Draugnar, are you suggesting that cannabis or hallucinogens kill brain cells more than nicotine and alcohol? I assure you that this is not true. I'm not sure where you're getting this idea, but heavy drinking is significantly more damaging to the brain than any of the other four, and inhaling smoke in general can cause damage. There is no evidence that LSD nor magic mushrooms cause brain damage, and LSD is one of the most well documented and studied drugs out there. Cannabinoids have been found to have neurogenerative and neuroprotective properties as well, and I did see a paper that showed that moderate cannabis users had higher IQ's than non-users than heavy cannabis users.
rlumley, yes, that was one of my points. I consider the experience to be a valuable learning experience in general, and that was just one example of how this was so. I mostly made the point because I think a misconception exists that people who've tried hallucinogens think that they've seen the REAL reality, but I definitely recognize that the experience, while extremely vivid and convincing, is just the result of a chemical acting in my brain. But it shows the degree to which you can be convinced of a reality that simply is not true. Your point is valid, but doesn't change that hallucinogens are a valuable learning experience... how does your Objectivism answer Mary's room? Can you really understand what it is for something to be orange, if you've never experienced the colour orange? Even if you could piece together the puzzle from a wide and diverse set of sources, you could skip that and learn a whole lot more by simply being exposed to the colour orange. You're talking as though hallucinogens ought to be some sort of last resort for knowledge, as if it's a dangerous and damaging drug. This is simply not true. If taken responsibly, magic mushrooms and LSD are incredibly safe, and this is recognized by most every medical and scientific association, and has been shown through statistics, testing, and other research.