People willing to do one illegal drug may well be tempted to try another. If they're a weed smoker and hang out with weed smokers, odds are good at least one of their friends does more than just weed and may suggest other drugs to them.
However, would it not be accurate to say that said "subculture"...at least to the degree you're describing it...exists BECAUSE it's illegal.
IE to buy it you need to know someone who deals illegal substances. If they deal illegal substances, they likely deal other substances besides marijuana. If they deal other substances (and if those are more profitable) then there may be an attempt to sell you on trying something new. If you're already doing one thing illegal, the deterrent in doing another equally illegal thing becomes much smaller. If you're engaging in an illegal activity that is typically social, you're likely doing it with other people open to engaging in illegal activity. If you're around people open to engaging in illegal activity, you have a higher chance of running into OTHER forms of similar illegal activity and persuaded to join in. etc.
All of this is kind of book ended off the fact that Marijuana is legal. It's the same reason someone may argue that UNDERAGE smoking or UNDERAGE drinking may be a gateway to other things, but you generally wouldn't say it about people of a legal age that smoke or drink.
If anything, I think the "gateway" argument is actually a strong one for
LEGALIZING, not keeping it illegal. The "gateway" isn't like it magically makes your brain go "NOW GIVE ME CRACK!". The "gateway" is that it reduces the legal deterrent to go onto other drugs, while putting you deeper into contact with an environment and culture that facilitates going further.
If you could go into the local ABC store and buy a 10 pack of joints, and are able to smoke it socially amongst friends who are generally upstanding with the law, then it significantly reduces the amount of contact and thus opportunity that's provided through the old methods of acquisition and group use.
I'd say it's not so much that mj is a gateway in an of itself, but that it tends to expose users to others who do harder drugs, and to the contacts needed to acquire same... and that the inclination to use one illegal drug makes it more likely you might give in to the temptation to try something else when offered or suggested.
Not an inherent property of mj itself, in other words, but a risk associated with the subculture that uses it.
From personal experience: some people smoke weed all their life and never do anything harder.... but a good many do try other stuff.[/QUOTE]