Nothing much to add except that I came across Reefer Madness on IFC right after reading this thread. People here are clearly ignoring the dangers of marijuana or “wacky weed” which apparently include sex, wild piano playing, murder and Negros lusting after white women.
Seriously? And here I thought that reefer madness was supposed to be completely divorced from reality. 
Sorry, I was thinking of friends who have died or nearly died withdrawing from alcohol. Let me clarify what I meant by the use of the words “physical addiction”: marijuana does not produce life-threatening medical emergencies upon withdrawal. I don’t think of “withdrawal” as something like a hangover, a day of feeling a little crappy and having some mild emotional discomfort such as anxiety. I think of withdrawal as being something more serious. The way I think comes from personal experience and the experiences that others have shared with me.
There is still much unknown about the mechanisms and different types of addictions. I will also concede that there is quite a bit of disagreement among professionals involved in helping addicts or studying addiction. I come here to fight my ignorance, so I would be interested in any cites to more specific information about physical dependence/significant withdrawal among those discontinuing marijuana. I’m afraid the cites you provided, however, do nothing to change my mind. The first two links don’t even claim that marijuana causes physical dependence, and the third link, which you quoted, makes only vague reference to “some signs” and to some “animal studies”. In spite of a portion of the essay being entitled “Physical Dependence” the authors fail to convince me that marijuana can cause physical dependence.
I will clarify my earlier statement by saying “marijuana does not appear to produce life-threatening detox situations.” Better?
While I agree that smoking pot is “better” than drinking in almost every way I really don’t think legalizing pot is going to make kids, or anyone else, drink less. When I smoke I like to have a beer (with my huge bag of chips.) Alcoholic drinks are tasty. If a young person is at a party with beer and pot, why would he not use both? I worry that the combination would make a kid less able to control his drinking. That said, it’s not like the legality of pot has a huge effect on college kids using it except that it makes the price higher.
I love some alcohol but it is a killer of a drug that would be outlawed if it wasn’t already such a part of our lives. Suggesting that some other substance is not as bad is setting the bar pretty damned low.
It is much harder to tell if a person is high than if they are drunk and I believe that is a major componant of the fear of pot. There is a simple test for drunk driving but high driving is impossible to prove (except maybe with a blood test?) but should still be avoided. If my child or an employee is drunk I think I can tell but pot is much more subtle.