by Patrick Appel

Ben Casnocha tweaks Kant's moral maxim:

In Kant's Categorical Imperative he includes this moral maxim of universality: "Act only according to that maxim whereby you can at the same time will that it should become a universal law without contradiction." In other words, if your action were to be the action everyone was taking, would you still do it? The implications of Kant to non-voters would be, "If everyone chose not to vote, the democracy wouldn't function. So vote!"

That seems like a fine aspirational ethic -- a principled stance applied to things like democracy and drug buying -- but the more realistic approach would to weigh the probability of universal adoption of the action.

If it's insanely low -- like in the case of non-voting or drug-buying -- then ignore it. If, on the other hand, there were only five total drug buyers in the world, and if you stopped buying drugs that would drastically shrink demand and perhaps result in less drug violence, you would be right to incorporate societal implications more seriously in your decision as they much greater.

I'm with Kant.

Casnocha doesn't object to drug use but to drug purchases funding other criminal activities. Drug use, in moderation, doesn't violate Kant's moral maxim; a world where everyone smokes a joint once in awhile wouldn't be much different than the world we live in. And drug violence could largely be resolved either by drug users quitting en masse or by legalization. Casnocha's maxim falls further apart when applied to other moral dilemmas. Take this post by McArdle on pedophilia and child pornography from earlier in the week:

Dan Savage a couple of weeks ago had a letter from a pedophile who has never done anything about it: never used child porn, never touched a child, doesn't even let himself look at children in public places.

In some sense, people like this--the pedophiles who never do anything, and do their damnedest to keep from even thinking about it--are exercising a virtue that borders on the saintly.  They're struggling mightily with a powerful desire that they exert rigid control over.  Society should gather round to help them, tell them what a great job they're doing, give them other ways to channel the energy they aren't pouring into molesting kids, and substitutes for the emotional succor that most of us hope to get from our partners.

No one would argue that this pedophile should "weigh the probability of universal adoption" before making the decision not use child pornography. Kant's maxim only works well when debating the direct effects of an action. If one buys marijuana it is possible that they funding other criminal activities. If one consumes child pornography they are directly supporting a heinous act.