The general idea behind the raising of alcoholic drinking age is that it protects young people who are still incapable of accepting responsibilities, from the abuse of alcohol. It is, however, very doubtful whether it performs this function.
The matter is, the more something is prohibited, the more appealing it looks for those who are prohibited to do it. A person who would have been drinking from time to time, if he were allowed to, will be drinking immoderately and in secret if he is forbidden to do it, for the simple reason of it being cool. Moreover, with the minimum alcohol drinking age being 21 years, the situation looks especially ridiculous. At 18 people are considered to be mature enough to take responsibilities, get married, vote, sign contracts and be persecuted by law if they break it; but officially they still are not allowed to drink until they turn 21.
It would be naive to suppose that restriction laws like this can protect somebody from something. Young people may be prevented from drinking in bars, but who will stop them from drinking in all kinds of places and situations when drinks become available? If a person doesn’t treat alcohol as something overly exciting, mysterious and unattainable, he will most likely treat it as just yet another aspect of life, which is capable of being fun but nothing more. If he is prohibited from drinking it is more than probable that he will plunge into drinking once he is allowed to.
And yes, doesn’t history teach us anything? The Prohibition in the early 20th century was supposed to eliminate alcohol abuse altogether; instead, government enforcement brought what it usually brings: great waste of money, emergence of great crime families without lowering the quantity of consumed alcohol at all.