Slashdot posts an essay by a fellow who used Amazon’s Mechanical Turk program to offer micropayments to folk willing to argue with him—which I’d have thought was unnecessary in an age when blogs are awash in folk happy to argue for free. The argument, incidentally, is quite terrible:

1. Government should ban smoking by people under 18, because of the harmful health effects.
2. If that’s true for the entire group of underage smokers, then it’s also true for each individual smoker under 18. In other words, even if only one person under 18 smoked in the entire country, it would still be justified for the government to ban them from smoking.
3. Whatever bad health effects are caused by the average person under 18 smoking 1 cigarette, there is some number N cigarettes that would cause the same bad health effects in the average adult who smoked them.
4. If banning 1 person under 18 from smoking 1 cigarette is justified (even if they were the last smoker on Earth), and the health effects would be the same for an average adult who smoked N cigarettes, then banning 1 adult from smoking those N cigarettes would also be justified (again, even if they were the last smoker on Earth).
5. If banning 1 person over 18 from smoking would be justified, then the same logic would apply to every person over 18, which would imply banning smoking for all people over 18.
6. Hence, if you believe that smoking should be banned for people under 18, then the same logic would lead to a ban on smoking for people over 18 as well.

This goes wrong at the very first step: The rationale for banning minors from smoking is not “the harmful health effects,” but that minors are in no position to reasonably accept or consent to those effects after weighing the risks and benefits.

Though the entire center of the argument seems quite superfluous—is some point served by moving from the type to the token, and then back to the type?—the second step also looks invalid. Prohibitions have enforcement costs, and so obviously a policy that produces some benefit for a large number of people can’t be assumed to be justified when it produces the same benefit for just a few. We don’t build roads out to the cabins of a few hermits just because we’d build a road to the same location if it were a bustling metropolis.

Step three suddenly begins talking about a ban on smoking even one cigarette, and then makes the jump to some number of cigarettes N which would do comparable harm to an adult smoker. Insofar as one is inclined to entertain an argument already this confused, this infects the rest of the inferences by blurring the distinction between a full ban and a mere limitation that would achieve the same effect. Some persons might be rendered unfit to drive after one glass of Scotch, making it legitimate to bar them from driving. And surely for any person, there’s some number N of Scotches that would render them equally unfit to drive. It obviously doesn’t follow that this provides equal justification for barring everyone from driving after a single glass of Scotch.

Step four arguably just recapitulates the error of the first step, in that assumes the reason for the prohibition on minors smoking is just the consequence, rendering the choice to smoke equally bad in all cases. But it’s probably worth noting that there are really two issues here. The first is that the “same” consequences will be weighed differently by different people, which means there’s no objective measure of whether a particular health risk is worth it, on net, without knowing anything about the value a particular subject places on health relative to the pleasure derived from the action. The second is that even if we grant a particular judgment is bad, respect for that bad judgment may represent the sort of deference that a fully developed, autonomous person is due.

Oddly, the author makes no mention of these fairly elementary points, which either means that he didn’t think they merited consideration, or that none of his interlocutors broached them. So maybe trying to buy cheap arguments isn’t all it’s cracked up to be after all.