In a perfect world.
For all of the tokers/other drug users I know, there are very few I consider to have a respectable sense of judgement. Tack on a close friend that spent several months in rehab, and a very grungy backstory preceeding that, there's not much I can say in favor of drugs. If you feel the urge to disrespect your body for an unnatural high, go for it. But if a person is going to choose to not use, regardless of their reasoning or not, it's a position you shouldn't attack. Arguing anything along the lines of "don't knock it 'till you try it" isn't speaking from an enlightened or wiser position, it's just being a jackass.