OK, a few things. (Do not bother reading this post if you're not interested in drugs. I go to school to study this kind of stuff and I do a lot of extracurricular research so I have a lot to say about the subject, so this will be tl;dr for a lot of people here.)
First of all, on the "addictive" power of marijuana. From a medical standpoint, one of the most important measures of the damage done by an addiction is the intensity of withdrawl symptoms. Basically, something is addictive if the user experiences negative symptoms like pain or health problems if they are denied the drug. Cigarettes are extremely addictive because nicotine binds to receptor sites all over the body, and therefore the entire body's nervous system is calling out for it every time a hardcore smoker goes too long without it (I've heard that it's absolutely terrible). Opiates (OxyContin, morphine, heroin, Percocet, etc.) are extremely addictive because of the neural pathways they affect, and the resultant fact that withdrawing from painkiller addiction feels a bit like having third-degree burns all over your body for days. Alcohol is actually the worst when it comes to addictions because it's the only widely abused drug that can and will actually flat-out kill you if you try going cold turkey after delving too deep into addiction. A hardcore heroin junkie will probably want to die for an entire month after going cold turkey on heroin (and as such will probably relapse) but a hardcore alcoholic (we're talking lifetime) who tries to go cold turkey will just die, their heart will give out and they will drop like a rock. A slightly less harder-core alcoholic will suffer delerium tremens. Alcohol is really, really destructive from the standpoint of addiction.
A hardcore stoner, the hardest-core stoner, someone who smokes superstrong crazy weed 10-15 times a day despite having zero medical reason to do so (of which there are several, by the way, including glaucoma, arthritis, and appetite stimulation during chemotherapy) will probably suffer some pretty serious irritability problems for about a month or two if they stop smoking pot. They won't be happy about it, but they won't suffer anything even remotely close to the magnitude of seriousness that is heroin, nicotine, or alcohol withdrawl. Even withdrawing from caffeine is more difficult than withdrawing from weed, at least on a purely biochemical level. It's quite true that lazy losers have a tendency to be severely enabled by smoking weed and as such you see a lot of very unwise use of it, but this is a problem with the attitude people take towards using it, not a property of the drug itself that causes this phenomenon. Basically the risk of serious cannabis addiction is virtually zero, if addiction is defined according to medical symptoms associated with use and withdrawl. "Addiction" to cannabis is a bit like being "addicted" to coming in to work late (which, I'm sure someone will argue here, can be a serious problem for some people).
Oh, and the last study done on the link between weed and cancer found literally zero indication that weed increases cancer risk. That's not as huge and amazing as it sounds, because they had to control for cigarette smoking among their subjects and so there was a pretty serious confound, but if you trust statistics as a discipline, the fact that they found a 2000% (20X) increased risk for cancer due to cigarette smoking compared to a 0% or even negative risk associated with weed, it starts to make you think.
(Source)Oh, and the second-largest organization of medical professionals in the nation just endorsed medical marijuana and called for research!
It's not physiologically addictive (unlike caffeine, nicotine, alcohol, and a great many pharmaceuticals), it's not neurotoxic, it's not associated with cancer risk, lots of doctors are ready and willing to accept it as legitimate medicine ... the evidence pretty strongly suggests that marijuana usage is effectively harmless if treated with a modicum of sense, and minimally problematic even for people who don't give enough of a shit to treat themselves with respect as they use drugs.
On the subject of psychedelics ...
I am certain that psychedelics hold a universal potential for personal development (which I define as self-directed improvement in quality of life). What little research that has been done on them has shown that they are surprisingly effective at a wide range of psychologically therapeutic tasks if used correctly, including treatment for alcoholism and opiate addiction, post-traumatic stress disorder, cluster headaches, obsessive-compulsive disorder, and maybe even anxiety and depression (It's important to point out that different psychedelics are useful for different things. I'd need to go into specifics if I were to explain each of the treatment possibilities I mentioned but you can rest assured that I'm not making any of it up.) So from a medical standpoint, they at least have potential as treatments for certain disorders.
However, they also have the unique capacity (among drugs) to make a person who is physically and mentally healthy somehow even more well. This was actually researched recently ... Johns Hopkins published a study in which researchers gave psilocybin (the stuff in "magic mushrooms" that makes a person trip, more or less similar to LSD in effect and duration) to healthy, normal, middle-aged volunteers who had never taken psychedelic drugs before (but DID engage in spiritual practice or activity such as church worship, meditation, prayer, yoga, etc.) The results were actually pretty incredible. A full third of the people who participated in the study said that it was the most important thing that had ever happened to them. Another third ranked it in the top 5 (alongside landmarks like the death of a parent or the birth of a firstborn child). Here's the kicker ... at 2 months, 6 months, and 12 months after the study, exactly zero of the participants reported any sort of lasting negative effect (only 30% reported negative effects of any sort even during the experimental sessions), and they all performed equally well on any test given before and after the experiment. If nothing else, the study proved that it was safe for healthy people to take psilocybin in correctly controlled environments, which is a huge step towards further understanding exactly what it actually does. The last and most powerful result of the study, though, was that more than 80% of the people who participated said, a year later, that they were better off for having done so. More than 80%! That is HUGE. (If you want to follow up on this study, it was conducted by Roland Griffiths and published in the journal
Psychopharmacology. I forget the date.)
Obviously, as with any other drug, positive results rely upon well-reasoned and responsible use, preferably with the help of a professional. Unfortunately there is a serious shortage of professionals who are trained in psychedelic administration (they just don't make shamans like they used to these days) and even the medical establishment knows next to nothing about how they could be reasonably used. So recommending psychedelics to anyone would be jumping the gun in a serious way.
But when 80% of healthy volunteers give resounding positive feedback and 0% give negative feedback, it's worth paying attention to. That never happens in drug trials. Those numbers would sound ridiculous to me if I didn't already know firsthand how much good mushrooms can do for a person.
Basically, the POTENTIAL for benefits granted by psychedelics is, I think, universal. But there are a LOT of counterindications that would make me advise against recreational use, and until we have a lot of sound scientific research on it and a system set up to handle it therapeutically, recreational use is all we have.
I pay a lot of attention to the research that's been done on illegal drugs. I think it's really important. I hope nobody minds if I get long-winded about it.
