His argument is that it is easier for kids to get pot than beer--and if we made marijuana legal, it would be harder for them to get.
This is a rather astonishing claim, since simply by being legal, it would reduce the price and increase the number of retail locations. In spite of alcohol being legal, and considerable regulation, it is not at all difficult for teens to get access to alcohol. They get it from sympathetic young adults and from parents (with or without parental awareness). I pointed out that this is a real risk with marijuana. Adding marijuana to the existing problem of alcohol abuse is likely to make things worse. Being half wrong (our current situation where alcohol is legal but marijuana is not) is better than being completely wrong.
His response was to say, "If you are really worried about teenagers (I don't believe it for a minute)"
I've made it clear for a very long time that my primary concern about marijuana availability is the mental illness risk, and that risk appears to be primarily for those who start smoking it before the years that schizophrenia hits--teens to 20s. To make such a statement is to call me a liar.
Why do potheads insist on turning their intoxicant into a religion? This is not the first time that civil discussions have turned bad because potheads are so hopelessly insistent on seeing every difference of opinion as dishonesty. If they were pushing for a religion, it would be obvious that they were fanatics.
There must be people who get this fanatical about alcohol. I just never get into conversations with them, I guess.
UPDATE: For those who think that marijuana was made illegal because of anti-Mexican feeling, how to explain Mexico's making it illegal when its use in the U.S. was still quite rare? From The Plant World 11:181 (1907), describing the author's first seeing of marijuana:
it was of common growth in central and southern Mexico, where however, "taboo" had been placed upon it by the Mexican Government. Under flaring head-lines a recently published newspaper article recites the seizure of "eight large boxes of marijuana, the largest collection of the national dope weed of the Mexican peon ever captured in a single haul by the police, and perhaps the greatest quantity of this weed ever seen at one time out of the field." * * * "Enough of this brain-wrecking weed was seized to have caused any number of murders had it reached the poor persons for whom it was intended.'' * * * "The effects of marijuana are like, but worse than those of opium. It has the tendency to craze the brain of the smoker. The weed has a pleasant aromatic odor and its immediate effect when smoked is considered more seductive than opium, but in the end it produces a murderous mania. To fight its use among soldiers is one of the hardest tasks before the army authorities.''UPDATE 2: There is a widespread belief that Prohibition did not reduce alcohol consumption--largely coming from ideologues who just know that laws don't change behavior. One of the best proxies for alcohol consumption is cirrhosis of the liver death rates.
If sold in the tedejons of Mexico, and detected, the tendero is arrested, his store closed, his goods confiscated and he is either sent to the army or the penitentiary. In Tucson it is grown to supply the trade which amounts to, so my convict friend informed me, an average of $2.50 per day. The Mexican railroad laborers, he said, use all that is grown here outside of what they are able to purchase at the drug stores. There are several small gardens bordering the river in which the plant is grown, but the fear of publicity and punishment leads the growers to suppress this fact where possible.
Remember that many states had already gone "dry" before Prohibition went national in 1920, so it is not surprising that the cirrhosis of the liver death rate started falling in 1910, and stayed at half the 1910 rate until the 1960s--when alcohol consumption rates (the gray part of the graph) started to rise.