Kevin Drum picks up on John Ingold’s article posing the question whether cannabis is, net, a substitute for alcohol or a complement to it. His post raises two somewhat technical but important (and policy-relevant) issues.
1. Kevin considers the substitution case and the non-substitution case (zero cross-elasticity of demand). But complementarity is a real possiblity, either because the two drugs go together – as alcohol does with cocaine, for example – or because people develop a taste for intoxication by heavily using one drug that they gets carried over to the other.
2. Kevin correctly identifies price as a key variable: we simply don’t have experience with pot as cheap as it would be (on a potency-adjusted, inflation-adjusted basis) if it were a free-market product. (Regulation and taxation could change that, so it’s not really meaningful to talk about a post-legalization price without specifying the legalization regime.)
But it’s not right to say that “marijuana isn’t cheap enough to be a genuine substitute for alcohol.” On what seems to me the right basis of comparison – cost per unit intoxication – illegal cannabis is actually cheaper. Assume $15/gm. as the price of moderate-potency (15%-20% THC) pot. Assume that a joint of that material weighing 0.4/gm. is enough to get two (non-tolerant) users stoned, to the level they desire, for three hours each. Then $6 worth of pot produces roughly 6 person-hours of intoxication, for a cost of about $1/hr.
Now consider a non-tolerant user of alcohol. A beer costs about a dollar, and for an average-sized person about four beers in a row are needed to get to the .08 level that legally counts as impaired. Maintaining that BAC – which might not actually maintain the initial subjective intoxication level – requires roughly another drink an hour. So three hours intoxicated would cost about $6, or $2/hr.
Of course this is all very approximate; I know of no standard measure of intoxicated pleasure, so I can’t say whether .2 gram of 15%-20%-THC pot is really equivalent to six beers over three hours. And of course tolerance complicates the problem, along with the issue of people who want to alter their mood short of full intoxication.
Still, at first blush marijuana, even under illegality, seems like a bargain in mood-alteration. Which is a good reason to design legal regimes that don’t let those prices fall very much.
Footnote I’m grateful to Kevin for mentioning our book. But note: our book, not my book. The authors are Caulkins, Hawken, Kilmer, and Kleiman.