a two-year period with individuals between 11 and 61 years old. They found that although the rate of growth declined as people aged, this structure still grew by about 4 percent each year in people in their 40s (compared with a growth rate of 29 percent in their youngest subjects). Other studies, conducted by researchers such as Elizabeth Sowell of the University of California, Los Angeles, show that gray matter in the brain continues to disappear from childhood well into adulthood. Second, I have not been able to find even a single study that establishes a causal relation between the properties of the brain being examined and the problems we see in teens. By their very nature, imaging studies are correlational, showing simply that activity in the brain is associated with certain behavior or emotion. As we learn in elementary statistics courses, correlation does not even imply causation. In that sense, no imaging study could possibly identify the brain as a causal agent, no matter what areas of the brain were being observed.
Similar analysis is typically regarded to come from sociologist Mike Males,
The "Teen Brain" Craze: New Science, or Ancient Politics?, though his approach primarily centers around evaluating the apparent lack of a connection between physical brain development and the actual
behaviors of adolescents and similar age youth, since it would seem that a faulty or underdeveloped brain would make one inclined to greater risk-taking and similar behaviors. He writes this:
1. Adolescents, immature brains and all, are doing far better today than the supposedly cerebrally-developed midlifers complaining about them.
2. Scientists always seem to find biological flaws in the brains of populations that politicians and the public find fearsome or blameworthy for social problems.
3. The preponderance of laboratory research does not find significant differences between adult and teenage cognitive ability.
4. Scientists have not compared teenage and adult risk taking on a level playing field.
...
Conclusion: The supposedly immature brain development that renders teenagers naturally risk-prone mysteriously fails to affect teenagers from more affluent backgrounds, or from Europe or Japan (where youth poverty rates and dangers are low), who routinely display risks lower than adults do. Rather, “science’s discovery” of the problematic “teenage brain” is just the latest in a long, disgraceful history of alliances between officials, interest groups, sensational media, and a small number of scientists who serve their needs. The ability of authorities to scapegoat unpopular, powerless groups in society instead of facing difficult social problems—in this case, rising middle-aged drug and crime epidemics and the effects of poverty on youth risk—endangers Americans by preventing realistic solutions to serious crises.
Of far greater interest to me personally is the literature on the actual mental abilities and competence of adolescents and other youth to make rational and informed decisions, not snapshots of physical brain development that may necessarily diverge from analyses of actual mental functioning: effectively another necessary distinction between "the brain" and "the mind." I've referred to some of it here in the latest thread about parental notification/consent for abortion. And as I said, I'll probably be starting a thread devoted specifically to that topic, and I'll expect that you'd be interested in contributing.