Well, I am very intrigued where this thread has been and seems to be going - or at least my perception of that process thus far and looking forward. I would like to offer this as a more celear presentation of what I am thinking (and I leave this totally open to further debate):
In my view, this is a discussion/debate about (a) what is a drug, and (2) what is a gateway? and whose definition do we want to accept and adpot for the purposes of this discussion? There are many but in general, and paraphrasing, a drug is a substance that effects some change in physical/chemical/physiological functioning of a biological system. For these purposes, I will chose to adopt gateway as an avenue to a subsequent activity. In this case we are examining whether THC (marijuana) is a gateway to other drugs.
I think some very important points have been made by many. The elevation of nicotine C10H14N2 (as in cigarettes) as a drug is I believe appropriate. Nicotine is a naturally ocurring insecticide in the tobacco plant - i.e., it has an effect on the normal biological functioning of insects. Actually, so much that nicotine based insecticides have been banned for reasons of food safety.
I also think that alcohol is a drug. It has the ability to alter the function of a variety of biological systems, so the definition does seem to fit, from my perspective.
So in my case, I certainly had cigarettes and alcohol prior to my first puff of marijuana. Do I believe that my alcohol and cigarette experimentation led to my use of marijuana? I do not believe so. My experimentation with marijuana was pure curiousity - I had heard about the "evil drugs" when I was in Grade 8 (hash actually at the time) - and that their use would lead to a spiraling path of self destruction.
Did my use of marijuana lead to my use of other substances.....drugs. I suppose an argument can be made that it totally did from a pure sense of one followed the other, however the connotation of gateway, is that there was some "force" or some "influence" that marijuana had which "lead" you to other drugs. But I don't know what would happen if I would have been offered coke or heroin first? maybe in my mind I would have been less accepting of something harder if I had not already tried something softer, so to speak. like, marijuana, well that was ok...and didn't kill me, what's the other stuff like? and in the case of cigarettes and alcohol, the fact that I had that first, maybe that "allowed" me pyschologicaly to accept the "risk" of trying marijuana.
the other really important points that many people have brought forward include social circumstances (self esteen, family, etc), economic circumstances (availability and disposable cash), addictive personalities, and the likelihood that you will be drawn into the pleasure seeking behaviour.
I can certainly say that I KNOW I am a highliy addictive personality. I KNOW I could have MAJOR problems if I didn't exercise a high degree of self discipline. I KNOW my career and other ancillary aspects to my life are way TOO important to risk throwing it all away for blowing my brains wide open - because I need some "instant gratification". BUT....this is a totally constant struggle that I will ALWAYS have to deal with - every day, every week, every month, I have to be vigilent of the choices I make. Do I know why this is? Fuck I have been in counselling and other processes too often to describe or mention. My mom, my dad, got dropped on my head, my genetic makeup, my grandfather, the bully in Grade 7, fuck who cares - its reality - and if the desire for a drug free or moderated drug life is greater than to a highly impacted drug life - fucking deal with it - somehow. And as my dad always said - it totally ok to make mistakes - just don't make the same one too often - cuz we're human and we're supposed to be able to "learn" - and hopefully the one you do make, won't get you killed or put you in jail.
I guess what I'm trying to say, is that by experimenting with whatever, cigarettes, alcohol, and other lineages of drugs, you open your mind up to the opportunity, and to some degree the acceptance of other behaviours. Only you can judge yourself effectively - only you are responsible to yourself - only you need to be accountable to yourself - only you have to live with yourself. What other people think or say or do is their agenda - and although they may very well provide insight and experience that could prove useful to your individual circumstances - it all comes back to you. So if you want to smoke pot, and you choose to make the choice of elevating your drug use to something else - it is a choice that you make - and as with everything else in life - the choices you make all have consequences - some good, some not so good - some under your control - some not so much under your control - whatever the reality - life will soldier on, with or without you playing an active and participating role.