Lowering the drinking age

Here is another reader request:

There’s been recent talk about what would happen if the legal drinking age were lowered to 18. Would there be a net increase or decrease in risky binge drinking, accidents, etc?

New Zealand lowered its drinking age to 18 in 1999 and bad consequences followed, including a higher rate of drinking-related car crashes.  Illegality, even when it can be circumvented, really does raise the price of an activity in many instances. 

Nonetheless I still think that 20-year-olds — legal adults in just about every other way — have the right to drink alcohol.  Sometimes I call myself a "two-thirds utilitarian."  I am a pluralist who thinks that utility is often but not always the primary consideration behind policy choice.

There’s always another paternalist intervention to save children’s lives but no one is for all of them.  We could ban swimming pools and buckets for instance.  We could ban high school football.  We could raise the drinking age to 25.  How about a drinking age of 50?  How about a driving age of 21?

I see at least two major analytical questions.  First, how much normative force should "extra death" have in a policy argument?  Second, what is special about the number 18?  Consistent with the latter question, I think that 15-year-olds should be able to drink in a restaurant when clear parental permission is present.