1. By this logic, a teenager is unable to make any decision regarding his health, safety or well-being. So they shouldn't be allowed to drive at all. They also shouldn't be allowed to eat unacompanied by an adult since they aren't capable of making healthy decisions. Etc.
2. The argument implies that there is a correct decision so any adult who opts out is clearly incapable of making the smart decision to begin with. Is not the safety of an adult's brain worth more than his right to make poor decisions? Therefore, adults should also be subject to this law which will force them to make the correct decision!
1. Actually, in NJ (since this is where the helmet law applies) you must be 17 to get your PROVISIONAL license (cannot drive between 11pm-5am, cannot drive with more than one person in the car not in your family, etc.) and you dont receive your license until the ripe age of 18..lets not get into semantics, but 18 is generally considered the age by which you are old enough and mature enough to be considered an adult and to make serious decisions regarding your own health and future. Think about it - think about how you can't get your own health insurance until you're 18, you can't sign yourself out of school (even if you're sick), you can't do pretty much anything..
2. No this argument implies that a teenager isn't old enough to maturely weigh his options and make a smart decision one way or the other. As an adult, it is assumed that you are smart enough and mature enough to weigh the benefits of wearing a helmet vs. whatever cons you might feel there are, and make an educated decision based on that and assume the responsibility that accompanies that risk.
You're grouping adults and minors together when they shouldn't be - if the government and the country viewed adults and minors as having the same levels of cognitive reasoning to determine what is and is not the correct course of action, then there wouldn't be age restrictions on many things.