The famous "Martian Test" is really quite simple: that is, can you hypothetically explain your position to a Martian without sounding like a complete idiot? The 21 drinking age (and smoking age, toking age, etc.) clearly fails that test, big time.
If a given substance (regardless of what it is) is allegedly so apocalyptically dangerous that legal adults age 18-20 must be categorically banned from using it, thus arbitrarily carving out a three year exception to the age of majority, because reasons, backed by the full force of the law, why the hell is it even on the market at all in the first place?
Any answer justifying this bizarre state of affairs would thus fail the Martian Test:
If you have to literally invent new laws of nature in an attempt to explain why, that fails the Martian Test (and also fails Occam's Razor as well).
If you have to appeal to either tradition OR novelty, or indulge any other logical fallacies whatsoever to support your thesis, that fails the Martian Test.
If you speciously claim that 18-20 year olds are too fragile and/or immature to be trusted with full adult rights and bodily autonomy, but have no problem with sending them to war, executing them, trying them as adults, etc., that fails the Martian Test.
If you have to selectively (ab)use the precautionary principle, ad hoc, that fails the Martian Test.
If you have to cherry-pick the puny molehill of mainstream OR fringe "evidence" in favor of such restrictions while ignoring the massive mountain of evidence against such, that fails the Martian Test.
If you have to be disingenuous or intellectually dishonest in any way, including citing long-debunked fatally flawed "evidence", you fail the Martian Test.
If you have to resort to trolling or temper tantrums when you clearly lost the argument, you fail the Martian Test. And you are a sore loser as well.
If you have to resort to some flavor of "do as I say, not as I do", you utterly fail the Martian Test. And you prove yourself a flaming hypocrite on top of that.
(Ditto if you point out the mote in your opponent's eye while missing the log in your own.)
If you resort to the "weaker brother principle", which easily devolves into the "tyranny of the weaker brother", especially if you do so selectively, guess what? You still fail the Martian Test, big time.
And finally, if you appeal to "pragmatism" to justify it, you may very technically pass the Martian Test by the very skin of your teeth, but at the cost of utterly compromising one's moral principles. Either way, it's not very flattering at all, buddy. Checkmate.
Now get down off of your high horse, admit you were simply a bigot all along, apologize, and make amends.
QED
UPDATE: One should note that arguments which favor some version of "punishing the many for the excesses of the few" technically do not always fail the Martian Test, but are still highly unethical regardless.
