You can’t be so arbitrary about age and decisions like that–the ability to make appropriate decisions depends on the decision being made.
There are many 16-year-olds far more safe and able with a firearm than many 46-year-olds.
There are many 18-year-olds better at handling money than 38-year-olds.
There are many 18-year-olds capable of handling the stresses of war, whereas there are many 30-year-olds who enlist who can’t even handle Basic Individual Training.
My point is simple: The problem with decisions being made by a central body that is often out of touch with reality is that they should not be generalizing and making a hard line concerning so many subjects.
BUT, I do believe that 18 is too young of an age to be calling people ‘legal adults’ and assuming that they have the mental capacity to make appropriate decisions mostly across the board. I don’t think that they have enough understanding of life to intelligently vote, or to understand what they are signing when they sign contracts or make heavy financial decisions, or to sign a lease to an apartment.
Science tells us that the brain doesn’t fully mature until age 25 (on average), so I think that pushing many of these things back until age 21 is not necessarily a bad thing. But if we do that, we have to officially adjust the age that we consider citizens to be “legal adults” to age 21 as well. If we are unwilling to do that, then we will have issues with applying arbitrary ages to certain activities.
But if we do that, then we have the issue about a central government making broad-sweeping decisions for numerous activities for 321-million people, and again, I take issue with that. Maybe we should leave some things up to the states (things, for instance, that are not included in the constitution, like gun ownership and voting) and make some a national thing. Of course, that’s where we are now, so maybe there is no good answer–I just know that the answer is not to give all of the power to a central government for 321-million people.
edit on 6-3-2018 by SlapMonkey because: (no reason given)